Android and Java

Audio Recording in Android

2013-03-21T05:13:00.002-07:00

Simple State Diagram for Media Recorder...

Here Sequence of Method call is as per state diagram of media Recorder .... Otherwise Invalid sate call Error will be Occur........
Steps:
1) Also her two permission add in Android manifest file

<uses-permission android:name="android.permission.RECORD_AUDIO" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

2) This is java file coding
audiorecording.java

package com.example.recording;

import java.io.File;
import java.io.FileDescriptor;

import android.media.MediaRecorder;
import android.os.Bundle;
import android.os.Environment;
import android.provider.MediaStore;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.support.v4.app.NavUtils;
/*
* O@K Tech....
*/
public class audiorecording extends Activity implements OnClickListener {
Button start,stop,frmt;

private MediaRecorder rcorder = null;
private int opfrmt[] = {MediaRecorder.OutputFormat.MPEG_4,MediaRecorder.OutputFormat.THREE_GPP};
private int curfrmt = 0;
private String filextsn[] = {".mp4",".3gp"};
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recording);
start = (Button)findViewById(R.id.button1);
stop = (Button)findViewById(R.id.button2);
frmt = (Button)findViewById(R.id.button3);
start.setOnClickListener(this);
stop.setOnClickListener(this);
frmt.setOnClickListener(this);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_recording, menu);
return true;
}

@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.button1:
System.out.println("Recoding start");
startrecording();
break;
case R.id.button2:
System.out.println("Recoding stop");
stoprecording();
break;
case R.id.button3:
System.out.println("format check");
showDialog(1);

break;

default:
break;
}

}

private void stoprecording() {
System.out.println("stop recoding method");
if(rcorder != null)
{
rcorder.stop();
rcorder.reset();
rcorder.release();

rcorder = null;

}

}

private void startrecording() {
System.out.println("startrecoding method");
rcorder = new MediaRecorder();

rcorder.setAudioSource(MediaRecorder.AudioSource.MIC);

rcorder.setOutputFormat(opfrmt[curfrmt]);
rcorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
rcorder.setOutputFile(getfilepath());

try {
rcorder.prepare();
rcorder.start();
} catch (Exception e) {

}
}

private String getfilepath() {
System.out.println("getfile path method");
String filepath = Environment.getExternalStorageDirectory().getAbsolutePath();
File file = new File(filepath, "recodingfile");

if(!file.exists())
file.mkdir();

return(file.getAbsolutePath() + "/" + System.currentTimeMillis() + filextsn[curfrmt]);
}
@Override
protected Dialog onCreateDialog(int id) {
System.out.println("oncreate dialog");
AlertDialog.Builder albuilddlg = new AlertDialog.Builder(this);
String frmt[] = {"mp4","3gp"};
albuilddlg.setTitle("Select Format.....");
albuilddlg.setSingleChoiceItems(frmt, curfrmt, new DialogInterface.OnClickListener() {

@Override
public void onClick(DialogInterface dialog, int which) {
curfrmt = which;

}
});

return albuilddlg.create();
}

}

3).Xml file

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:text="Start" />

<Button
android:id="@+id/button2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toRightOf="@+id/button1"
android:text="Stop" />

<Button
android:id="@+id/button3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_toRightOf="@+id/button2"
android:text="Change Format" />

<ImageView
android:id="@+id/imageView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="@+id/button2"
android:layout_centerHorizontal="true"
android:layout_marginBottom="138dp"
android:src="@drawable/audio" />

</RelativeLayout>

Download This Project click here....

out put of this porgram

All iz well

OAK Tech.......

How To Make Jar file From .java File

2013-01-08T02:57:00.001-08:00

Follow the Below Steps for Make .jar file from Java

Creating a jar File in Command Prompt

Start Command Prompt.
Navigate to the folder that holds your class files:
C:\>cd \mywork
Compile your class(es):
C:\mywork> javac *.java
Create a manifest file:
C:\mywork> echo Main-Class: DanceStudio >manifest.txt
Create a jar file:
C:\mywork> jar cvfm DanceStudio.jar manifest.txt *.class
Test your jar:
C:\mywork> DanceStudio.jar

Calculator in Java

2013-01-05T21:14:00.000-08:00

This is One simple calculator using java swing so.. enjoy it....

her all buttons and textbox are put in panel so every row in calculator its separate on panel.
This calculator made by me during 7th semester.

Realy java is my favourite Language . so

Steps for run Below code:-

1) Copy below code in notepade
2) Save this file as cal.java
3) open cmd and goto path of cal.java
4) Now Firts compile it using below command
javac cal.java
5) and run it using following cammand
java cal.java

Code:
File : cal.java

import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.applet.*;

/*
<applet code="cal" width=250 height=300>
</applet>
*/

class calc extends JFrame implements ActionListener
{
FlowLayout fl;
GridLayout gr;
JPanel p1,p2,p3,p4,p5,p6,p7,p8,p9;
JButton b[],plus,eql,minus,mul,div,ce;
JTextField t1;
int a,c,r=0;
String s="";
public calc()
{
gr = new GridLayout(8,1);
setLayout(gr);
fl = new FlowLayout(0);
p1 = new JPanel();
p1.setLayout(fl);
t1 = new JTextField(15);
p1.add(t1);
add(p1);
b = new JButton[10];
for(int i=0;i<10;i++)
{
b[i] = new JButton( String.valueOf(i) );
}
p3 = new JPanel();
p3.setLayout(fl);
plus = new JButton("+");
plus.addActionListener(this);
p3.add(plus);
ce = new JButton(" CE ");
ce.addActionListener(this);
p3.add(ce);
add(p3);
p4 = new JPanel();
p4.setLayout(fl);
mul = new JButton("* ");
mul.addActionListener(this);
p4.add(mul);
div = new JButton("/ ");
div.addActionListener(this);
p4.add(div);
minus = new JButton(" -");
minus.addActionListener(this);
p4.add(minus);
add(p4);
p5 = new JPanel();
p5.setLayout(fl);
p5.add( b[7] );
b[7].addActionListener(this);
p5.add( b[8] );
b[8].addActionListener(this);
p5.add( b[9] );
b[9].addActionListener(this);
add(p5);
p6 = new JPanel();
p6.setLayout(fl);
p6.add(b[4]);
b[4].addActionListener(this);
p6.add(b[5]);
b[5].addActionListener(this);
p6.add(b[6]);
b[6].addActionListener(this);
add(p6);
p7 = new JPanel();
p7.setLayout(fl);
p7.add(b[1]);
b[1].addActionListener(this);
p7.add(b[2]);
b[2].addActionListener(this);
p7.add(b[3]);
b[3].addActionListener(this);
add(p7);
p8 = new JPanel();
p8.setLayout(fl);
p8.add(b[0]);
b[0].addActionListener(this);
eql = new JButton(" = ");
eql.addActionListener(this);
p8.add(eql);
add(p8);
setTitle("O@K Tech. RVS");
setLocation(100,100);
setSize(200,300);
setVisible(true);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public void actionPerformed(ActionEvent e)
{
for(int i=0; i<b.length; i++)
{
if(e.getSource() == b[i])
{
switch(i)
{
case 0:
s=s+"0";
break;
case 1:
s=s+"1";
break;
case 2:
s=s+"2";
break;
case 3:
s=s+"3";
break;
case 4:
s=s+"4";
break;
case 5:
s=s+"5";
break;
case 6:
s=s+"6";
break;
case 7:
s=s+"7";
break;
case 8:
s=s+"8";
break;
case 9:
s="9";
break;
}
t1.setText(s);
}
}
if(e.getSource() == plus)
{
a=Integer.parseInt(s);
s="";
t1.setText("");
r=1;
}
else if(e.getSource() == minus)
{
a=Integer.parseInt(s);
s="";
t1.setText("");
r=2;
}
else if(e.getSource() == mul)
{
a=Integer.parseInt(s);
s="";
t1.setText("");
r=3;
}
else if(e.getSource() == div)
{
a=Integer.parseInt(s);
s="";
t1.setText("");
r=4;
}
else if(e.getSource() == ce)
{
s="";
t1.setText("");
}
else if(e.getSource() == eql)
{
switch(r)
{
case 1:
c = a + Integer.parseInt(t1.getText());
break;
case 2:
c = a - Integer.parseInt(t1.getText());
break;
case 3:
c = a * Integer.parseInt(t1.getText());
break;
case 4:
c = a / Integer.parseInt(t1.getText());
break;
}
t1.setText(""+c);
}
}
}
public class cal
{
public static void main(String args[])
{
calc cl = new calc();
}
}

Output of Program:

Download .jar file

Text To Speech Application in Android

2012-09-14T02:53:00.000-07:00

This Application Convert Text into Speech.... Enjoy it.....

Download Code (Click Here....)

Download .apk File For Android(2.2 upto) Mobile (Click Here...)

Show in Bellow Code For TextToSpeech.java

here use TextToSpeech Class for Access the functionality of conversion of text to speech...

setLanguage(Locale.ENGLISH);

method is use for set language like us , uk etc.

Also Call shutdown() method in onDestroy() for release All TextToSpeech Objects.

Show in Bellow .java code

1) First Create One XML file in which one TextView ,one EditText and one Button Show in Bellow Code

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >

<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="88dp"
android:text="Text To Speech"
tools:context=".TextToSpeech" />

<EditText
android:id="@+id/editText1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView1"
android:layout_centerHorizontal="true"
android:layout_marginTop="47dp"
android:ems="10" />

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/editText1"
android:layout_centerHorizontal="true"
android:layout_marginTop="62dp"
android:text="TextToSpeech Button" />

</RelativeLayout>

2) TextToSpeech.java

package com.example.texttospeech;

import java.util.Locale;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.speech.tts.TextToSpeech.OnInitListener;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
// O@K Tech.
public class TextToSpeech extends Activity {
EditText mSpeechText;
Button mSubmit;
android.speech.tts.TextToSpeech ttos;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_text_to_speech);
mSpeechText = (EditText)findViewById(R.id.editText1);
mSubmit = (Button)findViewById(R.id.button1);
mSubmit.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
speakEditText();
}
});
ttos = new android.speech.tts.TextToSpeech(this,new OnInitListener() {

@Override
public void onInit(int status) {
if(status == android.speech.tts.TextToSpeech.SUCCESS){
int langSet = ttos.setLanguage(Locale.ENGLISH);
if(langSet == android.speech.tts.TextToSpeech.LANG_NOT_SUPPORTED || langSet == android.speech.tts.TextToSpeech.LANG_MISSING_DATA){
Log.e("TextToSpeech", "Language is Not Support.");
// Below Three Line is Optional so Comment it.
Intent inSp = new Intent();
inSp.setAction(android.speech.tts.TextToSpeech.Engine.ACTION_INSTALL_TTS_DATA);
startActivity(inSp);
}
else{
mSubmit.setEnabled(true);
speakEditText();
}
}
else{
Log.e("TextToSpeech", "TextToSpeech is not Init....");
}
}
});
}
protected void speakEditText() {
String txt = mSpeechText.getText().toString();
ttos.speak(txt, android.speech.tts.TextToSpeech.QUEUE_FLUSH, null);
Toast.makeText(this, "Call SpeakEdit Method", Toast.LENGTH_LONG).show();

}
@Override
protected void onDestroy() {
if(ttos != null){
ttos.stop();
ttos.shutdown();
}
super.onDestroy();
}
}

3) OutPut Show in Bellow image..................

All iZ Well

Animation Demo in Android(Tween Animation)

2012-09-12T05:59:00.001-07:00

This Animation Demo.....

Download This Code Click Here......

The view animation framework supports both tween and frame by frame animations, which can both be declared in XML. The following sections describe how to use both methods.

Tween animation

An animation defined in XML that performs transitions such as rotating, fading, moving, and stretching on a graphic.

file location:

res/anim/filename.xml The filename will be used as the resource ID.

compiled resource datatype:

Resource pointer to an Animation.

resource reference:

In Java: R.anim.filename In XML: @[package:]anim/filename

syntax:

<?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:interpolator="@[package:]anim/interpolator_resource"
    android:shareInterpolator=["true" | "false"] >
    <alpha
        android:fromAlpha="float"
        android:toAlpha="float" />
    <scale
        android:fromXScale="float"
        android:toXScale="float"
        android:fromYScale="float"
        android:toYScale="float"
        android:pivotX="float"
        android:pivotY="float" />
    <translate
        android:fromXDelta="float"
        android:toXDelta="float"
        android:fromYDelta="float"
        android:toYDelta="float" />
    <rotate
        android:fromDegrees="float"
        android:toDegrees="float"
        android:pivotX="float"
        android:pivotY="float" />
    <set>
        ...
    </set>
</set>

The file must have a single root element: either an <alpha>, <scale>, <translate>, <rotate>, or <set>element that holds a group (or groups) of other animation elements (even nested <set> elements).

elements:

<set>

A container that holds other animation elements (<alpha>, <scale>, <translate>, <rotate>) or other <set> elements. Represents an AnimationSet.

attributes:

android:interpolator: Interpolator resource. An Interpolator to apply on the animation. The value must be a reference to a resource that specifies an interpolator (not an interpolator class name). There are default interpolator resources available from the platform or you can create your own interpolator resource. See the discussion below for more about Interpolators.
android:shareInterpolator: Boolean. "true" if you want to share the same interpolator among all child elements.

<alpha>

A fade-in or fade-out animation. Represents an AlphaAnimation.

attributes:

android:fromAlpha: Float. Starting opacity offset, where 0.0 is transparent and 1.0 is opaque.
android:toAlpha: Float. Ending opacity offset, where 0.0 is transparent and 1.0 is opaque.

For more attributes supported by <alpha>, see the Animation class reference (of which, all XML attributes are inherrited by this element).

<scale>

A resizing animation. You can specify the center point of the image from which it grows outward (or inward) by specifying pivotX and pivotY. For example, if these values are 0, 0 (top-left corner), all growth will be down and to the right. Represents a ScaleAnimation.

attributes:

android:fromXScale: Float. Starting X size offset, where 1.0 is no change.
android:toXScale: Float. Ending X size offset, where 1.0 is no change.
android:fromYScale: Float. Starting Y size offset, where 1.0 is no change.
android:toYScale: Float. Ending Y size offset, where 1.0 is no change.
android:pivotX: Float. The X coordinate to remain fixed when the object is scaled.
android:pivotY: Float. The Y coordinate to remain fixed when the object is scaled.

For more attributes supported by <scale>, see the Animation class reference (of which, all XML attributes are inherrited by this element).

<translate>

A vertical and/or horizontal motion. Supports the following attributes in any of the following three formats: values from -100 to 100 ending with "%", indicating a percentage relative to itself; values from -100 to 100 ending in "%p", indicating a percentage relative to its parent; a float value with no suffix, indicating an absolute value. Represents a TranslateAnimation.

attributes:

android:fromXDelta: Float or percentage. Starting X offset. Expressed either: in pixels relative to the normal position (such as "5"), in percentage relative to the element width (such as "5%"), or in percentage relative to the parent width (such as "5%p").
android:toXDelta: Float or percentage. Ending X offset. Expressed either: in pixels relative to the normal position (such as "5"), in percentage relative to the element width (such as "5%"), or in percentage relative to the parent width (such as "5%p").
android:fromYDelta: Float or percentage. Starting Y offset. Expressed either: in pixels relative to the normal position (such as "5"), in percentage relative to the element height (such as "5%"), or in percentage relative to the parent height (such as "5%p").
android:toYDelta: Float or percentage. Ending Y offset. Expressed either: in pixels relative to the normal position (such as "5"), in percentage relative to the element height (such as "5%"), or in percentage relative to the parent height (such as "5%p").

For more attributes supported by <translate>, see the Animation class reference (of which, all XML attributes are inherrited by this element).

<rotate>

A rotation animation. Represents a RotateAnimation.

attributes:

android:fromDegrees: Float. Starting angular position, in degrees.
android:toDegrees: Float. Ending angular position, in degrees.
android:pivotX: Float or percentage. The X coordinate of the center of rotation. Expressed either: in pixels relative to the object's left edge (such as "5"), in percentage relative to the object's left edge (such as"5%"), or in percentage relative to the parent container's left edge (such as "5%p").
android:pivotY: Float or percentage. The Y coordinate of the center of rotation. Expressed either: in pixels relative to the object's top edge (such as "5"), in percentage relative to the object's top edge (such as"5%"), or in percentage relative to the parent container's top edge (such as "5%p").

For more attributes supported by <rotate>, see the Animation class reference (of which, all XML attributes are inherrited by this element).

example:

XML file saved at res/anim/property.xml:

 <?xml version="1.0" encoding="utf-8"?>
<set xmlns:android="http://schemas.android.com/apk/res/android"
    android:shareInterpolator="false">
    <scale
        android:interpolator="@android:anim/accelerate_decelerate_interpolator"
        android:fromXScale="1.0"
        android:toXScale="1.4"
        android:fromYScale="1.0"
        android:toYScale="0.6"
        android:pivotX="50%"
        android:pivotY="50%"
        android:fillAfter="false"
        android:duration="700" />
    <set
        android:interpolator="@android:anim/accelerate_interpolator"
        android:startOffset="700">
        <scale
            android:fromXScale="5.6"
            android:toXScale="2"
            android:fromYScale="5.0"
            android:toYScale="0.0"
            android:pivotX="25%"
            android:pivotY="50%"
            android:duration="500" />
        <rotate
            android:fromDegrees="0"
            android:toDegrees="-90"
            android:toYScale="0.0"
            android:pivotX="50%"
            android:pivotY="50%"
            android:duration="700" />
    </set>
</set>

This application code will apply the animation to an ImageView and start the animation:

import android.os.Bundle;
import android.animation.AnimatorInflater;
import android.animation.AnimatorSet;
import android.app.Activity;
import android.view.Menu;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.TextView;
//O@K Tech..
public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.animator);
        ImageView img = (ImageView)findViewById(R.id.imageView1);
        Animation amnt = AnimationUtils.loadAnimation(this,R.anim.property);
        img.startAnimation(amnt);
       
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}

Android Tab Layout Application

2012-09-11T04:55:00.004-07:00

Hello This Android Tab Layout Application.............. Enjoy it..............

Download This Code Click here

1) In this post we need three separate activities for three tab screens. So let’s get started by creating a simple project by opening eclipse IDE. Create a new project File -> New -> Android Project and give activity name as MainActivity.

2) Now open your activity_main.xml under res -> layout folder and type the following code.

<?xml version="1.0" encoding="utf-8"?>

<TabHost

xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@android:id/tabhost"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_alignParentLeft="true"

android:layout_alignParentTop="true" >

<LinearLayout

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical" >

<TabWidget

android:id="@android:id/tabs"

android:layout_width="match_parent"

android:layout_height="wrap_content" >

</TabWidget>

<FrameLayout

android:id="@android:id/tabcontent"

android:layout_width="match_parent"

android:layout_height="match_parent" >

</FrameLayout>

</LinearLayout>

</TabHost>

3) Now we need 3 activities and 3 xml layouts for three tabs. So create three activities by right click on your package folder and create classes and name them asMusic.java,Photo.javaand video.java. Type the following code respectively.

Right Click on package folder -> New -> Class

Music.java

import android.app.Activity;

import android.os.Bundle;

//O@K Tech

public class Music extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

setContentView(R.layout.music_layout);

}

Photo.java

import android.app.Activity;

import android.os.Bundle;

//O@K Tech

public class Photo extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

setContentView(R.layout.photo_layout);

}

video.java

import android.app.Activity;

import android.os.Bundle;

public class video extends Activity{

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

setContentView(R.layout.video);

}

4) Now create 3 xml layouts by right clicking on res/layout -> New -> Android XML File and name them as photo_layout.xml, music_layout.xml and video.xml and type the following code in respective files.

music_layout.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

<TextView

android:id="@+id/textView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Play Music.... "

android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout>

photo_layout.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

<TextView

android:id="@+id/textView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Hello Photo view"

android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout>

video.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

<TextView

android:id="@+id/textView1"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="Video................"

android:textAppearance="?android:attr/textAppearanceLarge" />

</LinearLayout>

5) Now open MainActivity.java and type the following code. In the following code we are creating three TabSepcs and adding them to TabHost.

MainActivity.java

package com.example.tagdemo;

import android.os.Bundle;

import android.app.Activity;

import android.app.TabActivity;

import android.content.Intent;

import android.view.Menu;

import android.widget.TabHost;

import android.widget.TabHost.TabSpec;

// O@K Tech......

public class MainActivity extends TabActivity {

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

System.out.println("helloo");

@SuppressWarnings("deprecation")

TabHost tbh = getTabHost();

TabSpec tabspecmusic = tbh.newTabSpec("Music");

tabspecmusic.setIndicator("Music",getResources().getDrawable(R.drawable.ic_launcher));

Intent imusic = new Intent(this, Music.class);

tabspecmusic.setContent(imusic);

TabSpec tabspecphoto = tbh.newTabSpec("Photo");

tabspecphoto.setIndicator("Photo",getResources().getDrawable(R.drawable.ic_action_search));

Intent iphoto = new Intent(this,Photo.class);

tabspecphoto.setContent(iphoto);

TabSpec tabspecv = tbh.newTabSpec("video");

tabspecv.setIndicator("video",getResources().getDrawable(R.drawable.ic_action_search));

Intent iv = new Intent(this,video.class);

tabspecv.setContent(iv);

tbh.addTab(tabspecmusic);

tbh.addTab(tabspecphoto);

tbh.addTab(tabspecv);

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.activity_main, menu);

return true;

}

6) Now everything is ready and before running your project make sure that you an entry of new activity name in AndroidManifest.xml file. Open you AndroidManifest.xml file and modify the code as below

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="com.example.tagdemo"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk

android:minSdkVersion="8"

android:targetSdkVersion="15" />

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name"

android:theme="@style/AppTheme" >

<activity

android:name=".MainActivity"

android:label="@string/title_activity_main" >

<intent-filter>

</intent-filter>

</activity>

<activity

android:name=".Music"

android:label="@string/title_activity_main" >

<intent-filter>

</intent-filter>

</activity>

<activity

android:name=".Photo"

android:label="@string/title_activity_main" >

<intent-filter>

</intent-filter>

</activity>

<activity

android:name=".video"

android:label="@string/title_activity_main" >

<intent-filter>

</intent-filter>

</activity>

</application>

</manifest>

Output of Above code in Emulator :-

Login Application using Database with dialog demo

2012-09-06T05:49:00.000-07:00

Follow Below Steps for make simple login applicaiton in Android using database with Dialog demo.

1)DataBaseDemoActivity.java

This file diplay login page and trasfer two edit text data into second activity........

package database.co.in;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class DataBaseDemoActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
EditText mtxt_email, mtxt_password;
Button mLogin;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mtxt_email = (EditText)findViewById(R.id.editEmail_id);
mtxt_password = (EditText)findViewById(R.id.editPassword);
mLogin = (Button)findViewById(R.id.button1);
mLogin.setOnClickListener(this);

}
@Override
public void onClick(View v) {
String email = mtxt_email.getText().toString();
String password = mtxt_password.getText().toString();
System.out.println("Email id:-"+email);
System.out.println("Password:-"+password);

Intent dbintent = new Intent(this.getApplicationContext(),DbEntry.class);
dbintent.putExtra("p_email", email);
dbintent.putExtra("p_password", password);

startActivity(dbintent);

}
}

2)main.xml

This is login page gui.. also this file need one header.xml which include externally.......

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
android:background="@drawable/apple1" >

<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<TextView
android:id="@+id/textEmail_id"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="69dp"
android:text="Email ID"
android:textSize="20dp"
android:gravity="center|left"
android:textColor="@android:color/holo_purple" />

<EditText
android:id="@+id/editEmail_id"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:layout_alignLeft="@+id/button1"
android:layout_alignRight="@+id/button1"
android:layout_below="@+id/textEmail_id"
android:layout_marginTop="10dp" />

<TextView
android:id="@+id/textPassword"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textEmail_id"
android:layout_below="@+id/editEmail_id"
android:text="Password"
android:textSize="20dp"
android:textColor="@android:color/holo_purple" />

<EditText
android:id="@+id/editPassword"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:layout_alignLeft="@+id/editEmail_id"
android:layout_alignRight="@+id/button1"
android:layout_below="@+id/textPassword"
android:layout_marginTop="10dp" >

<requestFocus />
</EditText>

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/editPassword"
android:layout_centerHorizontal="true"
android:layout_marginTop="24dp"
android:background="@drawable/login" />

<include layout="@layout/header"/>
</RelativeLayout>

</LinearLayout>
3) header.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
>

<TextView
android:id="@+id/textView2"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_marginLeft="35dp"
android:text="Welcome To @pple"
android:textSize="25dp"
android:textColor="@android:color/holo_purple" />

</LinearLayout>

4) DbEntry.java

Below code for database logic..... and show Dialog in second page check. it

package database.co.in;

import android.app.Activity;
import android.app.Dialog;
import android.content.Context;
import android.content.Intent;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;
import android.os.Bundle;
import android.widget.Toast;

public class DbEntry extends Activity {
SQLiteDatabase db;

@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
System.out.println("All iz well. ");
Intent getdbintent = getIntent();
String email = getdbintent.getStringExtra("p_email");
String password = getdbintent.getStringExtra("p_password");
db = openOrCreateDatabase("login.db",SQLiteDatabase.CREATE_IF_NECESSARY ,null);
String createTable = "CREATE TABLE IF NOT EXISTS info ("
+ "Emailid TEXT,"
+ "PassWord TEXT);";
db.execSQL(createTable);
String insertData = "INSERT or replace INTO info (Emailid, PassWord) VALUES('"+email+"','"+password+"')" ;
db.execSQL(insertData);
db.close();
System.out.println("All iz well.database has benn insert successfully. ");
Toast.makeText(getApplicationContext(), "welcome to o@k Tech"+email+"Password+"+password, Toast.LENGTH_LONG).show();
showDialog(1);
}
protected Dialog onCreateDialog(int i) {
Dialog dialog = null;
switch (i) {
case 1:
dialog = new Dialog(this);
dialog.setTitle("Welcome to O@k Tech...... ....");
dialog.setContentView(R.layout.dialog);
break;

default:
break;
}

return dialog;

}

}
5) dialog.xml

This file content only one button which is display on dialog box .

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Thanx to Login........." />

</LinearLayout>

6) AndroidManiFest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="database.co.in"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15" />

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name" >

<activity

android:label="@string/app_name"

android:name=".DataBaseDemoActivity" >

<intent-filter >

</intent-filter>

</activity>

<activity

android:label="@string/app_name"

android:name=".DbEntry" >

<intent-filter >

</intent-filter>

</activity>

</application>

</manifest>

Output and Require Backgroud images for this project.......:

Application Output:-

Camara Application in Android(Use Hardware Camara)

2012-08-27T06:29:00.001-07:00

hi ....
write Following code in your project

first create camaratest android project.......
this example for take image and view in below image view check it........ and enjoy

1) CamaratestActivity.java

package com.in.test;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.hardware.Camera.ShutterCallback;
import android.os.Bundle;
import android.os.Handler;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
/*
* O@K tech...
*/
public class CamaratestActivity extends Activity implements SurfaceHolder.Callback ,OnClickListener {
Camera camera;
SurfaceView surfaceview;
SurfaceHolder mHolder ;
Button btnSnap;
ImageView mPic;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
surfaceview = (SurfaceView)findViewById(R.id.surfaceView1);// view camera view in main xml.... check it
mHolder = surfaceview.getHolder();
mHolder.addCallback(this);
btnSnap = (Button)findViewById(R.id.button1);
btnSnap.setOnClickListener(this);
mPic = (ImageView)findViewById(R.id.imageView1);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
System.out.println("surfacechanged is called");

try{
camera.setPreviewDisplay(mHolder);
Camera.Parameters parameter = camera.getParameters();
camera.setParameters(parameter);
camera.startPreview();

}
catch (Exception e) {
// TODO: handle exception
}

}
@Override
public void surfaceCreated(SurfaceHolder holder) {
System.out.println("surfacreate is called");
try{

camera = Camera.open();

}
catch (Exception e) {
System.out.println("Error:"+e);
}

}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
System.out.println("surfacedestroy is called");
camera.stopPreview();
camera.release();
camera = null;

}
@Override
public void onClick(View v) {

camera.takePicture(shutter, raw, postview, jpeg);// this class for take pic .
Handler handler=new Handler();
handler.postDelayed(new Runnable() {

@Override
public void run() {
// TODO Auto-generated method stub
camera.startPreview();
}
}, 1000);

//camera.startPreview();
}
ShutterCallback shutter = new ShutterCallback() {

@Override
public void onShutter() {
System.out.println("Shuttercallback picature call back.....");

}
} ;
PictureCallback raw = new PictureCallback() {

@Override
public void onPictureTaken(byte[] data, Camera camera) {
System.out.println("raw .. picature call back.....");

}
};
PictureCallback jpeg = new PictureCallback() {

@Override
public void onPictureTaken(byte[] data, Camera camera) {
System.out.println("jpeg picature call back.....");
Bitmap btmCamerapic = BitmapFactory.decodeByteArray(data,0,data.length);
mPic.setImageBitmap(btmCamerapic);

}
};
PictureCallback postview = new PictureCallback() {

@Override
public void onPictureTaken(byte[] data, Camera camera) {
System.out.println("postview... picature call back.....");

}
};

}

2)main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Snap Card..." />
<FrameLayout android:layout_width="fill_parent"
android:layout_height="250dp">
<RelativeLayout android:layout_width="fill_parent"
android:layout_height="fill_parent">
<SurfaceView
android:id="@+id/surfaceView1"
android:layout_width="fill_parent"
android:layout_height="250dp" />

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="bottom"
android:text="Snap" />
</RelativeLayout>
</FrameLayout>

<ImageView
android:id="@+id/imageView1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>

</LinearLayout>

3) AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.in.test"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />

<application
android:icon="@drawable/camera"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".CamaratestActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

All iz well
Output

Media Player Programming in Android

2012-08-24T05:42:00.000-07:00

Hi Friends.

This is Small Media Player (Start and Stop) Application

1) First Create Android Project.(mediap)

2) Create raw Folder in res Folder

now copy paste one .mp3 file in raw folder show in above image res/raw/a.mp3
3) Now Edit main.xml see in Bellow

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal">

<Button
android:id="@+id/Start"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Start" />

<Button
android:id="@+id/Stop"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Stop" />

</LinearLayout>
4) Now Create Following Activity

package media.p.in;

import android.app.Activity;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
/*
* O@K Tech : Sukhadiya Raviraj
*/
public class MediapActivity extends Activity implements OnClickListener {

MediaPlayer mPlayer;// Media Player Object
Button start,stop;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mPlayer = MediaPlayer.create(this, R.raw.a);
start = (Button)findViewById(R.id.Start);
stop = (Button)findViewById(R.id.Stop);
start.setOnClickListener(this);
stop.setOnClickListener(this);
}

public void onClick(View v) {
if(start.isPressed())
{
mPlayer.start();// this method for Start Song
}
else if(stop.isPressed())
{
mPlayer.stop();//this method for Stop Song
mPlayer.reset();
}
}
}

Here MediaPlayer Object create and give the path of .mp3 file in create() method and use stop() and start() method for start and stop music .

5) AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="media.p.in"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15" />

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".MediapActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

6) Now Run in Emulator . and see below Out put

Click on Start and Stop Button for Start and Stop Music.......

All iz Well

How to add a menu in a programmatic manner in Android

2012-08-21T05:25:00.002-07:00

Hello Friends.

Follow Below Step for Create Programmatic Menu in Android.
Here Use onCreateOptionsMenu(Menu menu) Override method.

1) First Create Simple Android Project (menudemo)

2) Now edit string.xml(Path:- res/values/string.xml)

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello">Hello World, MenudemoActivity!</string>
<string name="app_name">Menudemo</string>
<string name="HomeOption">Home</string>
<string name="Oak">a@k</string>
</resources>

Here above Code for Manualy create String Home and a@k.

3) Edit MenudemoActivity.java (this is Android Activity)

import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;

public class MenudemoActivity extends Activity {
/** Called when the activity is first created. */
int id_menu = 1;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// TODO Auto-generated method stub
menu.add(R.string.HomeOption);
menu.add(R.string.Oak);
menu.add("Welcome");
return super.onCreateOptionsMenu(menu);
}
}

Here in Above Code onCreateOptionsMenu(Menu menu) override method use for create menu. then use add method for add string from string.xml or manualy like "welcome"
4) Now Run Android Application.

See in Emulator after Run project Click on Menu Button and See Below Output.

Create Simple Widget in Android

2012-08-20T05:56:00.000-07:00

Hi .
Here we Discuss about how to create Simple Widget in android...
Here use AppWidgetProvider class .

First Create Simple android project name is widget.

1) res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:orientation="vertical"
android:layout_gravity="center"
android:background="@android:color/holo_orange_light"
android:layout_height="wrap_content">

<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="welcome" />

<TextView android:id="@+id/widget_textview"
android:layout_height="wrap_content"
android:layout_width="wrap_content"
android:layout_gravity="center_horizontal|center"
android:layout_marginTop="5dip"
android:padding="10dip"
android:text="Welcome Oak Tech."
android:textColor="@android:color/black"/>
</LinearLayout>

2) AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="widget.co.in"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15" />

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >

<receiver android:name=".WidgetActivity" android:label="@string/app_name">
<intent-filter>
<action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
</intent-filter>
<meta-data android:name="android.appwidget.provider"
android:resource="@xml/welcome" />
</receiver>
</application>

</manifest>

3) create xml folder in res . res/xml/welcome.xml

this .xml file create appwidget-provider tag for view widget.

<?xml version="1.0" encoding="utf-8"?>
<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
android:minWidth="146dip"
android:minHeight="72dip"
android:updatePeriodMillis="10000"
android:initialLayout="@layout/main"
/>

4) Create Following Activity.
WidgetActivity.java

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

import android.app.Activity;
import android.appwidget.AppWidgetManager;
import android.appwidget.AppWidgetProvider;
import android.content.ComponentName;
import android.content.Context;
import android.os.Bundle;
import android.text.format.DateFormat;
import android.widget.RemoteViews;

public class WidgetActivity extends AppWidgetProvider {
}

5) Run Above Application and see in console

Uploading widget.apk onto device 'emulator-5554'

Installing widget.apk...
Success!
/widget/bin/widget.apk installed on device
Done!

6) Now Goto Emulator and Open widget (long press left click on home screen) . and See Widget window and longpress on widget icon for our application.
see Button and Textview in widget window.

output:

WebApp in Android

2012-08-20T05:34:00.000-07:00

First Create Simple Android Project(webapp).
We need WebView in xml for Develop WebApp in Android . So Following Step are Create simple WebApp in android.
1) res/layout/main.xml
paste following code in main.xml

<?xml version="1.0" encoding="utf-8"?>
<WebView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>

2)webapp.java
following Activity is open google.com page in webview.

import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;

import org.apache.cordova.*;

public class webapp extends Activity {

@Override
public void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
WebView wb = (WebView)findViewById(R.id.webview);
wb.loadUrl("http://www.google.com");

}

}

3) Run the Above Application and output is.

Android HelloWorld Example

2012-08-20T05:22:00.000-07:00

After install android Create New Android Helloworld Application.
1) HelloWorld.java
package co.in.helloworld;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class HelloWorld extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
System.out.println("Hello World......");

}
}

2) res/layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello" /> (We can write own text in between " ")

</LinearLayout>

3) res/values/string.xml(Optional step)

<?xml version="1.0" encoding="utf-8"?>
<resources>

<string name="hello">Hello World, HelloWorldActivity!</string>
<string name="app_name">HelloWorld</string>

</resources>

4) AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="co.in.helloworld"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="15" />

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".HelloWorldActivity" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>

</manifest>

5) Run Android Application and Got Output in Emulator.

Android Activity

2012-08-06T04:00:00.000-07:00

An activity is a single, focused thing that the user can do. Almost all activities interact with the user, so the Activity class takes care of creating a window for you in which you can place your UI with setContentView(View). While activities are often presented to the user as full-screen windows, they can also be used in other ways: as floating windows (via a theme with windowIsFloating set) or embedded inside of another activity (using ActivityGroup). There are two methods almost all subclasses of Activity will implement:

onCreate(Bundle) is where you initialize your activity. Most importantly, here you will usually call setContentView(int) with a layout resource defining your UI, and using findViewById(int) to retrieve the widgets in that UI that you need to interact with programmatically.
onPause() is where you deal with the user leaving your activity. Most importantly, any changes made by the user should at this point be committed (usually to the ContentProvider holding the data).

To be of use with Context.startActivity(), all activity classes must have a corresponding <activity> declaration in their package's AndroidManifest.xml.

Topics covered here:

Developer Guides

The Activity class is an important part of an application's overall lifecycle, and the way activities are launched and put together is a fundamental part of the platform's application model. For a detailed perspective on the structure of an Android application and how activities behave, please read the Application Fundamentals and Tasks and Back Stack developer guides.

You can also find a detailed discussion about how to create activities in the Activities developer guide.

Fragments

Starting with HONEYCOMB, Activity implementations can make use of the Fragment class to better modularize their code, build more sophisticated user interfaces for larger screens, and help scale their application between small and large screens.

Activity Lifecycle

Activities in the system are managed as an activity stack. When a new activity is started, it is placed on the top of the stack and becomes the running activity -- the previous activity always remains below it in the stack, and will not come to the foreground again until the new activity exits.

An activity has essentially four states:

If an activity in the foreground of the screen (at the top of the stack), it is active or running.
If an activity has lost focus but is still visible (that is, a new non-full-sized or transparent activity has focus on top of your activity), it is paused. A paused activity is completely alive (it maintains all state and member information and remains attached to the window manager), but can be killed by the system in extreme low memory situations.
If an activity is completely obscured by another activity, it is stopped. It still retains all state and member information, however, it is no longer visible to the user so its window is hidden and it will often be killed by the system when memory is needed elsewhere.
If an activity is paused or stopped, the system can drop the activity from memory by either asking it to finish, or simply killing its process. When it is displayed again to the user, it must be completely restarted and restored to its previous state.

The following diagram shows the important state paths of an Activity. The square rectangles represent callback methods you can implement to perform operations when the Activity moves between states. The colored ovals are major states the Activity can be in.

There are three key loops you may be interested in monitoring within your activity:

The entire lifetime of an activity happens between the first call to onCreate(Bundle) through to a single final call to onDestroy(). An activity will do all setup of "global" state in onCreate(), and release all remaining resources in onDestroy(). For example, if it has a thread running in the background to download data from the network, it may create that thread in onCreate() and then stop the thread in onDestroy().
The visible lifetime of an activity happens between a call to onStart() until a corresponding call to onStop(). During this time the user can see the activity on-screen, though it may not be in the foreground and interacting with the user. Between these two methods you can maintain resources that are needed to show the activity to the user. For example, you can register a BroadcastReceiver in onStart() to monitor for changes that impact your UI, and unregister it in onStop() when the user no longer sees what you are displaying. The onStart() and onStop() methods can be called multiple times, as the activity becomes visible and hidden to the user.
The foreground lifetime of an activity happens between a call to onResume() until a corresponding call to onPause(). During this time the activity is in front of all other activities and interacting with the user. An activity can frequently go between the resumed and paused states -- for example when the device goes to sleep, when an activity result is delivered, when a new intent is delivered -- so the code in these methods should be fairly lightweight.

The entire lifecycle of an activity is defined by the following Activity methods. All of these are hooks that you can override to do appropriate work when the activity changes state. All activities will implement onCreate(Bundle) to do their initial setup; many will also implement onPause() to commit changes to data and otherwise prepare to stop interacting with the user. You should always call up to your superclass when implementing these methods.