Ultimate Java Programming

Java V.S. JavaScript

2011-05-23T14:42:00.000-06:00

In this post we will be covering the difference between Java and JavaScript. If you want the simple answer here it is, Java and JavaScript are two completely different things! Java is a computer programming language to build computer applications. JavaScript is also a computer programming language but that's where the similarities end. JavaScript is used inside of web site coding to add additional features such as surveys while Java is used to build applications.

Both languages are OOP (object oriented programming) but JavaScript was developed by Netscape and was originally called LiveScript. On the other hand Java was invented by James Gosling at Sun micro systems. Another difference is that while Java can stand on its own, JavaScript(or LiveScript) needs to be placed within and HTML document to function at all. LiveScript was renamed JavaScript because at the time of creation Java was(and still is) one of the most popular coding languages. So JavaScript replaced the name of LiveScript for marketing reasons.

So for those of you who have heard of Java and JavaScript I hope this post clears up the confusion. JavaScript is a web site code script and is dependant on HTML(hyper link mark-up language) to run. Java can stand alone and is used to build applications. Java and JavaScript are completely different!

If you have any questions on Java V.S. JavaScript feel free to leave a comment. Also if you have an idea for a future post feel free to leave a comment. Well, that wraps it up for this post, see you in the next!

Intro to the switch statement

2011-05-22T20:19:00.000-06:00

In this post we will be covering the switch statement. A switch statement is a more efficient way to write large amounts of if statements. This is useful when you have a program that asks the user for age, weight, height or any other variable that differs for every person and then does something different depending on that variable. Without switch statements you would have to write if statements for any possible weight which would take forever. That’s where the power of switch statements comes in. Let’s begin!

import java.util.Scanner;

public class Advice_Generator {

public static void main(String[] args){

Scanner a = new Scanner(System.in);

int weight;

weight = a.nextInt();

if(weight == 60){System.out.print(weight);}

if(weight == 61){System.out.print(weight);}

if(weight == 62){System.out.print(weight);}

}

As seen above, we would have to write an if statement for every possible weight. The switch statement makes this a little easier.

import java.util.Scanner;

public class Advice_Generator {

public static void main(String[] args){

Scanner a = new Scanner(System.in);

int weight;

System.out.println("Enter weight");

weight = a.nextInt();

switch(weight){

case 60:System.out.println("Eat more, you are to light!");

case 61:System.out.println("Eat more, you are to light!");

case 62:System.out.println("Eat more, you are to light!");

case 63:System.out.println("Eat more, you are to light!");

case 64:System.out.println("Eat more, you are to light!");

case 65:System.out.println("Eat more, you are to light!");

case 66:System.out.println("Eat more, you are to light!");

case 67:System.out.println("Eat more, you are to light!");

case 68:System.out.println("Eat more, you are to light!");

case 69:System.out.println("Eat more, you are to light!");

case 70:System.out.println("Eat more, you are to light!");

case 71:System.out.println("Eat more, you are to light!");

case 72:System.out.println("Eat more, you are to light!");

case 73:System.out.println("Eat more, you are to light!");

case 74:System.out.println("Eat more, you are to light!");

case 75:System.out.println("If you are a child, you are ok.");

case 76:System.out.println("If you are a child, you are ok.");

case 77:System.out.println("If you are a child, you are ok.");

case 78:System.out.println("If you are a child, you are ok.");

case 79:System.out.println("If you are a child, you are ok.");

case 80:System.out.println("If you are a child, you are ok.");

}

We are creating a switch statement for the variable weight and then creating different cases for whatever the variable might be. So if you are 74 pounds or under it would say Eat more. This could be done more efficiently with an if statement(if(weight >74){

System.out.println("If you are a child, you are ok.");

} )

If statements are better if you have a range you want to do something for, but if you have an application that needs to do something different each time a switch statement is better. For example a child likes and does different things at each age so a switch statement would be better, but if you were doing a application deciding if someone had to go to the gym, and if statement would be better because at a certain range you should go to the gym. You would go to the gym if you 5000 pounds and anywhere above so an if statement is better. Deciding whether to use an if statement or a switch statement simply depends on the goal of the application you are trying to build.

If you have any questions on switch statements or any other topic feel free to leave a comment. Also if you have any ideas for future posts or things that you feel I can improve on, feel free to leave a comment. Well, that wraps it up for this post, see you in the next!

Intro to logic operators

2011-05-22T17:16:00.000-06:00

In this post we will be covering logic operators, what they are, how to use them, and what they are most commonly used for. A logic operator is a statement that helps the computer decide what to do and when to do it. Logic operators can be used in a variety of things but are commonly used in if else statements.

When using an if else statements you have to put a condition in the parameters of the statement like so:

public class Main {

public static void main(String[] args){

int x=1;

if(x==1){ System.out.println("x is 1");

}else{

System.out.println("x is not 1");

}

Here you are asking the computer what x is and depending on what x is do something, but what if you have two conditions that need to be true? We can write two if statements to make something happen for both as seen below, but what if we only want it to print out “Hello World x + y” if x=1 and y=2?

public class Main {

public static void main(String[] args){

int x=1;

int y=2;

if(x==1){

System.out.println("Hello World,x");

}else{

System.out.println("Conditions are not true");

}

if(y==2){

System.out.println("Hello World ,y");

}else{

System.out.println("Conditions are not true");

}

Well, that’s where logic operators come into play! With the power of a logic operator we can type something like this:

public class Main {

public static void main(String[] args){

int x=1;

int y=2;

if(x==1 && y==2){

System.out.println("Hello World x + y");

}else{

System.out.println("Conditions are not true");

}

We can use a double & sign to only do something if both sides of the condition are true(x is 1 and y is 2). Another great part is that we can add in as many double & signs as we want so if we wanted to make an example like this we could:

public class Party {

public static void main(String[] args){

boolean tim = true;

boolean bob = true;

boolean jim = false;

boolean john = true;

boolean James = true;

boolean Parker = false;

if(tim == true && bob == true && jim == true && john == true && James == true && Parker == true){

System.out.println("Full Party!!");

}else{

System.out.println("Some could not make it to the best party ever.....");

}

Here we make a simple party application to test if everybody showed up. We declare a bunch of boolean(true of false) names. True if they showed up, false if they didn’t. Some of the names are set to true some to false. We don’t need to declare the ones that are false because if we don’t declare them true booleans have a default value of false, but we set some to false just because. The end result will be “Some could not make it to the best party ever…….” Because some didn’t come. How do we use logic operators some only some have to come? Well lets say that you only want your best buds to come over, but they all invited people also so really its fine if only James and Tim come over(because they are your best buds!), but its ok with you if some other friends to come over. To make a logic operator that only needs James and Tim to come over, but will accept other friends would look like this:

public class Party {

public static void main(String[] args){

boolean tim = true;

boolean bob = true;

boolean jim = false;

boolean john = true;

boolean James = true;

boolean Parker = false;

if(tim == true && James == true || bob == true && jim == true && john == true){

System.out.println("Great party");

}else{

System.out.println("Man.... hardly anyone showed up.... ): ");

}

The computer will print out great party if only tim and James comes over OR if bob, jim , and john come over. Otherwise hardly anyone came to your party. The double pipe keys ( | ) are right below your backspace key on most keyboards and indicate an or statement. So if this side of the argument is true do it, if the other side is true do it, if only one side is true do it, if both are true do it. If both sides are false don’t do it, but with the double & signs both sides must be true to continue the action. Remember, one = sign is assigning a value two = signs are checking the value!

If you have any questions or ideas for future posts feel free to leave a comment below! Well, that wraps it up for this post, see you in the next!

Intro to GUI

2011-05-20T16:38:00.000-06:00

In this post we will cover basics of GUI's(graphical user interface). In this post we will build a frame with a text area. Well, lets begin!

import javax.swing.*;

public class Main {

public static void main(String[]args){

JFrame frame = new JFrame("The title bar");

JTextArea text = new JTextArea();

frame.setSize(300,300);

frame.setVisible(true);

frame.getContentPane().add(text);

frame.setdefaultcloseoperation(JFrame.EXIT_ON_CLOSE);

}

In this code we are importing the javax.swing package( the * means import everything in the package), declaring a new JFrame variable named frame(a JFrame is a frame or window), Creating a text area named text, setting the size to 300 300(300 pixels in width, 300 pixels in height), and finally getting the content pane of the frame(think of the frame as a window pane and we are painting(adding) test to fill the window pane. When you build and compile this program no matter how to alter the dimensions of the frame the text area will always fit the size of the frame. This is because we added text to the whole frame(in later posts we will learn how to control placement and size of things such as text areas) so the size of the frame is the size of text.

If you have any questions on GUI's or ideas for future posts feel free to leave a comment below! Well, that wraps it up for this post, see you in the next!

Intro to the Do While loop

2011-05-20T16:23:00.000-06:00

In this post we will be covering the do while loop. This loop is useful when you want to do something at least once but might have to do it more then once. Well, lets begin!

public class Main{
public static void main(String[] args){
boolean x = true;
do{
System.out.println(x);

}while(x = false);
}
}

In this code we are creating a boolean(true or false) variable x and declaring it true. We then create a do while loop thats says do this while this is true or false. Because the JVM(java virtual machine, the thing that runs your application) reads from top to bottom it will print the value of x(true) and then look at the while condition. The JVM stops looping because it sees that x = true and not x = false but it read from top to bottom,so it did it at least once before stopping.

If you have any questions on do while loops or any ideas for future posts feel free to leave a comment below.
Well, that wraps it up for this post, see you in the next!

Intro to if else statements

2011-05-20T11:13:00.000-06:00

In this post we are covering the if else statement.

public class Main{
public static void main(String[] args){
int x = Math.random()*20;
if(x ==1){
System.out.println("X = 1");
}else{System.out.println(x);

}
}
}

In this code we are generating a random number(x) and writing a simple if else statement saying, if x = 1 print x =1. Else(if x is anything but 1) print the value of x. We need the two = signs so the computer knows you are comparing and checking the value of x and not assigning the value of x to 1. If you have any questions or ideas for future posts feel free to leave them below! The purpose of an if else statement is so if something is true do this, but we dont want to write a bunch of if statements for each posibility so we use the else statement to catch all other posibilities.

Well, that wraps it up for this post, see you in the next!

Random Numbers in Java

2011-05-20T09:30:00.000-06:00

In this post we will be covering random number generation. This is really simple so this post will be rather short. Well, lets begin!

public class Main{
public static void main(String[] args){
int a = Math.random()*5;
System.out.println(a);
}
}

This is all great and everything, but you want to find a reason to use this number right? Well lets build a simple game.

import java.util.*;
public class Main{
public static void main(String[] args){
for(int i =0; i>5;){
int x = Math.random()*5;
int guess;
Scanner a = new Scanner(System.in);
guess = a.nextint();
if(x = guess){
System.out.println("correct");
}else{
System.out.println("Incorrect");
}

}

}
}

This generates a random number and then we create a new scanner(for user input) and then we save the input in the variable guess. We have an if else statement that determines whether or not guess is equal to x(random number).

That wraps it up for this post, see you in the next!

The While loop

2011-05-20T09:18:00.000-06:00

In this post we will be covering the while loop. A while loop is a block of code you want to loop through, but you don't know how many times you want to loop through. A while loop is good for looping when you only want to loop when a condition is true.

public class Main{
public static void main(String[] args){
boolean print = true;
while(print = true){
System.out.println("Print = true);

}

}
}
We don't know for how long we want the print variable to remain true, so we use a while loop(While print = true) print "Print = true"(because it is). So once again while loops are good when you have a variable that is always changing and you only want to do something if something else is true. This code would run forever though, because we keep the print variable true forever but for the purpose of this example that's ok.

If you have any questions or ideas for future posts, feel free to leave a comment below. Well that wraps it up for this post, see in the next!

The for Loop

2011-05-20T09:07:00.000-06:00

In this post we will be covering the for loop. The for loop is a block of code that can repeat itself for a set amount of repeats. A for loop is useful when you know exactly how many times you need to loop through(v.s. a while loop). Well, lets begin!

public class main{
public static void main(String[] args){
for(int i = 0;i<20;i++;){
System.out.println(i + " Hello World");
}
}
}
so in this code we are declaring a class, declaring our main method and building a for loop.
We tell the computer we want to use int(a number) i for our variable, loop for as long as i<20, and after done with each loop add 1 to i (or we would loop forever).

If you ran this code though, you would see

0 Hello World
1 Hello World
2 Hello World
3 Hello World
4 Hello World
5 Hello World
6 Hello World
7 Hello World
8 Hello World
9 Hello World
10 Hello World
11 Hello World
12 Hello World
13 Hello World
14 Hello World
15 Hello World
16 Hello World
17 Hello World
18 Hello World
19 Hello World

You may be wondering, "Why does it only loop to 19 when we told to go to 20?" it does this because in java
the computer counts zero as its first number. If you have any questions or ideas for future posts feel free to leave a comment below.

That wraps it up for for loops! See you in the next post.

Our first program!

2011-05-16T20:04:00.001-06:00

In this post we will be building our first Real Java program! The program will ask the user for his name, and his favorite food. Let’s begin by opening Eclipse. Click File, new, Java project. In the popup leave everything as defaults and then name your project Test and hit finish. Right click on the SRC folder and click new class. Name the class Main

Put this into your main class so it looks like this.

import java.util.Scanner;

public class Main {

public static void main(String[] args){

}

We will start at the top and work our way down.

import java.util.Scanner;

here we are importing the Scanner class from the java.util package. You might be asking, but we never downloaded a java.util package. Well actually in comes with the JDK. A Scanner is something that can get input from the keyboard.

public class Main {

}

Declaring our class public(available to be viewed by other classes) declaring it a class, and declaring its name. The curly braces are used to define the classes body(where you put stuff to make stuff happen).

public static void main(String[] args){

}

Our main method.

METHOD: What the class uses to make something happen. A procedure for accomplishing something.

Declaring the method public.

Declaring it static(will cover this later) Declaring it void(does not return anything)

Declaring that it’s our main method.

We will cover this in greater detail in later posts, but for now just put it.

Scanner name = new Scanner(System.in);

Scanner food = new Scanner(System.in);

String username;

String favoritefood;

Declaring two new Scanner variables name and food. Then declaring two strings(strings are text) and naming them username and favorite food.

System.in: telling the program that the scanner needs to take something in(the users name, and his favorite food).

import java.util.Scanner;

public class Main {

public static void main(String[] args){

Scanner name = new Scanner(System.in);

Scanner food = new Scanner(System.in);

String username;

String favoritefood;

System.out.println("What is your name");

username = name.next();

System.out.println(username + " What is your favorite food?");

favoritefood=food.next();

System.out.println("So " + username + " your favorite food is "+ favoritefood );

}

Our finished code. Don’t worry we will go over it! We are printing “What is your name” and then telling the system that username is equal to name(don’t worry about the .next() ). The Scanner name needs to take something in so that’s where you come in. The system will wait until you type something in to take the space of the Scanner name. Then we print the String username(the users name which is equal to the text you put in). Put a space before the W or it will run together like this: TimWhat is your favorite food? The system waits again until you type something in for the users favorite food. Finally it prints out “So ” + username “ What is your favorite food is” + favoritefood.

Type this into eclipse and click the run button. The box at the bottom serves as the command prompt box in eclipse. This is where you will type in your name and favorite food when prompted.

Well, that finishes up this post. If you guys have any ideas or questions feel free to leave a comment!

The java JDK and Eclipse IDE

2011-05-16T15:27:00.000-06:00

In this post we will be installing the java JDK (java development kit, needed to run everything java.) and Eclipse IDE (Integrated development environment) for easier programming and running. We will be installing on windows. The JDK should already be installed if you have a Mac.

Let’s get started! First we will download the java JDK, the website is always changing so just Google java JDK download. It should be the first one on the list, click it. Once the page is brought up download the JDK (Make sure to get the standard edition or enterprise edition! Never get the micro edition!) Once you have run the installer wizard go into the place in which you installed it (program files or program files(x86), go into java, then click on JDK. Go into bin and right click on the first one on the list. Once right clicked click on properties and copy the location of it.

Next go into the start menu and click on control panel, system and security, and then system.
You should see on the left a panel labeled control panel home. Click on advanced system settings from this panel. From the pop up click environment variables. Under user variables click new.
This part is very important! For the variable name you must name it: Path
The P in path must be capitalized! Then for variable value paste in the location directory, and click ok. To test if it is installed correctly open command prompt and enter JAVAC. If a bunch of stuff comes up you did it correctly!

Now to install Eclipse. This installation is a bit simpler. Go to http://www.eclipse.org/downloads/
and click Eclipse IDE for Java developers, or Eclipse IDE for Java EE developers depending on what type of JDK you downloaded. There is little difference between EE and SE so don’t freak out and download the EE because you think it’s better.
Once downloaded it should run an install wizard. Click next a bunch and then open the eclipse exe. You might want to move this to the desktop for easy access. To do this right click it, click send to and then click desktop. DONT DRAG AND DROP IT!
Once you open up eclipse go into window, click on preferences, type in text, click on text editors, and click the box that reads: Show line numbers
Finally click apply then ok.

Well, that wraps it up for this post, in the next one we start programming! You may have already read the other post where we print “hey” on the screen. Well in the next post we actually build something sort of cool. I made the “hey” one first so you might have had trouble getting it to work because you didn’t have the JDK.

The very beginning(see java JDK post first)

2011-05-16T14:35:00.000-06:00

In this post we will be building a simple java program.
Before this you will need to download and install the java JDK.
This is available for download at http://oracle.com
You may have to look up other tutorials on installing this, or I might do a post on it.

After you do this open up any basic text editor. Lets begin with the basics of java, a class. Type this code into your text editor:

public class pear{
public static void main(String[] args){
System.out.println("Hey");

}
}

Lets work our way from the top down.
PUBLIC: declaring the class available to look at by other classes.
CLASS:base of a java application.Java is built out of classes.
PEAR:what we named the class.
PUBLIC STATIC VOID MAIN(STRING[] ARGS): our main method, in later posts we will be going over this.
SYSTEM:telling the system to do something.
OUT:telling the system to put something out.
PRINTLN:telling the system to print something(the LN is stands for next line).

Lets save this to the desktop for easy access.When saving save the file name as this:pear.java, then save it as an all file type.Next go into command prompt and type:
cd desktop

then type:

Javac pear.java

now on your desktop you should have a .class
now in command prompt type:
java pear

the words "hey" should appear. I know this isnt a super sweet java application, but you have to start somewere!