All and Sundries

Using lambda expression to read a csv file

2014-04-02T20:04:00.003-07:00

An old fashion way: using BufferedReader

For example, read a csv file, using first column as key and second column as value

Map<String, String> map=new HashMap<>();

BufferedReader br = new BufferedReader(new FileReader(PATH_TO_YOUR_FILE));

String line="";

while((line=br.readLine())!=null){

String tmp[] = line.split(",");

map.put(tmp[0],tmp[1]);

... THINGS YOU WANT TO DO ...

}

br.close();

A fancy way: using Stream

Map<String, String> map = Files.lines(Paths.get(PATH_TO_YOUR_FILE))

.map(line -> line.split(","))

.collect(Collectors.toMap(

array -> array[0],

array -> array[1]

));

Hadoop on Rocks Cluster

2013-07-08T21:09:00.001-07:00

build hadoop from source
chmod -R 755 /state/partition1/data/hadoop/

conf/master
light

conf/slave
light
compute-0-1
...
compute-0-10

==> conf/core-site.xml <==
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>



<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://light:54310/</value>
</property>
<property>
<name>df.permissions</name>
<value>false</value>
</property>
</configuration>

==> conf/hdfs-site.xml <==
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>



<configuration>
<property>
<name>dfs.name.dir</name>
<value>/state/partition1/data/hadoop/name</value>
<description> </description>
</property>
<property>
<name>dfs.data.dir</name>
<value>/state/partition1/data/hadoop/data</value>
<description> </description>
</property>
</configuration>

==> conf/mapred-site.xml <==
<?xml version="1.0"?>
<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>



<configuration>
<property>
<name>mapred.job.tracker</name>
<value>light:54311</value>
</property>
</configuration>

透過 mac os x internet sharing 讓 PC 使用網路連線

2013-06-16T18:52:00.003-07:00

目的：因為 pc 無法連線到 vpn server，但 mac 可以，所以想利用 mac 的網路連線，讓 pc 也能連入 vpn。
做法：因為 Mac Pro 有二個網路孔，所以讓 pc 能透過 mac 的第二個網路孔連線到 vpn

假設 mac 上的 vpn 設定已經完成。

Open "System Preferences"
Select "Sharing"
Select your VPN connection from the list of "Share your connection from:"
Select "Ethernet 2" in the checkboxes of "To computers using:"
Turn on "On" checkbox of "Internet Sharing" from the Service list.
Connect Ethernet cable between Mac's Port 2 and PC's port
Connect VPN server in Mac
Ping a VPN server, to make sure the connection between PC and VPN server is working

Mac OS X 的垃圾桶清不掉嗎？

2012-06-19T18:00:00.002-07:00

Cmd +Option + Shift + Backspace

Convert PNGs to Animated GIF

2012-05-17T06:53:00.002-07:00

convert -delay 5 *.png animated.gif

在 Java runtime exec 裡使用 pipe

2012-05-02T08:17:00.002-07:00

String[] cmd = {
"/bin/sh",
"-c",
"ls /etc | grep release"
};
Process p = Runtime.getRuntime().exec(cmd);