How to install Java in Linux

My system is rh9, the installation of the selected full installation, and then from the Internet under a j2sdk-1_4_2_05-linux-i586-rpm.bin, after installation
Use Java-version
I found that it was built on Linux.
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Java version "1.3.1"
Jdkgcj 0.2.3 (http://www.arklinux.org/projects/jdkgcj)
Gcj (GCC) 3.2.2 20030222 (Red Hat Linux 3.2.2-5)
Copyright (c) 2002 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is no
Warranty; not even for merchantability or fitness for a particle purpose.
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What should I do ???
 
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1. Install JDK
 
Download JDK directly from Sun: The http://java.sun.com/j2se/1.4.2/download.html provides two downloads:
 
1. rpm in self-extracting file (j2sdk-1_4_2_04-linux-i586.bin, 32.77 MB) This is a self-extracting file, installed on Linux as follows:
 
# Chmod U + X./j2sdk-1_4_2_04-linux-i586.bin
 
#./J2sdk-1_4_2_04-linux-i586.bin
 
After entering YES as prompted, JDK is decompressed to The./j2sdk1.4.2 _ 04 directory. In order to be consistent with the JDK installation path in the following 2, we will perform the following operations to establish the installation path under/usr/Java and test the file to this path:
 
# Mkdir/usr/Java
 
# Cp-Fr./j2sdk1.4.2 _ 04/usr/Java
 

 
2. rpm in self-extracting file (j2sdk-1_4_2_04-linux-i586-rpm.bin, 32.77 MB) This is also a self-extracting file, but the extracted file is a j2sdk-1_4_2_04-linux-i586-rpm package, run the RPM command to install it on Linux. The installation is as follows:
 
# Chmod U + X./j2sdk-1_4_2_04-linux-i586-rpm.bin
 
#./J2sdk-1_4_2_04-linux-i586-rpm.bin
 
# Rpm-IVH j2sdk-1_4_2_04-linux-i586-rpm
 
The installation software automatically installs JDK in the/usr/Java/j2sdk1.4.2 _ 04 directory.
 
2. Configure Environment Variables
 
1. Modify user environment variables
 
Assume that the Java User is kunp. Edit the user's. bashrc file to set environment variables.
 
# Vi/home/kunp/. bashrc
 
Add the following to the. bashrc file:
 
Export java_home =/usr/Java/j2sdk1.4.2 _ 04
Export classpath = $ classpath: $ java_home/lib: $ java_home/JRE/lib
Export Path = $ java_home/bin: $ java_home/JRE/bin: $ path: $ homr/bin
 
2. Modify the environment variables of all users
 
# Vi/etc/profile
 
Add:
 
Export java_home =/usr/Java/j2sdk1.4.2 _ 04
Export classpath = $ classpath: $ java_home/lib: $ java_home/JRE/lib
Export Path = $ java_home/bin: $ java_home/JRE/bin: $ path: $ homr/bin
 
Be sure to add $ classpath to the classpath path: Because I didn't add this stuff before, I always reported an error when interpreting and executing the class file.
 
Now let's see if Java is fully installed. Compile the most powerful Java file:
 
Hellodate. Java
 
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// Hellodate. Java
Import java. util. date;
 
Public class hellodate {
Public static void main (string [] ARGs ){
System. Out. println ("Hello, it's :");
System. Out. println (new date ());
}
}
 
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Compile and execute the file under the kunp User:
 
# Su-kunp
 
$ Javac hellodate. Java
$ Java hellodate
Hello, it's:
Thu Jun 10 14:21:21 CST 2004
 

 
OK. The Java environment has been set up. Start to write your Java program.