Install JDK 1.6 in Ubuntu and set it to the default JDK 1. download the Liunx JDK in Windows, my jdk-6u43-linux-i586.bin2. upload JDK to Ubuntu3. manually install JDK through secureCRT (I installed under/usr/local/bin/jdk1.6.0 _ 43): First modify the permission sudo chmod u + x jdk-6u43-linux-i586.bin to install sudo-s. /jdk-6u43-linux-i586.bin4. configure the environment variable to open the profile file sudo nano/etc/profile and add # author ylchou # date 2013-06-23export JAVA_HOME =/usr/local/bin/jdk1.6.0 _ 43 export CLASSPATH = ".: $ JAVA_HOME/lib: $ CLASSPATH "e Xport PATH = "$ JAVA_HOME/: $ PATH" 5. manually set the system default JDK and enter the following commands on the terminal: sudo update-alternatives -- install/usr/bin/java/usr/local/bin/jdk1.6.0 _ 43/bin/java 300 sudo update-alternatives -- install/usr/bin/javac javac/usr/local/bin/jdk1.6.0 _ 43/bin/javac 300 sudo update-alternatives -- install/usr/bin/jar/usr/local/bin/jdk1.6.0 _ 43/ bin/jar 300 sudo update-alternatives -- install/usr/bin/javah/usr/local/B In/jdk1.6.0 _ 43/bin/javah 300 sudo update-alternatives -- install/usr/bin/javap/usr/local/bin/jdk1.6.0 _ 43/bin/javap 300 and then execute run the following code to select the JDK version we have installed: sudo update-alternatives -- config java6. verify that JDK is installed successfully. Restart the Shell terminal and run "java-version". If you enter the following command, the installation is successful: java version "1.6.0 _ 43" Java (TM) SE Runtime Environment (build 1.6.0 _ 43-b01) Java HotSpot (TM) Client VM (build phases 14-b01, mixed mode, sharing)