Install JDK 7 in Ubuntu and configure the default JDK version (openjdk6 by default)

CD/usr/lib
Sudo mkdir JVM

Sudo tar zxvf jdk-7-linux-i586.tar.gz-C/usr/lib/JVM
CD/usr/lib/JVM
Sudo MV jdk1.7.0/Java-7-sun

Modify Environment Variables

Vim ~ /. Bashrc

Export java_home =/usr/lib/JVM/Java-7-sun
Export jre_home =$ {java_home}/JRE
Export classpath =. :$ {java_home}/lib :$ {jre_home}/lib
Export path =$ {java_home}/bin: $ path

Add $ path. Otherwise, the system path will be overwritten.

 

Source ~ /. Bashrc

 

Configure the default JDK version

Sudo Update-alternatives -- install/usr/bin/Java/usr/lib/JVM/Java-7-sun/bin/Java 300
Sudo Update-alternatives -- install/usr/bin/javac/usr/lib/JVM/Java-7-sun/bin/javac 300
Sudo Update-alternatives -- install/usr/bin/Jar/usr/lib/JVM/Java-7-sun/bin/jar 300

Sudo Update-alternatives -- config Java 

Enter 1, 2, and 3 to represent the default JDK version.

Java-version

Java version "1.7.0 _ 03"
Java (TM) se Runtime Environment (build 1.7.0 _ 03-b04)

Java hotspot (TM) server VM (build 22.1-b02, mixed mode)

If Java: cannot execute binary file appears, it is generally an operating system version.