Install Java1.7

# apt-get update

# apt-get install openjdk- 7 -jdk

Switch

Change Java compiler:

# update-alternatives --config java

# update-alternatives --config javac

Select java 1.7:

 
           There are  
           2 
           choices  
           for 
            the alternative javac (providing /usr/bin/javac). 
          
           Selection    Path                                         Priority   Status 
          
           ------------------------------------------------------------ 
          
           0            
           /usr/lib/jvm/java- 
           6 
           -openjdk-amd64/bin/javac    
           1061      
           auto mode 
          
           1            
           /usr/lib/jvm/java- 
           6 
           -openjdk-amd64/bin/javac    
           1061      
           manual mode 
          
           *  
           2            
           /usr/lib/jvm/java- 
           7 
           -openjdk-amd64/bin/javac    
           1051      
           manual mode 
          
           Update also your .bashrc file with PATH variable. It must point to the  
           new 
           1.7 
            jvm : 
          
           #echo $PATH 
          
           /usr/lib/jvm/java- 
           1.7 
           . 
           0 
           -openjdk-amd64/bin:/usr/share/ant/bin 
          
           And source it to take changes into account 
          
           # source .bashrc