ubuntu 14.04 java installing using apt-get

there are three ways installing java.
1.default-jre/jdk
2. open-jdk
2. oracle java

1. default jre/jdk

sudo apt-get install default-jre default-jdk

2. openjdk-7-jre/jdk

sudo apt-get install openjdk-7-jre openjdk-7-jdk

3. oracle java

sudo apt-get install python-software-properties
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update

sudo apt-get install oracle-java6-installer

sudo apt-get update
sudo apt-get install -f oracle-java7-installer

sudo apt-get install -f oracle-java8-installer

* switching jdks using update-alternatives between jdks

sudo update-alternatives --config java 

REF
- http://askubuntu.com/questions/163429/error-when-installing-oracle-java7-installer
- http://stackoverflow.com/questions/22541853/oracle-java-7-installation-in-ubuntu-e-sub-process-usr-bin-dpkg-returned-an-er/22955890#22955890