In order to install Java on your computer you have to follow certain steps which are:-
Step 1:
Download Java Development Kit from Oracle website.Search for JDK on google or go to http://www.oracle.com/technetwork/java/javase/downloads and then click on JDK or Java platform. Then, accept the license and choose the correct JDK for your computer depending upon operating system you are using. For windows, in order to check for 64bit or 32bit Go to properties of 'This PC' and check.
Step 2:
Install the Java Development Kit software by opening the JDK installer and follow the easy steps.
Step 3:
[For windows]Set the Environment Variable Path to Java bin folder and locate where you have installed Java.By default it will be - C: ->Prgram Files->Java->JDK->bin.Your JDK version might change. Then go to Properties of 'This PC'->click on Advanced System Settings->Under Advanced Tab click on "Environment Variables"->Under System variables choose path->Add the location of the bin Java folder->click 'ok' to finish.
Check after installation
Java is now installed. To check open command prompt(for Windows) or terminal(for Mac OS) by right clicking on start then clicking on Command Prompt(for Windows ) or doing a spotlight search for the terminal(for Mac OS).After Command prompt is opened type javac and hit enter. You can see all options for Java compiler.