Every variable must have a data type. A variable's data type determines the values that the variable can contain and the operations that can be performed on it.

The Java programming language has two categories of data types: primitive and reference.

Objects, instantiations of classes, are reference data types.

This is a technique to change the data type of a primitive variable for the current operation only.

Example 1:

       double height = 60.45;

       System.out.println((int) height); would be used to print the integer portion of the height 

Example 2:

      int a = 10;

      int b = 3;

      System.out.println (a/b):       will print 3

      System.out.println ((double)a/b) will print 3.3333