In Java, when the final keyword is used with variables of primitive data types (int, float, .., etc.), the value of the variable cannot be changed.

For example, the following program gives an error because i is final.

public class Test {
	public static void main(String args[]) {
		final int i = 10;
		i = 30; // Error because i is final.
	}
}

When the final is used with non-primitive variables (note that non-primitive variables are always references to objects in Java), the members of the referenced object can be changed. The final of non-primitive variables only means that they cannot be changed to refer to any other objects

class Test1 {
int i = 10;
}

public class Test2 {
	public static void main(String args[]) {
	final Test1 t1 = new Test1();
	t1.i = 30; // Works
	}
}