Whenever we add ‘final’ in front of a variable, it means we can’t change the variable under any circumstances. In this example we use an int variable number, but we write it as NUMBER so we know it’s a constant.
// jamesprogram.java class jamesprogram { public static void main (String[] args){ cat catObject = new cat(10); for (int i=0;i<5;i++){ catObject.add(); System.out.printf("%s", catObject); } } }
//cat.java public class cat { private int sum; // declare final variable // as soon as we assign something to NUMBER // (initialize it) it cannot be changed, EVER // after that point private final int NUMBER; // Contants are in caps public cat(int x){ NUMBER=x; } public void add(){ sum+=NUMBER; } public String toString(){ return String.format("sum = %d\n", sum); } }
Outputs:
sum = 10
sum = 20
sum = 30
sum = 40
sum = 50