Java EE (Java Enterprise Edition) General Discussion

public class Tester{
	public static void changeValue( Integer a, int b ){
		a.valueOf(b);
	}
	
	public static void main( String[] args ){
		Integer a = new Integer(15);
		Tester.changeValue(a, 20);
		System.out.println(a); // It will print to screen the value 15, but i want it is 20.
	}
}