How can Java assignment be made to point to an object instead of making a copy?

Question

In a class, I have:

private Foo bar;
public Constructor(Foo bar)
{
    this.bar = bar;
}

Instead of creating a copy of bar from the object

Answer 1

To get that behavior you could modify a member of an object:

public class Number{
  int value;
  Number(int value){
    this.value = value;
  }
  public String toString() {
    return "" + value;
  }
}

You could then do:

Number x = new Number(7);
Number y = x;
x.value = 9;
System.out.println(y);//prints 9