Enthuware

Since the declared type of the variable x1 is Object

Since the declared type of the variable x1 is X

X x1 = new X();

The Object version returns false because x1 and
x2 are pointing to two different objects.

class X{
	int val;
	public boolean equals(Object x){
		if( ! (x instanceof X) ) return false;
		//now compare the values of instance fields of this and x and return true/falseaccordingly
		return this.val == ((X) x).val;
	}
}

public class TestClass extends Test{
	
	
	public static void main(String[] args){

		X x1 = new X(); x1.val = 1;
		Object x2 = new X(); ((X) x2).val = 1;
		System.out.println(x1.equals(x2)); //what will it print?
	}
}

If you have understood the rules of method selection that we discussed in the “Working with
Methods and Encapsulation” chapter, you should be able to figure out that the above code will print
false. The compiler sees two versions of the equals method in class X to choose from when it tries
to bind the x1.equals(x2) method call - the version that class X inherits from java.lang.Object,
which takes Object as an argument and the version that class X implements itself, which takes X
as an argument. Since the declared type of the variable x2 is Object, the compiler binds the call
to the Object version instead of the X version. The Object version returns false because x1 and
x2 are pointing to two different objects.