Property with same name in Child class java

Question

public class HelloWorld
{
  protected int num = 12;

  public void callme()
  {
    System.out.print(this.num);
  }

  public static void main(String[] args)
  {
    HelloWorld myObject1 = new HelloWorld();
    myObject1.callme();
    OtherClass myObject2 = new OtherClass();
    myObject2.callme();
  }
}


public class OtherClass extends HelloWorld
{
  protected int num = 14;
}

Why the output is "1212" instead of "1214"? In php its "1214" but not viceversa in java. What's the logic behind that?

Possible duplicate of https://stackoverflow.com/questions/12589274/slight-confusion-regarding-overriding-where-variables-are-concerned — vinS, Dec 10 '17 at 14:56

score 3 · Accepted Answer · answered Dec 10 '17 at 14:55

callme() method is defined only in the base class, and therefore return this.num; returns the instance variable of the base class.

There is no overriding of instance variables in Java.

If you'd override that method in the sub-class, by adding

public void callme()
{
    System.out.print(this.num);
}

to OtherClass, myObject2.callme(); will return 14, since it will execute callme() method of the sub-class, and therefore access the sub-class instance variable.

Property with same name in Child class java

1 Answers1