Why he use `equals(other)` instead `obj.equals(other)`? when is appropriate to use it this way?

Question

I would like to know the difference between equals(other) and obj.equals(other).

public int compareTo(Object obj){ 
    Treet other = (Treet) obj; 
    if(equals(other)) {
        return 0;
    }
}

Answer 1 · 2017-01-27T17:50:37Z

January 27, 2017 5:50pm

If you're inside an instance method of an object, You can call it's instance method either by themselves, or prefixed with this

See below

public class Foo {
  private Bar bar;

  // In this method, we are *inside* an instance of Foo, so we can call instance methods
  // 'this', refers to the instance we are in, so it can also be used to call instance methods
  public void printYesIfEqual(Foo that) {
    if(equals(that)) {
      System.out.println("Yes!");
    }
    if(this.equals(that)) {
      System.out.println("Yes!");
    }
  }

  // In this method, we are *inside an instance of Foo, so we have access to it's 'bar' field
  // we are not however, *inside* of Bar, so to call instance methods of Bar, on our bar field
  // we need to use the '.' operator,
  // Like before, we can also access our bar field with 'this' to refer to the object that we are *inside*
  public void printYesIfSameBar(Bar otherBar) {
    if(bar.equals(otherBar)) {
      System.out.println("Yes!");
    }
    if(this.bar.equals(otherBar)) {
      System.out.println("Yes!");
    }
}

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Jorge Otero

Jorge Otero

Why he use `equals(other)` instead `obj.equals(other)`? when is appropriate to use it this way?

1 Answer

Samuel Ferree

Samuel Ferree

Jorge Otero

Jorge Otero