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Java Java Data Structures Organizing Data Interfaces

Raquel Smith
Raquel Smith
10,683 Points

How does equals(other) compare to the object passed in?

I am confused about how the equals(other) method is working here. I understand that we cast the obj Object as a Treet called other, but the if (equals(other)) statement doesn't take obj at all. How can you compare other and obj if you don't pass both to the equals() method?

For reference, the full code in the video is:

public int compareTo(Object obj) {
    Treet other = (Treet) obj;
    if(equals(other)) {
        return 0;
    //and then more stuff here

1 Answer

Equals is looking at the current instance of the Treet class vs. Object obj. If you were outside of the class, you would use


but since you're inside the Treet class Java knows you're using equals on the current instance. You could also use


and you would get the same result.