JuniorTheoryCommon

What does the program print?

JAVA

public class Main {
    public static void main(String[] args) {
        Box a = new Box(5);
        Box b = new Box(5);
        Box c = a;
        System.out.println(a.equals(b) + " " + a.equals(c));
    }
}

class Box { int n; Box(int n) { this.n = n; } }

false true

Expecting true true: without an override, equals comes from Object and compares references, so two boxes with the same n are not equal.
Expecting a compile error: every class inherits equals from Object, so it can be called on Box without writing it.

How do you make two Box objects with the same n equal?
Which method must be overridden together with equals?

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JuniorTheoryCommon

What does the program print?

JAVA

public class Main {
    public static void main(String[] args) {
        Box a = new Box(5);
        Box b = new Box(5);
        Box c = a;
        System.out.println(a.equals(b) + " " + a.equals(c));
    }
}

class Box { int n; Box(int n) { this.n = n; } }

false true

Expecting true true: without an override, equals comes from Object and compares references, so two boxes with the same n are not equal.
Expecting a compile error: every class inherits equals from Object, so it can be called on Box without writing it.

How do you make two Box objects with the same n equal?
Which method must be overridden together with equals?

Back to questions Open topic in roadmap →Answer it yourself — Quiz