What is Objects.equals in Java?

The equals() method is a static method of the Objects class that accepts two objects and checks if the objects are equal.

  • If both the objects point to null, then equals() returns true.
  • If any one of the objects points to null, then equals() returns false.
  • If both the objects are equal, then equals() returns true.
  • Otherwise, we use the equals method of the first argument to determine equality.

To learn more about the equals method of the Objects class, refer here.

Syntax

public static boolean equals(Object a, Object b)

Parameters

  • Object a: first object.

  • Object b: second object.

Return value

The method returns true if the objects are equal; otherwise, equals returns false.

Code

Example 1

In the code below, we pass null as an argument to the equals method. The method should return true, as both the input objects are null.

import java.util.Objects;
public class main {
    public static void main(String[] args) {
        boolean equalityCheck = Objects.equals(null, null);
        System.out.println("The Objects.equals() method returns '" + equalityCheck + "' when the passed objects are null");
    }
}

Example 2

In the code below, we pass null as one of the arguments for the method. The method should return false, as one of the input objects is null.

import java.util.Objects;
public class main {
    public static void main(String[] args) {
        boolean equalityCheck = Objects.equals(null, 4);
        System.out.println("The Objects.equals() method returns '" + equalityCheck + "' when null is passed as the first object.");
        equalityCheck = Objects.equals(4, null);
        System.out.println("The Objects.equals() method returns '" + equalityCheck + "' when null is passed as the second object.");
    }
}

Example 3

In the code below, we define a class Temp with attributes a and b. The methods toString(), hashCode, and equals are overridden in the class that has custom implementation.

Here, the equals method is overridden in the Temp class and checks if the objects have the same values for the attributes a and b.

  • We create three different instances of the Temp class, temp1, temp2, and temp3.
  • The instances temp1 and temp2 have the same values for the attributes a and b. Hence, passing temp1 and temp2 as parameters to the method should return true, as the values of the attributes of the objects are equal.
  • The instances temp2 and temp3 have different values for the attributes a and b. Hence, passing temp2 and temp3 as parameters to the method should return false, as the values of the attributes of the objects are not equal.
import java.util.Objects;
public class main {
    static class Temp{
        private int a, b;
        public Temp(int a, int b) {
            this.a = a;
            this.b = b;
        }
        @Override
        public String toString() {
            return "Temp{" +
                    "a=" + a +
                    ", b=" + b +
                    '}';
        }
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Temp temp = (Temp) o;
            return a == temp.a && b == temp.b;
        }
        @Override
        public int hashCode() {
            return Objects.hash(a, b);
        }
    }
    public static void main(String[] args) {
        Temp temp1 = new Temp(2,3);
        Temp temp2 = new Temp(2,3);
        Temp temp3 = new Temp(5,4);
        System.out.println(Objects.equals(temp1, temp2));
        System.out.println(Objects.equals(temp2, temp3));
    }
}
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