AbstractList equals() method in Java with Examples

The equals() method of java.util.AbstractList class is used to compare the specified object with this list for equality. Returns true if and only if the specified object is also a list, both lists have the same size, and all corresponding pairs of elements in the two lists are equal. (Two elements e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)).) In other words, two lists are defined to be equal if they contain the same elements in the same order.

Syntax:

public boolean equals(Object o)

Parameters: This method takes the object o as a parameter to be compared for equality with this list.

Returns Value: This method returns true if the specified object is equal to this list.

Below are the examples to illustrate the equals() method.

Example 1:

// Java program to demonstrate
// equals() method
// for String value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // Creating object of AbstractList<String>
            AbstractList<String>
                arrlist1 = new ArrayList<String>();

            // Populating arrlist1
            arrlist1.add("A");
            arrlist1.add("B");
            arrlist1.add("C");
            arrlist1.add("D");
            arrlist1.add("E");

            // print arrlist1
            System.out.println("First ArrayListlist : "
                               + arrlist1);

            // Creating another object of AbstractList<String>
            AbstractList<String>
                arrlist2 = new ArrayList<String>();

            // Populating arrlist2
            arrlist2.add("A");
            arrlist2.add("B");
            arrlist2.add("C");
            arrlist2.add("D");
            arrlist2.add("E");

            // print arrlist2
            System.out.println("Second ArrayList : "
                               + arrlist2);

            // comparing first ArrayList to another
            // using equals() method
            boolean value = arrlist1.equals(arrlist2);

            // print the value
            System.out.println("Are both list equal : "
                               + value);
        }

        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

First ArrayListlist : [A, B, C, D, E]
Second ArrayList : [A, B, C, D, E]
Are both list equal : true

Example 2:

// Java program to demonstrate
// equals() method
// for Integer value

import java.util.*;

public class GFG1 {
    public static void main(String[] argv)
        throws Exception
    {

        try {

            // Creating object of AbstractList<Integer>
            AbstractList<Integer>
                arrlist1 = new ArrayList<Integer>();

            // Populating arrlist1
            arrlist1.add(10);
            arrlist1.add(20);
            arrlist1.add(30);
            arrlist1.add(40);
            arrlist1.add(50);

            // print arrlist1
            System.out.println("First ArrayListlist : "
                               + arrlist1);

            // Creating another object of AbstractList<Integer>
            AbstractList<Integer>
                arrlist2 = new ArrayList<Integer>();

            // Populating arrlist2
            arrlist2.add(10);
            arrlist2.add(20);
            arrlist2.add(30);

            // print arrlist2
            System.out.println("Second ArrayList : "
                               + arrlist2);

            // comparing first ArrayList to another
            // using equals() method
            boolean value = arrlist1.equals(arrlist2);

            // print the value
            System.out.println("Are both list equal : "
                               + value);
        }

        catch (NullPointerException e) {
            System.out.println("Exception thrown : " + e);
        }
    }
}

Output:

First ArrayListlist : [10, 20, 30, 40, 50]
Second ArrayList : [10, 20, 30]
Are both list equal : false