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AbstractList equals() method in Java with Examples

  • Last Updated : 26 Nov, 2018

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:

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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



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