Comparing two ArrayList In Java
- Difficulty Level : Basic
- Last Updated : 04 Dec, 2020
Java provides a method for comparing two Array List. The ArrayList.equals[] is the method used for comparing two Array List. It compares the Array lists as, both Array lists should have the same size, and all corresponding pairs of elements in the two Array lists are equal.
Example:
Syntax:
boolean equals[Object o]Parameters: This function has a single parameter which is an object to be compared for equality.
Returns: This method returns True if Array lists are equal.
Implementation:
Java
// Comparing two ArrayList In Java import java.util.ArrayList; public class GFG { public static void main[String[] args] { // create two Array List ArrayList ArrayList1 = new ArrayList[]; ArrayList ArrayList2 = new ArrayList[]; // insert items in AyyarList 1 ArrayList1.add["item 1"]; ArrayList1.add["item 2"]; ArrayList1.add["item 3"]; ArrayList1.add["item 4"]; // insert items in AyyarList 2 ArrayList2.add["item 1"]; ArrayList2.add["item 2"]; ArrayList2.add["item 3"]; ArrayList2.add["item 4"]; // Display both ArrayList System.out.println[" ArrayList1 = " + ArrayList2]; System.out.println[" ArrayList1 = " + ArrayList1]; // compare ArrayList1 with ArrayList2 if [ArrayList1.equals[ArrayList2] == true] { System.out.println[" Array List are equal"]; } else // else block execute when // ArrayList are not equal { System.out.println[" Array List are not equal"]; } // insert one more item in ArrayList 1 System.out.println[ "\n Lets insert one more item in Array List 1"]; ArrayList1.add["item 5"]; // display both ArrayList System.out.println[" ArrayList1 = " + ArrayList1]; System.out.println[" ArrayList = " + ArrayList2]; // again compare ArrayList 1 with ArrayList 2 if [ArrayList1.equals[ArrayList2] == true] { System.out.println[" Array List are equal"]; } else { System.out.println[" Array List are not equal"]; } } } |
Output ArrayList1 = [item 1, item 2, item 3, item 4]
ArrayList1 = [item 1, item 2, item 3, item 4]
Array List are equal
Lets insert one more item in Array List 1
ArrayList1 = [item 1, item 2, item 3, item 4, item 5]
ArrayList = [item 1, item 2, item 3, item 4]
Array List are not equal
Time Complexity: O[N], where N is the length of the Array list.