1. Compare two arraylists for equality
Java program to test if two given lists are equal. To test equality –
- Sort both lists.
- Compare both lists using equals[] method.
List.equals[] method return true if both elements are of same size and both contains same set of elements in exactly same order.
public class ArrayListExample { public static void main[String[] args] { ArrayList listOne = new ArrayList[Arrays.asList["a", "b", "c", "d", "f"]]; ArrayList listTwo = new ArrayList[Arrays.asList["a", "b", "c", "d", "e"]]; Collections.sort[listOne]; Collections.sort[listTwo]; //Compare unequal lists example boolean isEqual = listOne.equals[listTwo]; //false System.out.println[isEqual]; //Compare equals lists example ArrayList listThree = new ArrayList[Arrays.asList["a", "b", "c", "d", "f"]]; isEqual = listOne.equals[listThree]; //true System.out.println[isEqual]; } }Program output.
false trueComparing two ArrayList In Java
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:
Input : ArrayList1 = [1, 2, 3, 4], ArrayList2 = [1, 2, 3, 4] Output: Array List are equal Input : ArrayList1 = [1, 2, 3, 4], ArrayList2 = [4, 2, 3, 1] Output: Array List are not equalSyntax:
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.
Article Tags :
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1. Introduction
In this article, We'll learn how to compare two ArrayLists for checking Objects equality.
ArrayList has an equal[] method that takes one argument type of Object. This equals[] method compares the passed list object with the current list object. If both lists are having same values then it returns true, otherwise false. equals[]
Read more on how to compare two strings lexicographically.
Example programs are shown on equals[], containsAll[] and java 8 Stream API.
At the end of the article you will be good with comparing two lists and find differences between two lists in java
1. Overview
Finding differences between collections of objects of the same data type is a common programming task. As an example, imagine we have a list of students who applied for an exam and another list of students who passed it. The difference between those two lists would give us the students who didn't pass the exam.
In Java, there's no explicit way for finding differences between two lists in the List API, though there are some helper methods that come close.
In this quick tutorial, we'll look at how to find the differences between the two lists. We'll try a few different approaches, including plain Java [with and without Streams] and using third-party libraries such as Guava and the Apache Commons Collections.
How to Compare Two ArrayList in Java
June 12, 2021October 12, 2021 0 Comments compare elements of same arraylist in java, equals, how to compare elements of an arraylist in java 8, how to compare two arraylist in java and find difference, how to compare two arraylist objects in java, how to compare two list in java, how to compare two list of objects in java
In this tutorial, we are going to see how to compare two ArrayList in Java. You can compare two ArrayLists using the equals[] method of the ArrayList class, this method accepts a list object as a parameter, compares it to the current object, if there is a match, it returns TRUE and otherwise, it returns FALSE.
Output:
The two arraylists are equal.- JFrame Exit on Close Java Swing
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