Example:Input: a = {"1","2","3","4","5"} b = {"1","2","3"} Result: 1,2,3Get Common Elements from two Lists:retainAll() method from the Collection interface is used to remove the common elements from two different lists. Show
Find common elements in two ArrayLists in Java
Given two ArrayLists, the task is to print all common elements in both the ArrayLists in Java . Examples: Input: List1 = ["Hii", "Geeks", "for", "Geeks"], List2 = ["Hii", "Geeks", "Gaurav"] Output: [Hii, Geeks, Geeks] Input: List1 = ["a", "b", "c", "d", "e", "f"], List2 = ["b", "d", "e", "h", "g", "c"] Output:[b, c, d, e]
Article Tags : Java Technical Scripter Java - util package Java-Collections Java-List-Programs Technical Scripter 2018 Practice Tags : Java Java-Collections 1. OverviewIn this tutorial, we'll learn how to retrieve the intersection of two Lists. Like many other things,this has become much easier thanks to the introduction ofstreams in Java 8. 1. OverviewFinding 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 List Objects in Java 7 vs. Java 8In this blast from the not-too-distant past, we compare how Java 8's Stream API changed how you can compare List objects.by Arpan Das ·Jun. 01, 18 · Java Zone · TutorialLike (12) Comment Save Tweet 259.66K Views Join the DZone community and get the full member experience. Join For FreeComparing the content of Lists against some condition is a common use case to handle in many business scenarios. This comparison can be broadly classified as:
Now, developing these use cases is very easy in Java 7 with relatively few lines of code. The following is an example where we are comparing two Lists in Java 7 and checking if any element from List 1 exists in List 2. package com.tuturself; import java.util.Arrays; import java.util.List; public class ListCompare { public static void main(String[] args) { List < Integer > aList = Arrays.asList(new Integer[] { 1, 3, 5, 6, 8 }); List < Integer > bList = Arrays.asList(new Integer[] { 10, 89, 8, 9 }); for (Integer i: aList) { if (bList.contains(i)) { System.out.println("Match Found " + i); break; } } } }Now let us develop all the above use cases in Java 8. The Java 8 Stream API provides threemethods allMatch, anyMatch, and noneMatch, which can be applied to a stream object that matches the given Predicate and then returns a boolean value. It is recommended to check the following articles if you are not familiar with the Stream API.
1. Compare two arraylists for equalityJava program to test if two given lists are equal. To test equality –
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<String> listOne = new ArrayList<>(Arrays.asList("a", "b", "c", "d", "f")); ArrayList<String> 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<String> listThree = new ArrayList<>(Arrays.asList("a", "b", "c", "d", "f")); isEqual = listOne.equals(listThree); //true System.out.println(isEqual); } }Program output. false true1. IntroductionIn 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 |