- ArrayList class is resizable array implementation of the List interface.
- ArrayList maintains the insertion order of element or string objects.
- ArrayList allows the duplicate elements & we can randomly access elements by index.
- ArrayList is not thread safe.
- If multiple threads access an ArrayList instance concurrently, then arraylist must be synchronized externally.
- Given an arraylist collection, we would demonstrate the following operations on arraylist.
- Remove
- Add
- Retain
- Sort
- Iterate
- Get
- Contains And
- Clear
1. Class Hierarchy of ArrayList Collection:
![](https://www.makeinjava.com/wp-content/uploads/2016/05/ArrayList-Collection-in-java-class-hierarchy.jpg)
2. Add,sort,iterate,get,contains,clear methods of arraylist (java /example)
package org.learn.collection.list.arrayList; import java.util.ArrayList; import java.util.Collections; import java.util.ListIterator; public class DemoArrayList { public static void main(String[] args) { ArrayList<String> arrayList = new ArrayList<>(); arrayList.add( "archery" ); arrayList.add( "badminton" ); arrayList.add( "canoe" ); arrayList.add( "boxing" ); arrayList.add( "diving" ); arrayList.add( "beach volleyball" ); System.out.println( "1. Demo of remove methods of ArrayList: " ); demoRemoveMethod(arrayList); System.out.println( "\n2. Demo of add methods of ArrayList: " ); demoAddMethod(arrayList); System.out.println( "\n3. Demo of retain method of ArrayList: " ); demoRetainAll(arrayList); System.out.println( "\n4. Sort elements of arrayList collection: " ); demoSortMethod(arrayList); System.out.println( "\n5. Iterate through arrayList collection: " ); demoIterateMethod(arrayList); System.out.println( "\n6. Demo of get method of arraylist collection: " ); System.out.println( "Element at index 0: " + arrayList.get( 0 )); System.out.println( "Element at index 2: " + arrayList.get( 2 )); System.out.println( "\n7. Demo of contains method of arraylist collection: " ); System.out.println( "Check arraylist contains diving: " + arrayList.contains( "diving" )); System.out.println( "Check arraylist contains soccer: " + arrayList.contains( "archery" )); System.out.println( "\n8.Demo of clear method of arraylist collection: " ); arrayList.clear(); System.out.println( "Clear arrayList: " + arrayList); } private static void demoRemoveMethod(ArrayList<String> arrayList) { // [archery, badminton, canoe, boxing, diving, beach volleyball] System.out.println( "Orignal ArrayList:" + arrayList); // Remove element by index arrayList.remove( 0 ); // [badminton, canoe, boxing, diving, beach volleyball] System.out.println( "Removed element at 0 index: " + arrayList); // Remove element after comparing and remove it arrayList.remove( "boxing" ); // [badminton, canoe, diving, beach volleyball] System.out.println( "Removed boxing from arrayList: " + arrayList); ArrayList<String> removeElementsList = new ArrayList<>(); removeElementsList.add( "canoe" ); removeElementsList.add( "diving" ); removeElementsList.add( "beach volleyball" ); // Remove element by supplying another collection arrayList.removeAll(removeElementsList); // [badminton] System.out.println( "Removed collection containing canoe and diving: " + arrayList); } private static void demoAddMethod(ArrayList<String> arrayList) { //[badminton] System.out.println( "Orignal ArrayList:" + arrayList); arrayList.add( 0 , "archery" ); arrayList.add( 2 , "canoe" ); // [archery, badminton, canoe] System.out.println( "Added element at 0,2 index: " + arrayList); arrayList.add( "diving" ); // [archery, badminton, canoe, diving] System.out.println( "Added element in list: " + arrayList); ArrayList<String> addElementsList = new ArrayList<>(); addElementsList.add( "squash" ); addElementsList.add( "bowling" ); // It will add elements to last of list arrayList.addAll(addElementsList); // [archery, badminton, canoe, diving, squash, bowling] System.out.println( "Added another list : " + arrayList); ArrayList<String> anotherList = new ArrayList<>(); anotherList.add( "golf" ); anotherList.add( "judo" ); // It will add elements to last of list arrayList.addAll( 1 , anotherList); //[archery, golf, judo, badminton, canoe, diving, squash, bowling] System.out.println( "Added another list at index 1 : " + arrayList); } private static void demoRetainAll(ArrayList<String> arrayList) { //[archery, golf, judo, badminton, canoe, diving, squash, bowling] System.out.println( "Orignal ArrayList:" + arrayList); ArrayList<String> retainSportsList = new ArrayList<>(); retainSportsList.add( "soccer" ); retainSportsList.add( "judo" ); retainSportsList.add( "archery" ); retainSportsList.add( "badminton" ); arrayList.retainAll(retainSportsList); // [archery, judo, badminton] System.out.println( "Retaining elements soccer, judo and archery list: " + arrayList); } private static void demoSortMethod(ArrayList<String> arrayList) { // [archery, judo, badminton] System.out.println( "Orignal ArrayList:" + arrayList); Collections.sort(arrayList); //[archery, badminton, judo] System.out.println( "Sort ascending order: " + arrayList); Collections.sort(arrayList, Collections.reverseOrder()); //[judo, badminton, archery] System.out.println( "Sort desending order: " + arrayList); } private static void demoIterateMethod(ArrayList<String> arrayList) { System.out.println( "Iterating using forEachRemaining:" ); // Output of for loop: // judo badminton archery arrayList.forEach(element -> System.out.printf( "%s " , element)); System.out.println( "\nIterating arrayList using foreach loop:" ); // Output of for loop: // judo badminton archery for (String element : arrayList) { System.out.printf( "%s " , element); } System.out.println( "\nIterating arrayList using iterator:" ); ListIterator<String> listIterator = arrayList.listIterator(); // Output of while loop: // judo badminton archery while (listIterator.hasNext()) { System.out.printf( "%s " , listIterator.next()); } System.out.println( "" ); } } |
3. Add,sort,iterate,get,contains,clear methods of arraylist (java /example)
1. Demo of remove methods of ArrayList: Orignal ArrayList:[archery, badminton, canoe, boxing, diving, beach volleyball] Removed element at 0 index: [badminton, canoe, boxing, diving, beach volleyball] Removed boxing from arrayList: [badminton, canoe, diving, beach volleyball] Removed collection containing canoe and diving: [badminton] 2. Demo of add methods of ArrayList: Orignal ArrayList:[badminton] Added element at 0,2 index: [archery, badminton, canoe] Added element in list: [archery, badminton, canoe, diving] Added another list : [archery, badminton, canoe, diving, squash, bowling] Added another list at index 1 : [archery, golf, judo, badminton, canoe, diving, squash, bowling] 3. Demo of retain method of ArrayList: Orignal ArrayList:[archery, golf, judo, badminton, canoe, diving, squash, bowling] Retaining elements soccer, judo and archery list: [archery, judo, badminton] 4. Sort elements of arrayList of ArrayList: Orignal ArrayList:[archery, judo, badminton] Sort ascending order: [archery, badminton, judo] Sort desending order: [judo, badminton, archery] 5. Iterate through arrayList collection: Iterating using forEachRemaining: judo badminton archery Iterating arrayList using foreach loop: judo badminton archery Iterating arrayList using iterator: judo badminton archery 6. Demo of get method of arraylist collection: Element at index 0: judo Element at index 2: archery 7. Demo of contains method of arraylist collection: Check arraylist contains diving: false Check arraylist contains soccer: true 8.Demo of clear method of arraylist collection: Clear arrayList: [] |