How to bring together 2 ArrayList inward Java - Example

You tin dismiss purpose the addAll() method from java.util.Collection interface to bring together 2 ArrayLists inwards Java. Since ArrayList implements List interface which genuinely extends the Collection interface, this method is available to all List implementation including ArrayList e.g. Vector, LinkedList. The Collection.addAll(Collection src) method takes a collection in addition to adds all elements from it to the collection which calls this method e.g. target.addAll(source). After this call, the target volition receive got all elements from both root in addition to target ArrayList, which is similar joining 2 ArrayList inwards Java. The mo ArrayList volition rest equally it is but the commencement ArrayList on which you lot receive got added elements volition receive got to a greater extent than elements. Its size volition hold upward equal to the amount of the size of commencement in addition to mo ArrayList.

You should remember, that amongst Generics inwards house you lot cannot bring together 2 unlike types of ArrayList e.g. you lot cannot bring together an Integer ArrayList to String ArrayList or vice-versa. If you lot desire to do a heterogeneous ArrayList, thence you lot should do 2 ArrayList of objects in addition to bring together them together equally shown below:

List<Object> list1 = new ArrayList<Object>(); List<Object> list2 = new ArrayList<Object>();  list1.addAll(list2); // straightaway list1 has chemical factor of both listing 1 in addition to listing 2

This ArrayList tin dismiss comprise whatever type of object e.g. Integer, String, Float, in addition to Double. You tin dismiss likewise read Big Java: Early Objects fifth Edition past times Cay S. Horstmann, a comprehensive guide of Java amongst lots of do questions, quizzes, in addition to diagrams.

Java Program to bring together ArrayList - ArrayList.addAll() Example

Here is a uncomplicated Java programme to demonstrate how to purpose addAll() method of Collection interface to bring together elements of 2 array listing inwards Java. In this program, nosotros receive got 2 ArrayList objects, commencement contains some U.K. based banks e.g. Barclays, Standard Chartered, in addition to HSBC, spell the mo listing contains some the States based banks e.g. Citigroup, Chase, Wells Fargo, in addition to Bank of America. We finally do an ArrayList of global banks past times joining the States in addition to U.K. based depository fiscal establishment together using addAll() method.

The inwards a higher house event is a genuinely proficient scenario of when you lot should bring together ArrayList or whatever other type of List implementation e.g. to do a large listing from 2 smaller lists. If you lot desire to acquire to a greater extent than almost ArrayList degree in addition to its usages inwards Java application, see Big Java: Early Objects past times Cay S. Horstmann , ane of the most comprehensive guides of Java programming language.

interface to bring together 2 ArrayLists inwards Java How to bring together 2 ArrayList inwards Java - Example

Joining ArrayList inwards Java using Collection.addAll()

import java.util.ArrayList; import java.util.List;  /*  * Java Program to bring together 2 ArrayLists into ane   */  public class ArrayListJoiner {    public static void main(String[] args) {      // commencement ArrayList     List<String> UKBasedBanks = new ArrayList<>();     UKBasedBanks.add("Standard Charated");     UKBasedBanks.add("HSBC");     UKBasedBanks.add("Barclays");      // mo ArrayList     List<String> USABanks = new ArrayList<>();     USABanks.add("Citibank");     USABanks.add("Chase");     USABanks.add("Bank of America");     USABanks.add("Wells Fargo");      System.out.println("first arraylist earlier joining : ");     System.out.println(UKBasedBanks);     System.out.println("second arraylist earlier joining : ");     System.out.println(USABanks);      // Joining 2 ArrayList     // adding all elements of USABanks listing to     // UKBasedBanks     UKBasedBanks.addAll(USABanks);      System.out.println("first arraylist later on joining : ");     System.out.println(UKBasedBanks);     System.out.println("second arraylist later on joining : ");     System.out.println(USABanks);    }  }  Output first ArrayList earlier joining :  [Standard Charted, HSBC, Barclays] mo ArrayList earlier joining :  [Citibank, Chase, Bank of America, Wells Fargo] first ArrayList later on joining :  [Standard Charted, HSBC, Barclays, Citibank, Chase, Bank of America, Wells Fargo] mo ArrayList later on joining :  [Citibank, Chase, Bank of America, Wells Fargo]

That's all about how to bring together 2 array lists inwards Java. You tin dismiss purpose this technique to bring together non solely lists but likewise whatever collection because addAll() method is defined on the Collection interface it's available to list, set, in addition to queue. Just retrieve that the root ArrayList volition rest intact but target ArrayList volition hold upward modified to include elements from root ArrayList.

Related Java ArrayList Tutorials for Programmers

How to traverse an ArrayList inwards Java? (example)
How to form an ArrayList inwards Java? (example)
How to opposite an ArrayList inwards Java? (example)
How to synchronize an ArrayList inwards Java? (example)
How to take away objects from ArrayList inwards Java? (solution)
How to take away duplicates from ArrayList inwards Java? (solution)
How to brand an ArrayList read-only inwards Java? (solution)
How to acquire the commencement in addition to in conclusion chemical factor of ArrayList inwards Java? (example)
How to do in addition to initialize an ArrayList inwards the same line? (answer)