How to initialize an ArrayList in one line

By mkyong | Updated: August 18, 2016

Viewed: 360

Tags: arraylist java

Here’s a few ways to initialize an java.util.ArrayList, see the following full example:

package com.mkyong.examples;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class InitArrayList {

    public static void main(String[] args) {

        //1. Normal way
        List<String> list = new ArrayList<String>();
        list.add("String A");
        list.add("String B");
        list.add("String C");

        System.out.println("List 1......");
        for (String temp : list) {
            System.out.println(temp);
        }

        //2. Anonymous inner class
        List<String> list2 = new ArrayList<String>() {
            {
                add("String A");
                add("String B");
                add("String C");
            }
        };

        System.out.println("List 2......");
        for (String temp : list2) {
            System.out.println(temp);
        }

        //3. One line
        List<String> list3 = Arrays.asList("String A", "String B", "String C");

        System.out.println("List 3......");
        for (String temp : list3) {
            System.out.println(temp);
        }

    }

}

Output

List 1......
String A
String B
String C
List 2......
String A
String B
String C
List 3......
String A
String B
String C