We have many ways to initialize ArrayList in java.
ArrayList can be initialized in one line, Using constructors, Using Arrays.
1. Initialize ArrayList using Constructors
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package com.kscodes.sampleproject; import java.util.ArrayList; import java.util.List; public class ArrayListInitalize { public static void main(String[] args) { List<String> arrList = new ArrayList<>(); arrList.add("Java"); arrList.add("JSP"); arrList.add("JavaScript"); arrList.add("JQuery"); System.out.println(arrList.toString()); } } |
2. Initialize ArrayList in One line using Arrays.asList()
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package com.kscodes.sampleproject; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class ArrayListInitalize { public static void main(String[] args) { List<String> arrList = new ArrayList<>(Arrays.asList("Java","JSP","JavaScript","JQuery")); System.out.println(arrList.toString()); } } |
3. Initialize ArrayList using Collections (Another List)
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package com.kscodes.sampleproject; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class ArrayListInitalize { public static void main(String[] args) { List<String> arrList1 = new ArrayList<>(Arrays.asList("Java","JSP","JavaScript","JQuery")); List<String> arrList2 = new ArrayList<>(arrList1); System.out.println(arrList2.toString()); } } |
4. Initialize ArrayList using InnerClass
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package com.kscodes.sampleproject; import java.util.ArrayList; import java.util.List; public class ArrayListInitalize { public static void main(String[] args) { List<String> arrList = new ArrayList<String>(){{ add("Java"); add("JSP"); add("JavaScript"); add("JQuery"); } }; System.out.println(arrList.toString()); } } |