Java Convert Array to ArrayList
摘要: In Java, we can use new ArrayList<>(Arrays.asList(array)) to convert an Array into an ArrayList
In Java, we can use new ArrayList<>(Arrays.asList(array)) to convert an Array into an ArrayList
ArrayExample1.java
package com.mkyong;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ArrayExample1 {
public static void main(String[] args) {
String[] str = {"A", "B", "C"};
List<String> list = new ArrayList<>(Arrays.asList(str));
list.add("D");
list.forEach(x -> System.out.println(x));
Output
The Arrays.asList returns a fixed or unmodifiable list, if we modify the list, UnsupportedOperationException will be thrown.
List<String> list = Arrays.asList(str); // unmodifiable list
list.add("D"); // java.lang.UnsupportedOperationException
List<String> list2 = new ArrayList<>(Arrays.asList(str)); // modifiable list
list2.add("D"); // ok
1. Java 8 Stream
ArrayExample2.java
package com.mkyong;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class ArrayExample2 {
public static void main(String[] args) {
String[] str = {"A", "B", "C"};
ArrayList<String> list1 = Stream.of(str).collect(Collectors.toCollection(ArrayList::new));
list1.add("D");
list1.forEach(x -> System.out.println(x));
List<String> list2 = Stream.of(str).collect(Collectors.toList());
list2.add("D");
list2.forEach(x -> System.out.println(x));
Output
2. Java 9 – List.of()
P.S List.of returns fixed or unmodifiable list
ArrayExample3.java
package com.mkyong;
import java.util.ArrayList;
import java.util.List;
public class ArrayExample3 {
public static void main(String[] args) {
String[] str = {"A", "B", "C"};
// Java 9
List<String> list = new ArrayList<>(List.of("A", "B", "C"));
list.add("D");
list.forEach(x -> System.out.println(x));
Output
