ArrayList to Array Conversion in Java : toArray() Methods

Following methods can be used for converting ArrayList to Array:

Method 1: Using Object[] toArray() method

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

/**
 * ArrayListToArray class
 *
 * @author libin
 * @date 2019/1/25 15:43
 */
public class ArrayListToArray {
    public static void main(String[] args) {
        List<Integer> al = new ArrayList<Integer>();
        al.add(10);
        al.add(20);
        al.add(30);
        al.add(40);
        Object[] objects = al.toArray();
        for (Object obj : objects) {
            System.out.print(obj + " ");
        }
    }
}

Method 2: Using T[] toArray(T[] a)

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

/**
 * ArrayListToArray class
 *
 * @author libin
 * @date 2019/1/25 15:43
 */
public class ArrayListToArray {
    public static void main(String[] args) {
        List<Integer> al = new ArrayList<Integer>();
        al.add(10);
        al.add(20);
        al.add(30);
        al.add(40);
        Integer[] arr = new Integer[al.size()];
        arr = al.toArray(arr);
        for (Integer x : arr) {
            System.out.print(x + " ");
        }
    }
}

Method 3: Manual method to covert ArrayList using get() method

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

/**
 * ArrayListToArray class
 *
 * @author libin
 * @date 2019/1/25 15:43
 */
public class ArrayListToArray {
    public static void main(String[] args) {
        List<Integer> al = new ArrayList<Integer>();
        al.add(10);
        al.add(20);
        al.add(30);
        al.add(40);
        Integer[] arr = new Integer[al.size()];
        for (int i = 0; i < al.size(); i++) {
            arr[i] = al.get(i);
        }
        for (Integer x : arr) {
            System.out.print(x + " ");
        }
    }
}

参考链接

• https://www.geeksforgeeks.org/arraylist-array-conversion-java-toarray-methods/