Source code demonstration for article at https://kodemate.com/convert-array-to-list-and-vice-versa-in-java/

ConversionTest.java

import org.junit.Assert;
import org.junit.Test;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import java.util.stream.Collectors;

import static org.hamcrest.core.Is.is;

/**
 * KodeMate.com - Learn coding with crazy passion
 *
 * @author   Pete Houston <contact@petehouston.com>
 * @article  Convert Array to List and vice versa
 * @url      https://kodemate.com/convert-array-to-list-and-vice-versa-in-java/
 */

public class ConversionTest {

    private final Integer[] BASE_ARRAY = new Integer[] {1, 10, 99};
    private final List<Integer> RESULT_LIST = new ArrayList<Integer>() {{
        add(1);
        add(10);
        add(99);
    }};

    private final List<Integer> BASE_LIST = new ArrayList<Integer>() {{
        add(14);
        add(42);
        add(2018);
    }};
    private final Integer[] RESULT_ARRAY = new Integer[] {14, 42, 2018};


    @Test
    public void Array2List_Using_Java_Core() {
        // 1. loop / iteration
        List<Integer> list1 = new ArrayList<>();
        for(Integer i: BASE_ARRAY) {
            list1.add(i);
        }

        Assert.assertThat(list1, is(RESULT_LIST));

        // 2. Collection.addAll() method
        List<Integer> list2 = new ArrayList<>();
        Collections.addAll(list2, BASE_ARRAY);

        Assert.assertThat(list2, is(RESULT_LIST));

        // 3. Arrays.asList() method
        List<Integer> list3 = Arrays.asList(BASE_ARRAY);

        Assert.assertThat(list3, is(RESULT_LIST));

        // 4. Using Stream API in Java 8
        List<Integer> list4 = Arrays.stream(BASE_ARRAY).collect(Collectors.toList());

        Assert.assertThat(list4, is(RESULT_LIST));
    }

    @Test
    public void List2Array_Using_Java_Core() {
        // 1. loop / iteration
        Integer[] array1 = new Integer[BASE_LIST.size()];
        for(int i = 0; i < BASE_LIST.size(); i++) {
            array1[i] = BASE_LIST.get(i);
        }
        
        Assert.assertArrayEquals(RESULT_ARRAY, array1);
        
                // 2. List.toArray() method
        Integer[] array2 = BASE_LIST.toArray(new Integer[BASE_LIST.size()]);
        
        Assert.assertArrayEquals(RESULT_ARRAY, array2);
        
                // 3. even better List.toArray()
        Integer[] array3 = BASE_LIST.toArray(new Integer[0]);
        
        Assert.assertArrayEquals(RESULT_ARRAY, array3);
    }
}