In this article, we will show you a few ways to print a Java Array.

1. Arrays.toString

This is the simplest way to print an Array – Arrays.toString (since JDK 1.5)

package com.mkyong.utils.print;
import java.util.Arrays;
public class PrintArray {
    public static void main(String[] args) {
		// array
        String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
        System.out.println(Arrays.toString(arrayStr));
        // Output : [Java, Node, Python, Ruby]
		int[] arrayInt = {1, 3, 5, 7, 9};
        System.out.println(Arrays.toString(arrayInt));
        // Output : [1, 3, 5, 7, 9]
        // 2d array, need Arrays.deepToString
        String[][] deepArrayStr = new String[][]{{"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
        System.out.println(Arrays.toString(deepArrayStr));
        // Output : [[Ljava.lang.String;@23fc625e, [Ljava.lang.String;@3f99bd52]
        System.out.println(Arrays.deepToString(deepArrayStr));
        // Output : [[mkyong1, mkyong2], [mkyong3, mkyong4]
        int[][] deepArrayInt = new int[][]{{1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
        System.out.println(Arrays.toString(deepArrayInt));
        // Output : [[I@3a71f4dd, [I@7adf9f5f]
        System.out.println(Arrays.deepToString(deepArrayInt));
        // Output : [[1, 3, 5, 7, 9], [2, 4, 6, 8, 10]]

Output

[Java, Node, Python, Ruby]
[1, 3, 5, 7, 9]
[[Ljava.lang.String;@23fc625e, [Ljava.lang.String;@3f99bd52]
[[mkyong1, mkyong2], [mkyong3, mkyong4]]
[[I@3a71f4dd, [I@7adf9f5f]
[[1, 3, 5, 7, 9], [2, 4, 6, 8, 10]]

2. JDK 8 Stream

In JDK 8, we can convert it to Stream and print it.

package com.mkyong.utils.print;
import java.util.Arrays;
public class PrintArray {
    public static void main(String[] args) {
        // array
        String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
        Arrays.stream(arrayStr).forEach(System.out::println);
        int[] arrayInt = {1, 3, 5, 7, 9};
        Arrays.stream(arrayInt).forEach(System.out::println);
        //2d array
        String[][] deepArrayStr = new String[][]{{"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
        Arrays.stream(deepArrayStr).flatMap(x -> Arrays.stream(x)).forEach(System.out::println);
        int[][] deepArrayInt = new int[][]{{1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
        Arrays.stream(deepArrayInt).flatMapToInt(x -> Arrays.stream(x)).forEach(System.out::println);

Output

Java
Node
Python
Ruby
mkyong1
mkyong2
mkyong3
mkyong4
10

3. Json Anything

This is my favor method, use Jackson2 library to print anything in a JSON formatted string.

package com.mkyong.utils.print;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
public class PrintUtils {
    private static final ObjectMapper om = new ObjectMapper();
	public static void print(Object object) {
		String result;
		try {
			result = om.writerWithDefaultPrettyPrinter().writeValueAsString(object);
            System.out.println(result);
        } catch (JsonProcessingException e) {
			e.printStackTrace();

package com.mkyong.utils.print;
public class PrintArray {
    public static void main(String[] args) {
		//array
        String[] arrayStr = new String[]{"Java", "Node", "Python", "Ruby"};
        PrintUtils.print(arrayStr);
        int[] arrayInt = {1, 3, 5, 7, 9};
        PrintUtils.print(arrayInt);
		//2d array
        String[][] deepArrayStr = new String[][]{{"mkyong1", "mkyong2"}, {"mkyong3", "mkyong4"}};
        PrintUtils.print(deepArrayStr);
        int[][] deepArrayInt = new int[][]{{1, 3, 5, 7, 9}, {2, 4, 6, 8, 10}};
        PrintUtils.print(deepArrayInt);

Output

[ "Java", "Node", "Python", "Ruby" ]
[ 1, 3, 5, 7, 9 ]
[ [ "mkyong1", "mkyong2" ], [ "mkyong3", "mkyong4" ] ]
[ [ 1, 3, 5, 7, 9 ], [ 2, 4, 6, 8, 10 ] ]

References

1. Steam Javasoc
2. Arrays JavaDoc
3. Jackson 2 convert Java object to from JSON
4. Jackson 2 official site