Java With Us

How to Print an Array in Java

Updated on 2026-04-21 Reviewed by the Java With Us editorial team

Use Arrays.toString(arr) from java.util.Arrays to print an array in Java. Direct System.out.println(arr) prints an internal identifier like [I@1540e19d, which is almost never what you want.

Why println(arr) doesn't work

int[] nums = {1, 2, 3};
System.out.println(nums);  // [I@1540e19d  ← useless!

Arrays in Java do not override toString(). The default implementation from Object prints the type identifier ([I = int array) and the hash code in hex.

Arrays.toString() — 1D arrays

import java.util.Arrays;

int[]    ints    = {1, 2, 3};
double[] doubles = {1.1, 2.2, 3.3};
String[] strings = {"Java", "Python", "Go"};

System.out.println(Arrays.toString(ints));    // [1, 2, 3]
System.out.println(Arrays.toString(doubles)); // [1.1, 2.2, 3.3]
System.out.println(Arrays.toString(strings)); // [Java, Python, Go]

Arrays.deepToString() — 2D and multi-dimensional arrays

int[][] matrix = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
System.out.println(Arrays.toString(matrix));     // [[I@..., [I@..., ...] — wrong
System.out.println(Arrays.deepToString(matrix)); // [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

Loop-based printing

int[] nums = {10, 20, 30};

// Simple loop:
for (int n : nums) {
    System.out.print(n + " ");
}
System.out.println(); // Output: 10 20 30

// With index:
for (int i = 0; i < nums.length; i++) {
    System.out.printf("[%d]=%d%n", i, nums[i]);
}

Stream-based printing

int[] nums = {1, 2, 3};
Arrays.stream(nums).forEach(System.out::println);

// Join with delimiter:
String joined = Arrays.stream(nums)
    .mapToObj(Integer::toString)
    .collect(Collectors.joining(", "));
System.out.println(joined); // 1, 2, 3

Printing a List vs an array

List<Integer> list = List.of(1, 2, 3);
System.out.println(list);  // [1, 2, 3] — Lists DO override toString()

int[] array = {1, 2, 3};
System.out.println(array); // [I@... — arrays don't

Lists (and all standard collections) implement toString() correctly; arrays do not. This asymmetry trips up beginners, which is why the Arrays utility class exists.

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