What's the simplest way to print a Java array?
arrays, java, printing, tostring
Solution
Since Java 5 you can use `Arrays.toString(arr)` or `Arrays.deepToString(arr)` for arrays within arrays. Note that the `Object[]` version calls `.toString()` on each object in the array. The output is even decorated in the exact way you're asking.
Examples:
Simple Array:
String[] array = new String[] {"John", "Mary", "Bob"};
System.out.println(Arrays.toString(array));
Output:
[John, Mary, Bob]
Nested Array:
String[][] deepArray = new String[][] {{"John", "Mary"}, {"Alice", "Bob"}};
// Gives undesired output:
System.out.println(Arrays.toString(deepArray));
// Gives the desired output:
System.out.println(Arrays.deepToString(deepArray));
Output:
[[Ljava.lang.String;@106d69c, [Ljava.lang.String;@52e922]
[[John, Mary], [Alice, Bob]]
`double` Array:
double[] doubleArray = { 7.0, 9.0, 5.0, 1.0, 3.0 };
System.out.println(Arrays.toString(doubleArray));
Output:
[7.0, 9.0, 5.0, 1.0, 3.0 ]
`int` Array:
int[] intArray = { 7, 9, 5, 1, 3 };
System.out.println(Arrays.toString(intArray));
Output:
[7, 9, 5, 1, 3 ]
Problem
In Java, arrays don't override `toString()`, so if you try to print one directly, you get the `className` + '@' + the hex of the `hashCode` of the array, as defined by `Object.toString()`: ``` int[] intArray = new int[] {1, 2, 3, 4, 5}; System.out.println(intArray); // Prints something like '[I@3343c8b3' ``` But usually, we'd actually want something more like `[1, 2, 3, 4, 5]`. What's the simplest way of doing that? Here are some example inputs and outputs: ``` // Array of primitives: int[] intArray = new int[] {1, 2, 3, 4, 5}; // Output: [1, 2, 3, 4, 5] // Array of object references: String[] strArray = new String[] {"John", "Mary", "Bob"}; // Output: [John, Mary, Bob] ```