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]
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:
String[] array = new String[] {"John", "Mary", "Bob"};
System.out.println(Arrays.toString(array));
Output:
[John, Mary, Bob]
String[][] deepArray = new String[][] {{"John", "Mary"}, {"Alice", "Bob"}};
System.out.println(Arrays.toString(deepArray));
//output: [[Ljava.lang.String;@106d69c, [Ljava.lang.String;@52e922]
System.out.println(Arrays.deepToString(deepArray));
Output:
[[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 ]
What if we have an array of strings, and want simple output; like:
String[] array = {"John", "Mahta", "Sara"}
, and we want this output without bracket and commas:John Mahta Sara
?@Hengameh: There are several other ways to do this, but my favorite is this one: javahotchocolate.com/notes/java.html#arrays-tostring .
FYI,
Arrays.deepToString()
accepts only anObject []
(or an array of classes that extendObject
, such asInteger
, so it won't work on a primitive array of typeint []
. ButArrays.toString(<int array>)
works fine for primitive arrays.@Hengameh There's a method dedicated to that.
System.out.println(String.join(" ", new String[]{"John", "Mahta", "Sara"}))
will printJohn Mahta Sara
.Don't forget "import java.util.Arrays;"