Iterates through the array x using a for loop. Returns the elements of x as a String where each element is separated by a single space

Question

public static String toStringFor(){

    int[] x={3, 45, 17, 2, -1, 44, 9, 23, 67, 2, -6, -23, -100, 12, 5, 1212};

    String array = x.toString();

    return array;
}

I keep getting

[I@62aba879

Possible duplicate of [A quick and easy way to join array elements with a separator (the opposite of split) in Java](http://stackoverflow.com/questions/1978933/a-quick-and-easy-way-to-join-array-elements-with-a-separator-the-opposite-of-sp) — Kevin J. Chase, Mar 14 '17 at 01:05

score 2 · Answer 1 · edited May 23 '17 at 11:54

What you are seeing is the hashcode of the array instance. You can't simply use toString() on an array and expect to give you a nice result. In fact, each object has its own toString() method that can be implemented in various ways. This is how the implementation of toString() on an array looks like:

public String toString() {
    return getClass().getName() + "@" + Integer.toHexString(hashCode());
}

You will have to iterate through the elements and create the final string yourself. Here's a way to do it in Java 8:

int[] x={3, 45, 17, 2, -1, 44, 9, 23, 67, 2, -6, -23, -100, 12, 5, 1212};

String result = Arrays.stream(x)
        .mapToObj(String::valueOf)
        .collect(Collectors.joining(" "));
System.out.println("result = " + result);

This creates a stream of values from your array and collects them into a String separated with space.

Another version with a for loop:

StringJoiner sj = new StringJoiner(" ");
for (int i : x) {
    sj.add(String.valueOf(i));
}
System.out.println("result =" + sj.toString());

You can also iterate the array using:

for (int i = 0; i < x.length; i++) {
...
}

As seen in this answer.

@SkrewEverything Then my day just got even better ;) – MartinTeeVarga Mar 14 '17 at 00:24 — MartinTeeVarga, Mar 14 '17 at 00:24

Alberto Pérez · Answer 2 · 2017-03-14T00:33:24.837

1

You should use a for and StringJoiner(credits to @sm4) to help with that purpose

public static String toStringFor(){

    int[] x={3, 45, 17, 2, -1, 44, 9, 23, 67, 2, -6, -23, -100, 12, 5, 1212};


    StringJoiner sj=new StringJoiner(" ");

    for (int i = 0; i < x.length; i++) {
        sj.add(String.valueOf(x[i]));
    }

    return sj.toString();
}

edited Mar 14 '17 at 00:33

answered Mar 14 '17 at 00:14

Alberto Pérez

52
7

But he needs a string which is separated by a space. We should iterate through all elements to construct the string. – SkrewEverything Mar 14 '17 at 00:18
In that case, he would use a for to go trought every element on array and concat it on a new String or StringBuilder – Alberto Pérez Mar 14 '17 at 00:19
I said so that you will update your answer and you are literally saying what I said. – SkrewEverything Mar 14 '17 at 00:22
1

While you can use StringBuilder, I would not recommend it. First, you are using it kind of wrong, since you are also using a String concatenation. The compiler will probably deal with it just fine, but you are creating some extra String instances when doing sb.append("a" + "b"). Second, you will have a trailing space in the result. Look at my answer and consider using StringJoiner (either directly or through a collector on a stream). – MartinTeeVarga Mar 14 '17 at 00:29
@sm4 You're right, i'll edit my answer. Didn't know about StringJoiner, each day gets betters since I'm here on StackOverflow haha, thanks guys. Always learning i guess ^^ – Alberto Pérez Mar 14 '17 at 00:32

score 0 · Answer 3 · answered Mar 14 '17 at 00:16

toString returns a string holding some abbreviation characters followed by the hexadecimal representation of a hash, unless overridden. Arrays don't override this, so you got the toString of the object that the array is.

You need to write custom code to accomplish your goal. Perhaps you could loop through the array, appending the String representation of each array element to a StringBuilder along with some characters for formatting, and output the toString of the resulting StringBuilder from your method that performs that task.

@Alberto Pérez offers the more utilitarian answer. This answer is more pedagogical. — Lew Bloch, Mar 14 '17 at 00:17

mike · Answer 4 · 2017-03-14T00:36:49.760

The problem here is that you're calling toString() on the array object - not on the elements within the array.

Use Arrays.toString(int[] a) instead.

In order to generate a string representation of the array, which is separated by space, it helps, if you handle the first array item independently and then add all further elements prefixed by a space.

    int[] x = {1, 2, 3, 4};

    int i = 0;
    String arr = String.valueOf(x[i++]);
    for (; i < x.length; i++)
        arr += " " + x[i];

Doing so leaves no trailing space at the end of the string.

Iterates through the array x using a for loop. Returns the elements of x as a String where each element is separated by a single space

4 Answers4