Java passing 2 dimension array to method

Question

public static void main{
    String [][] book = new String[100][6];

    for(int i = 0; i < 1; i++) {
        for(int j = 0; j < 5; j++) {
            book[i][j] = i;
        }
    }

    arrayMethod(book);
}

public static void arrayMethod(String[][] array){
    System.out.println(Arrays.asList(array));
}

arrayMethod method output is [[Ljava.lang.String;@639facbc, [Ljava.lang.String;@8059dbd, [Ljava.lang.String;@28b6e768, [Ljava.lang.String;@1271ba, ....

Problem is that in arrayMethod I can't acces 2 dimension array data, where can be problem?

to compile you have to use book[i][j] =""+ i;

Sergei Chicherin
– Sergei Chicherin

2013-12-02 13:38:16 +00:00
Commented Dec 2, 2013 at 13:38 — Sergei Chicherin
– Sergei Chicherin, Commented Dec 2, 2013 at 13:38
What about the signature of main method ??

Sameer Sawla
– Sameer Sawla

2013-12-02 13:51:27 +00:00
Commented Dec 2, 2013 at 13:51 — Sameer Sawla
– Sameer Sawla, Commented Dec 2, 2013 at 13:51

chrylis -cautiouslyoptimistic- · Accepted Answer · 2013-12-02 13:36:23Z

4

It's doing exactly what you want: you're pretending the (first-level) array is a List (of Array) and then printing the toString() of those, which looks something like [Ljava.lang.String@pointer. You probably want this instead:

System.out.println(Arrays.deepToString(array));

answered Dec 2, 2013 at 13:36

chrylis -cautiouslyoptimistic-

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Comments

Fr0z3n7 · Accepted Answer · 2013-12-02 13:44:36Z

2

as Alya'a Gamal said, if you want to put an int inside an array of String you need to parse it : book[i][j] = Integer.toString(i);. Then if you want to display your array, you need to run thought it, like this for example :

public static void arrayMethod(String[][] array){
        for(int i = 0; i < array.length;i++) {
            for(int j = 0; j < array[i].length;j++)
                System.out.println(array[i][j]); // a stringBuilder would be better than to print inside the loop
        }

    }

answered Dec 2, 2013 at 13:44

Fr0z3n7

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1 Comment

Wizard Over a year ago

Have one problem, passing only 1 (last) array element, all oher elements is null

Mengjun · Accepted Answer · 2013-12-02 13:46:46Z

2

You can use Arrays.toString to print 1-D string array, but you CANNOT use Arrays.toString to print the 2-D array directly.

There are 2 ways for you to print the 2D string array in console.

Way#1 ==>

System.out.println(Arrays.deepToString(array));

Way#2 ==>

 for(String[] arr: array)
 {
        System.out.println(Arrays.toString(arr));
 }

answered Dec 2, 2013 at 13:46

Mengjun

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Comments

Sameer Sawla · Accepted Answer · 2013-12-02 13:59:47Z

I see three issues here :

(1). The signature of the main method looks odd. It would raise a compile issue.

public static void main(String args[])
{
// Your code here
}

(2). In the following code :

for(int i = 0; i < 1; i++) {
  for(int j = 0; j < 5; j++) {
            book[i][j] = i;
        }
    }

book[i][j] =i; // Here you are trying to insert an int in place where a String is required.

This will again lead to a compile time issue.

You can correct it as follows:

 book[i][j] = Integer.toString(i);

(3).

Use the following static method in the Arrays class to print the elements of 2D array on the console.

System.out.println(Arrays.deepToString(array));

Hope this helps.

+1 for isolating the problem.

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