How to initialize a 2D array of strings in java

Question

I know how to declare the array and I have done so:

String[][] board1 = new String[10][10];

Now I want to make it so that every space is "-" by default (without the quotes of course). I have seen other questions like this but the answers didn't make sense to me. All I can understand is that I would probably need a for loop.

Elliott Frisch · Accepted Answer · 2014-10-14 01:25:07Z

9

The quickest way I can think of is to use Arrays.fill(Object[], Object) like so,

String[][] board1 = new String[10][10];
for (String[] row : board1) {
    Arrays.fill(row, "-");
}
System.out.println(Arrays.deepToString(board1));

This is using a For-Each to iterate the String[](s) of board1 and fill them with a "-". It then uses Arrays.deepToString(Object[]) to print it.

answered Oct 14, 2014 at 1:25

Elliott Frisch

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MadProgrammer · Accepted Answer · 2014-10-14 01:48:28Z

6

You could do ...

String[][] board1 = new String[][] {
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
    {"-", "-", "-", "-", "-", "-", "-", "-", "-", "-"},
};

or

String[][] board1 = new String[10][10];
for (int outter = 0; outter < board1.length; outter++) {
    String[] row = new String[board1[outter].length];
    for (int inner = 0; inner < row.length; inner++) {
        row[inner] = "-";
    }
    board1[outter] = row;
}

or

String[][] board1 = new String[10][10];
for (int outter = 0; outter < board1.length; outter++) {
    for (int inner = 0; inner < board1[outter].length; inner++) {
        board1[outter][inner] = "-";
    }
}

edited Oct 14, 2014 at 1:48

answered Oct 14, 2014 at 1:25

MadProgrammer

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3 Comments

Hearen Over a year ago

Actually I really wonder why the first method cannot specify the size. Really CANNOT, why? new long[2][2] { {1, 1}, {1, 0}}; will fail.

MadProgrammer Over a year ago

@Hearen Really never though out it, but I think the language is just basically saying you either tell me up front or you show me

Hearen Over a year ago

It kind of makes sense but still is weird if both provided, it will turn out to be an error.

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