Replace elements in a print statement

So i got this String 2Dimensional array that prints me out a playGround :

private final int rowX = 10;
private final int colY = 10;
private final String[][] playGroundArray = new String[rowX][colY];

Then i added with a loop to 10 random positions in my playGroundArray, an char array.

mines[0] = "*";
for (int i = 0; i < numberOfMines; i++) {
            getPlayGroundArray()[random.nextInt(playGroundArray.length - 2) + 1][random.nextInt(playGroundArray.length - 2) + 1] = Arrays.deepToString(mines);
        }

so that all works fine.

Now i print it out.
I get this:

[[ , 0, 1, 2, 3, 4, 5, 6, 7,  ], [0, [*], +, [*], +, +, +, +, [*],  ], [1, +, +, +, +, +, +, +, +,  ], [2, +, +, +, [*], +, +, +, [*],  ], [3, +, +, +, [*], +, +, +, +,  ], [4, +, [*], +, +, +, +, +, +,  ], [5, +, [*], +, +, +, +, +, +,  ], [6, +, +, +, +, +, +, +, +,  ], [7, +, +, +, +, +, +, +, +,  ], [ ,  ,  ,  ,  ,  ,  ,  ,  ,  ]]

I try now with the .replace method to build my playGround so it looks like a playGround:

System.out.println(Arrays.deepToString(playGround.getPlayGroundArray())
                .replace("[[", " ")
                .replace("]]", " \n")
                .replace("], [", " \n")
                .replace("]", " ")
                .replace(",", " ")
                .replace("[", " "));

Not really that what i want

    0  1  2  3  4  5  6  7    
0  +  +  +  +  +   * 
*   +    
1  +   *   +  +  +  +  +  +    
2   *   +  +  +  +  +  +  +    
3  +   *   +  +  +  +  +  +    
4  +   *   +  +  +  +   *   +    
5  +  +  +  +  +  +  +   *     
6  +  +  +  +  +  +  +  +    
7  +  +   *   +  +  +  +  +

So the result should look like that

   0  1  2  3  4  5  6  7    
0  +  *  *  +  +  +  +  +    
1  +  +  +  +  *  +  +  +    
2  +  +  *  +  +  +  +  *     
3  *  +  +  +  +  +  +  +    
4  +  +  *  +  +  *  *  +    
5  +  +  +  +  +  +  +  +    
6  +  +  +  +  +  +  *  +    
7  +  +  +  +  +  +  +  +    

The closest i came was with the code above.
Is there maybe an other solution, cause i tried many ways, but the array braces they are the same, so u cant replace the char arrays braces without changing the braces from the String array as well.
After every 10th element it should make a new line.

Thanks for your help

You should not be using strings to represent a playground - it would be much easier to use booleans, and to not include the coordinates in the enumeration itself:

import java.util.*;
public class Playground {
private boolean mines[][];
private int rows;
private int cols;
public Playground(int rows, int cols, int mineCount) {
this.rows = rows; this.cols = cols;
mines = new boolean[rows][cols];
Random rng = new Random();
while (mineCount > 0) {        
int r = rng.nextInt(rows);
int c = rng.nextInt(cols);
if ( ! hasMine(r, c)) {     // retries placement if mine already there
mines[r][c] = true;
mineCount --;
}
}
}
boolean hasMine(int row, int col) { 
return mines[row][col]; 
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder("   "); // starts with 3 spaces
for (int c=0; c<cols; c++) {
sb.append(String.format("%3d", c));      // left-pads a number with spaces
}
for (int r=0; r<rows; r++) {
sb.append(String.format("\n%3d", r));
for (int c=0; c<cols; c++) {
sb.append(String.format("%3s", (hasMine(r, c) ? "*" : "+")));
}
}
return sb.append("\n").toString();
}
public static void main(String ... args) {
System.out.println(new Playground(10, 10, 10));
}
}

Regular expressions are great, and you can actually do almost anything just with lots and lots of regular expressions. This does not mean that they are a good tool for all jobs.