Why is my random number generator becoming an unused assignment when using it to input values for 2d array?

I have been making a basic game of battleship and to get the CPU to choose ship locations on a 2d array I am making two random number generators to pick values from 1 to 8 on a separate method. For some reason, the random generators show up as unused and I don’t know why. so far this is what I have. If anyone knows what I’m doing wrong please let me know.

//calls method
board3 = CPUship(board3);
//displays result of method
for (int i = 0; i < board3.length; i++) {
    for (int j = 0; j < board3.length; j++) {
        System.out.print(board3[i][j]);
    }
    System.out.println("");
}

public static String[][] CPUship(String[][] board3) {
    int rowGenerate;
    int colGenerate;
    boolean valid2 = false;
    for (int CPUships = 0; CPUships < 6; CPUships++) {
        while (!valid2) {
            rowGenerate = (int) (9 * Math.random() + 0);
            colGenerate = (int) (9 * Math.random() + 0);
            if (!board3[rowGenerate][colGenerate].equalsIgnoreCase("#")) {
                board3[rowGenerate][colGenerate] = "#";
                valid2 = true;
            }
        }
        valid2 = false;
    }
    return board3;
}

Answer

Here should be a complete code

public static String[][] CPUship(String[][]board3){
    int rowGenerate;
    int colGenerate;
    
    for (int CPUships = 0; CPUships < 6; CPUships++) {
        boolean valid2=false;
        while (!valid2){ //instead of valid = false "
            rowGenerate = (int) ( 9* Math.random() + 0);
            colGenerate = (int) ( 9* Math.random() + 0);
            if (!board3[rowGenerate][colGenerate].equalsIgnoreCase ("#")){
                board3[rowGenerate][colGenerate]="#";
                valid2=true;
            }
            //removed the valid2=false, it does not "reset" automatically
            //removed the CPUships++ ... already done by the for loop 
        }
    }
    return board3;
}

or use break instead of the valid boolean

public static String[][] CPUship(String[][]board3){
    int rowGenerate;
    int colGenerate;
    
    for (int CPUships = 0; CPUships < 6; CPUships++) {
        while (true){ //instead of valid = false "
            rowGenerate = (int) ( 9* Math.random() + 0);
            colGenerate = (int) ( 9* Math.random() + 0);
            if (!board3[rowGenerate][colGenerate].equalsIgnoreCase ("#")){
                board3[rowGenerate][colGenerate]="#";
                break;
            }
            //removed the valid2=false, it does not "reset" automatically
            //removed the CPUships++ ... already done by the for loop 
        }
    }
    return board3;
}