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.

public static String[][] CPUship(String[][]board3){
        boolean valid2=false;
        int rowGenerate=0;
        int colGenerate=0;
        int CPUships=0;
        
        while (CPUships<=5){
            while (valid2=false){
            rowGenerate = (int) ( 9* Math.random() + 0);
            colGenerate = (int) ( 9* Math.random() + 0);
            if (!board3[rowGenerate][colGenerate].equalsIgnoreCase ("#")){
                board3[rowGenerate][colGenerate]="#";
            valid2=true;
                }
            }
            CPUships++;
        }
        
        return board3;
        
        
    }