this method must return a result of type boolean, java

Question

 public boolean Winner() {
    for (int z = 0; z < 3; z++) {
            if (board[z] != null && board[z] == board[z+3] && board[z] == board[z+6]
         


        

Answer 1

Right now, the function isn't guaranteed to return a boolean, because it's possible that neither of the if statements will ever be entered.

You could fix it like this (but only do this if it's actually what your logic needs!):

public boolean Winner() {
    for (int z = 0; z < 3; z++) {
            if (board[z] != null && board[z] == board[z+3] && board[z] == board[z+6]
                    ) {
                return true;
            } 
    }
    for(int i=0; i<7;i+=3){
        if (board[i] != null && board[i] == board[i+1] && board[i] == board[i+2]) {

    return true;}
    }

    return false;
}

Answer 2

All possible ways that the method can exit need to return something. If your code makes it through both for loops without having an if condition evaluate to true, then you need a return at the end that specifies what gets returned.

Answer 3

The Java compiler doesn't make assumptions that a for loop will have an iteration or that an if statement block will run.

There are execution paths where there is no return statement. What happens if the execution path doesn't execute any of the existing return statements and drops to the bottom? There isn't a return there.

Add a return at the bottom.

Answer 4

The answer to this question is easy. It happened to me too. The problem in your code is that you don't say to the computer what to do in case that the "if" statement is wrong, so you just have to add an "else {return false}" to every "if". Another tip is: please make your code cleaner and readable.

  public boolean Winner() {
    for (int z = 0; z < 3; z++) {
      if (board[z] != null && board[z] == board[z+3] && board[z] == board[z+6]) {
        return true;
      } else {
        return false;
      }
   } 
   for (int i=0; i<7; i+=3) {
     if (board[i] != null && board[i] == board[i+1] && board[i] == board[i+2]) {
       return true;
     } else {
       return false;
   }
  }
 }

Answer 5

The compiler is not aware that at least one of the loops will be executed. It takes into account all the possibilities of the execution and one of them is that neither of the loops will be executed and in that case there is no return statement. So insert a return statement out of the loops as well.