如何将方法从布尔值转换为int（java）？

Question

so I have to build a Sudoku game in Java. I am able confirm in my method that the numbers 1 to 9 only appear once in each row/column. However, I have this set up as a boolean and can not for the life of me figure out how to convert this to an integer (so that I can return the row/column where the error occurs).

public static boolean rowColumnCheck(int[][] array) {

    for (int i = 0; i < 9; i++) {
        boolean[] rowArray = new boolean[9];
        boolean[] columnArray = new boolean[9];
        for (int j = 0; j < 9; j++) {
            int currentNumberRow = array[i][j];
            int currentNumberColumn = array[j][i];
            if ((currentNumberRow < 1 || currentNumberRow > 9)
                    && (currentNumberColumn < 1 || currentNumberColumn > 9)) {
                return false;
            }
            rowArray[currentNumberRow - 1] = true;
            columnArray[currentNumberColumn - 1] = true;

        }
        for (boolean booleanValue : rowArray) {
            if (!booleanValue) {
                return false;
            }
        }
        for (boolean booleanValue : columnArray) {
            if (!booleanValue) {
                return false;
            }
        }
    }
    return true;
}

Answer 1

You can't. Each method basically has just a return type and a boolean is not compatible with an Integer. What you could do is change the return type to Integer or to Pair if you need to return a set of coordinates and return null if is not there.

I guess it would be something like this. If null there was no error, and on the pair is the error location.

public static Pair rowColumnCheck(int[][] array) {

    Pair <Integer, Integer> p = null;

    for (int i = 0; i < 9; i++) {
        boolean[] rowArray = new boolean[9];
        boolean[] columnArray = new boolean[9];
        for (int j = 0; j < 9; j++) {
            int currentNumberRow = array[i][j];
            int currentNumberColumn = array[j][i];
            if ((currentNumberRow < 1 || currentNumberRow > 9)
                    && (currentNumberColumn < 1 || currentNumberColumn > 9)) {
                p = new Pair<Integer, Integer>(i, j);
                return p;
            }
            rowArray[currentNumberRow - 1] = true;
            columnArray[currentNumberColumn - 1] = true;

        }
        // Not really sure why you are doing this?
        for (boolean booleanValue : rowArray) {
            if (!booleanValue) {
                return null;
            }
        }
        for (boolean booleanValue : columnArray) {
            if (!booleanValue) {
                return null;
            }
        }
    }
    return null;
}

Answer 2

I have a feeling you want sometimes to return a row/column pair, sometimes a row, and sometimes a column. If this is right, then you need to create an extra class:

public class RowCol {
    public final int row;
    public final int col;

    public RowCol(int row, int col) {
        this.row = row;
        this.col = col;
    }
}

Now when you want to identify the place where the error occurred, you can

return new RowCol(i,j);

or to indicate a row without specifying a column

return new RowCol(i,-1);

and similarly for a column

return new RowCol(-1,j);

The return type of your method will be RowCol , and when you get one back from your method, you'll be able to interrogate its row and col fields to find out the co-ordinates of the return value.