how to create magic square in java?

Question

my task is to write a program that ask user for an input and the method will return whether or not the input forms a magic square. No matter what I enter into the console, the p

Answer 1

Your outer loop in isMagicSquare is never entered, so you always return true.

Change

for(int x = 0; x > side; ++x)

to

for(int x = 0; x < side; ++x)

Beside that, sumD != magicNum should only be tested outside the outer loop, otherwise your method will return false in cases that should return true. And sumX and sumY should be reset in each iteration of the outer loop.

Therefore isMagicSquare() should look like this :

private static Boolean isMagicSquare(int[][] array){
    int side = array.length;
    int magicNum = 0;
    for(int x = 0; x < side; ++x){
        magicNum += array[0][x];
    }
    int sumD = 0;
    for(int x = 0; x < side; ++x){
        int sumX = 0;
        int sumY = 0;
        for (int y = 0; y < side; ++y){
            sumX += array[x][y];
            sumY += array[y][x];
        }
        sumD += array[x][x];
        if(sumX != magicNum  || sumY != magicNum){
            return false;
        }
    }
    return sumD == magicNum;
}

In addition, you forgot to add the inputs to ints :

do{
    System.out.print("Enter an int. Enter -1 when done>");
    current = Integer.parseInt(in.nextLine());
    if (current != -1) ints.add(current); // add this
}while(current != -1);

Answer 2

• You didn't save what is entered, so 0x0 square is passed to isMagicSquare().
• The implementation of isMagicSquare() is wrong in many points.
  • The condition x > side should be x < side.
  • You have to check sumD only after is calculation is finished.
  • You have to initialize sumX and sumY before calculating them.
  • You should use += instead of =+ to calculate the sum.

To correct:

Make the code save the input

do{
    System.out.print("Enter an int. Enter -1 when done>");
    current = Integer.parseInt(in.nextLine());
    if (current != -1) ints.add(current); // add this line to the loop to read the input
}while(current != -1);

and correct isMagicSquare().

private static Boolean isMagicSquare(int[][] array){
    int side = array.length;
    int magicNum = 0;
    for(int x = 0; x < side; ++x){
        magicNum += array[0][x];
    }
    int sumD = 0;
    for(int x = 0; x < side; ++x){
        int sumX = 0;
        int sumY = 0;
        for (int y = 0; y < side; ++y){
            sumX += array[x][y];
            sumY += array[y][x];
        }
        sumD =+ array[x][x];
        if(sumX != magicNum  || sumY != magicNum){
            return false;
        }
    }
    return sumD == magicNum;
}