Java MineSweeper: Calculating the amount of mines in a field

Question

I'm trying to make a basic MineSweeper game in Java.

I'm making a method which calculates the amount of mines that will be in the field, depending on the choice of difficulty made by the user.

Let's say the field has a total of 64 cells, and the user chose an "Advanced" difficulty. Let's say that 50% of the cells will be filled with mines, so there would be a total of 32 mines (field total magnitude / 100 * 50).

The problem I'm having is that the returning value is always 0.

This is the method I'm writing:

public int calculateMines () 
{
    int mines;
    mines = 0;

    float probability;
    probability = (float) 0.0;

    int magnitude;
    magnitude = 0;

    char dificulty;
    dificulty = '0';

    magnitude = this.getMagnitude();

    dificulty = this.getDificulty();

    switch (dificulty) 
    {
        case 'B':
        case 'b':
            probability = (float) ((magnitude/100) * 20);
        break;

        case 'I':
        case 'i':
            probability = (float) ((magnitude/100) * 30);
        break;

        case 'A':
        case 'a':
            probability = (float) ((magnitude/100) * 50);
        break;

        default:
            probability = -1;
            System.err.println("EEROR!");
        break;
    }

    mines = (int) probability;

    return mines;
}

What am I doing wrong?

Answer 1

If magnitude is less than 100 then probability will be 0 due to integer division. You could do

probability = (float) ((magnitude/100.0) * 20);