Не вижу в чем проблема
package com.javarush.games.minesweeper;
public class GameObject {
public int x;
public int y;
public boolean isMine;
public int countMineNeighbors;
public GameObject (int x, int y, boolean isMine) {
this.x = x;
this.y = y;
this.isMine = isMine;
}
}