java - 如何从另一个方法访问我在主方法中实例化的对象？

Question

我确信我错过了一些愚蠢的东西，这是我的代码:

public class clearBlankGrid {

    public static void main(String args[]) {

        Monster myMonster = new Monster(10,10,5,5,1);
        MonsterGUI myGUI = new MonsterGUI(myMonster);

        if (myMonster.getRows() > 0) {   
            // 0 = North, 1 = East, 2 = South, 3 = West
            myMonster.setFacing(3);
            myMonster.setIcon();
        }

    }

    public static void keepClearing() {

        myMonster.isGridCleared(); // Cannot find symbol 'myMonster'

    }

}

Answer 1

myMonster 如果您想在 keepClearing 方法(静态)中访问它，则需要是静态成员。

注意:作为引用，您还可以通过实际实例化 clearBlankGrid 类来避免将 Monster 成员设为静态。然后，Monster 可以是 clearBlankGrid 的实例变量，这意味着 keepClearing 方法不再必须是静态的。

public class clearBlankGrid {

   private Monster myMonster;
   private MonsterGUI myGUI;

   public void run() {
       myMonster = new Monster(10,10,5,5,1);
       myGUI = new MonsterGUI(myMonster);

       if (myMonster.getRows() > 0) {   
            // 0 = North, 1 = East, 2 = South, 3 = West
            myMonster.setFacing(3);
            myMonster.setIcon();
        }
   }

    public void keepClearing() {
        myMonster.isGridCleared();
    }

    public static void main(String args[]) {
        clearBlankGrid blankGrid = new clearBlankGrid();
        blankGrid.run();
    }
}