Question

所以基本上，我正在做一个游戏任务，我正在尝试创建关键命令。到目前为止唯一不起作用的是addKeyListener(**this**)。我尝试修复它但最终破坏了我的整个程序。到目前为止我的代码是：

public static void main (String[] args)
    throws InterruptedException {
    for (int x = 0 ; x < 999 ; x++)
    {
        int lvl = 0;
        int line = 0;
        write ();
        line = start (line);
        for (int p = 0 ; p < 999 ; p++)
        {
            if (line == 0)
            {
                System.out.println ("Select a level (1-3)");
                lvl = In.getInt ();
                if (lvl == 1)
                {
                    JFrame gamu = new JFrame ("Hoops 1.0");                        //JFrame that runs a game in a window
                    Culminating_MingxuanHe ball = new Culminating_MingxuanHe ();
                    gamu.getContentPane ().add (ball);
                    gamu.setSize (400, 480);       //sets the size for the game
                    gamu.setVisible (true);
                    ball.addKeyListener (this);
                    gamu.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);   //closes program when game is closed
                    while (true)
                    {
                        ball.moveBall ();       //runs the methods
                        ball.repaint ();
                        Thread.sleep (8);     //speed of the square
                    }
                }
                }
        }
        if (line == 1)
        {
            System.out.println ("Goodbye, have a nice day");
            x = 999;
        }
    }
}


int a = 200, s = 1, d = 100, f = 1;     //initial position of the square
int q = 150, w = 430, e = 80, r = 10;
int plat = 149;
int plat2 = 81;
int mov = 10;

public void moveBall ()
{
    if (a + s < 0)      //border on left
        s = 1;
    if (a + s > getWidth () - 25)      //border on right
        s = -1;
    if (d + f < 0)         //border on top
        f = 1;
    if (d + f > getHeight () - 25)  //border on bottom
        f = -1;
    a = a + s;           //moves the ball
    d = d + f;
}

public void KeyboardExample ()
{
    KeyListener listener = new keyPressed ();
    addKeyListener (listener);
    setFocusable (true);
}


public void keyPressed (KeyEvent e)
{
    int key = e.getKeyCode ();
    if (key == KeyEvent.VK_LEFT)
    {
        plat = plat - mov;
    }
    if (key == KeyEvent.VK_RIGHT)
    {
        plat = plat + mov;
    }
}


public void keyTyped (KeyEvent e)
{
}


public void keyReleased (KeyEvent e)
{
}

}

Answer 1

您正在尝试访问对象的实例。你不能那样做，因为main方法是静态的。静态方法是CLASS的一部分，实例方法是OBJECT的一部分。你在代码中所做的是尝试访问你曾经称之为main的对象（即variable.main），但它没有用，因为没有对象。希望这有助于：）

Answer 2

这种格式适用于在Java SE中保持Swing内容的整洁。

class YourClass extends JFrame {
    // variables or constants required for the frame
    public YourClass() {
        /*
        set frame properties, add listeners, and here 'this' (referring to the YourClass instance) will work since its in a non static context
        */
    }
    /*
    add methods to be executed when events are triggered according to the listener specified in the above constructor
    */
}

public class TestClass {
    /*
    here goes your main method and create the instance of the YourClass class and call setVisible(true)
    */
}

“这个”在我的程序中不起作用

2 个答案: