Question

下面是我无法修复bug的代码。我无法正确使用箭头键移动对象。每当我使用箭头键在屏幕上移动对象时，它会移动几个像素然后停止。钥匙停止工作。我正在使用eclipse编译器。非常感谢帮助。谢谢！

import acm.program.*;
import acm.graphics.*;
import java.awt.*;
import java.awt.event.MouseEvent;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;

public class Ch10_Ex06_Draw_Star_Additions extends GraphicsProgram
{
    public void init ()
    {
        slider  = new JSlider (1, 150, 30);

        box = new JComboBox  ();
        box.addItem         ("White");
        box.addItem         ("Black");
        box.addItem         ("Red");
        box.addItem         ("Green");
        box.addItem         ("Blue");
        box.addItem         ("Orange");
        box.addItem         ("Yellow");
        box.setEditable     (false);
        box.setSelectedItem ("White");

        textField = new JTextField (20);
        textField.addActionListener (this);

        add (new JLabel  ("Small"), SOUTH);
        add (slider,                SOUTH);
        add (new JLabel  ("Large"), SOUTH);
        add (new JButton ("Clear"), SOUTH);
        add (new JLabel  ("Text"),  SOUTH);
        add (textField,             SOUTH);
        add (box,                   SOUTH);

        setBackground (Color.LIGHT_GRAY);

        addActionListeners  ();
        addKeyListeners     ();
        addMouseListeners   ();
    }

    public void keyPressed   (KeyEvent e)
    {
        if (e.getKeyCode() == KeyEvent.VK_DELETE)
            removeAll ();

        gobj = getElementAt (X, Y);

        if (gobj != null)
        {
            switch (e.getKeyCode ())
            {
            case KeyEvent.VK_UP:        gobj.move(0, -5);   break;
            case KeyEvent.VK_DOWN:      gobj.move(0, +5);   break;
            case KeyEvent.VK_LEFT:      gobj.move(-5, 0);   break;
            case KeyEvent.VK_RIGHT:     gobj.move(+5, 0);   break;
            }
        }
    }

    public void mouseClicked (MouseEvent e)
    {
        X = e.getX();
        Y = e.getY();

        star = new GStar    (slider.getValue());
        star.setFilled      (true);
        star.setColor       (getCurrentColor());
        star.setFillColor   (getCurrentColor());
        add (star, e.getX(), e.getY());
    }

    public void mousePressed (MouseEvent e)
    {
        point   = new GPoint    (e.getPoint());
        gobj    = getElementAt  (point);
    }

    public void mouseDragged (MouseEvent e)
    {
        if (gobj != null)
        {
            gobj.move (e.getX() - point.getX(), e.getY() - point.getY());
            point = new GPoint (e.getPoint());
        }
    }

    public void actionPerformed (ActionEvent e)
    {
        if (e.getActionCommand() == "Clear") 
            removeAll ();

        if (e.getSource() == textField)
        {
            GLabel label = new GLabel (textField.getText());
            String str = "Arial-" + slider.getValue() / 2;
            label.setColor (getCurrentColor());
            label.setFont(str);
            add (label,  X + star.getWidth()  , Y + star.getHeight()/4);
        }
    }

    private Color getCurrentColor()
    {
        String name = (String) box.getSelectedItem();
             if (name == "Red")     return Color.RED;
        else if (name == "Green")   return Color.GREEN;
        else if (name == "Blue")    return Color.BLUE;
        else if (name == "Orange")  return Color.ORANGE;
        else if (name == "Yellow")  return Color.YELLOW;
        else if (name == "Black")   return Color.BLACK;
        else                        return Color.WHITE;
    }

    private JTextField  textField;
    private JSlider     slider;
    private JComboBox   box;
    private GObject     gobj;
    private GPoint      point;
    private GStar       star;
    private int         X, Y;
}

Answer 1

你的物体正在移开，超出了＆＃34; X＆＃34;和＆＃34; Y＆＃34;只有在单击对象时才会获得。您应该在点击成员变量（例如，selectedObject）期间保存getElementAt（X，Y）返回的对象，然后使用它来移动它。

无法修复关键的按下事件功能

1 个答案: