如何使用另一个类中的代码？(JAVA)

Question

我正在进行坦克游戏,为了避免冗余,我正在进行课程扩展.我的MenuPanel看起来像这个atm(我只编写了对问题很重要的代码)(knop = dutch for button)

public class MenuPanel extends JPanel implements ActionListener
{

    private JButton playKnop, highScoreKnop, quitKnop, HTPKnop;
    private ImageIcon play, HS, quit, HTP;
    private Tanks mainVenster;

    public MenuPanel(Tanks mainVenster) 
    {
        this.mainVenster = mainVenster;
        this.setLayout(null); 

        int x = 95; 
        int width = 200; 
        int height = 50;    


        play = new ImageIcon(PlayPanel.class.getResource(/buttons/PLAY.png));
        playKnop = new JButton(play);
        playKnop.setBounds(x, y, width, height);
        playKnop.addActionListener(this);

        HS = new ImageIcon(PlayPanel.class.getResource(/buttons/HS.png));
        highScoreKnop = new JButton(HS);
        highScoreKnop.setBounds(x, 460, width, height);
        highScoreKnop.addActionListener(this);

        HTP = new ImageIcon(PlayPanel.class.getResource(/buttons/HTP.png));
        HTPKnop = new JButton(HTP);
        HTPKnop.setBounds(x, 515, width, height);
        HTPKnop.addActionListener(this);

        quit = new ImageIcon(PlayPanel.class.getResource(/buttons/QUIT.png));
        quitKnop = new JButton(quit);
        quitKnop.setBounds(x, 570, width, height);
        quitKnop.addActionListener(this);

        this.add(playKnop);
        this.add(quitKnop);
        this.add(HTPKnop);
        this.add(highScoreKnop);

        validate();
    }
}

因为制作按钮的代码完全相同(除了backgroundPath和y坐标)我创建了一个类按钮:

package menu;

import java.awt.Image;
import java.awt.event.ActionListener;

import javax.swing.ImageIcon;
import javax.swing.JButton;

public class button 
{


    public JButton button;
    public ImageIcon buttonImage;

    public int x = 95;
    public int width = 200;
    public int height = 50;

    public String backgroundPath;
    public int y;



    public button(String backgroundPath, int y)
    {
        this.backgroundPath = backgroundPath;
        this.y = y;

        buttonImage = new ImageIcon(PlayPanel.class.getResource(backgroundPath));
        button = new JButton();
        button.setBounds(x, y, width, height);;
        button.addActionListener(this); 
    }



}

这样,我的menuPanel可能看起来像这样:

    package menu;

    @SuppressWarnings("serial")
    public class MenuPanel extends JPanel implements ActionListener
    {

    private button playKnop, highScoreKnop, quitKnop, HTPKnop;
    private JTextField naam;
    private Tanks mainVenster;



    public MenuPanel(Tanks mainVenster) 
    {
        this.mainVenster = mainVenster;
        this.setLayout(null);       

        playKnop = new button("/buttons/PLAY.png", 350);        
        highScoreKnop = new button("/buttons/HS.png", 460);
        quitKnop = new button("/buttons/QUIT.png", 515);
        HTPKnop = new button("/buttons/HTP.png", 570);


        this.add(playKnop);
        this.add(quitKnop);
        this.add(HTPKnop);
        this.add(highScoreKnop);


        validate();

    }


}

我不知道为什么,但是当我这样做时,按钮将不会出现,虽然按钮类的代码是正确的(当我使用menuPanel本身的代码时,它工作)

我不知道如何解决这个问题,我在整个JavaProject中有很多这样的问题,但如果有人能解释我如何解决这个问题,我可以摆脱项目中的所有冗余.

谢谢,萝拉

非常感谢你们!你的答案的组合帮助我让按钮出现,但由于某种原因,图像不会加载它们.我的代码现在看起来像:

公共类MenuPanel扩展JPanel实现ActionListener {

private Button playKnop, highScoreKnop, quitKnop, HTPKnop;

private Tanks mainVenster;

int x = 95, width = 200, height = 50;

public MenuPanel(Tanks mainVenster) 
{
    this.mainVenster = mainVenster;
    this.setLayout(null);

    playKnop = new Button("/buttons/PLAY.png", 350, this);      
    highScoreKnop = new Button("/buttons/HS.png", 460, this);
    quitKnop = new Button("/buttons/QUIT.png", 515, this);
    HTPKnop = new Button("/buttons/HTP.png", 570, this);

    this.add(playKnop);
    this.add(quitKnop);
    this.add(HTPKnop);
    this.add(highScoreKnop);

    validate();

}

public class Button extends JButton
{
    JButton button;
    ImageIcon buttonImage;

    String backgroundPath;
    int y;


    public Button(String backgroundPath, int y, MenuPanel menuPanel)
    {
        super();
        this.backgroundPath = backgroundPath;
        this.y = y;

        buttonImage = new ImageIcon(PlayPanel.class.getResource(backgroundPath));
        this.setBounds(x, y, width, height);;
        this.addActionListener(menuPanel); 
    }
}

}

(所有按钮都能正常工作!)

Answer 1

你能观察到这两条线之间的区别吗：

playKnop.addActionListener(this);

以及后面代码中的一个：

playKnop = new button("/buttons/PLAY.png", 350);  

我相信您想添加MenuPanel为操作侦听器，但您没有在后面的代码中传递对它的引用。你应该更应该： playKnop = new button("/buttons/PLAY.png", 350, this);

然后在你的Button类中设置这个引用，如下所示：

public button(String backgroundPath, int y, MenuPanel menuPanel)
    {
        this.backgroundPath = backgroundPath;
        this.y = y;

        buttonImage = new ImageIcon(PlayPanel.class.getResource(backgroundPath));
        button = new JButton();
        button.setBounds(x, y, width, height);;
        button.addActionListener(menuPanel); 
    }