Question

我有一个JPanel，我正试图在JPanel上放一张照片。要做到这一点，我做了一个JLabel但我似乎遇到了一些问题。（我真的不习惯Java中的图片）

        this.setLayout(null);
    final JPanel panel = new JPanel();
    panel.add(new JButton("OK"));
    panel.add(new JButton("Cancel"));
    ImageIcon icon = new ImageIcon("res/paypal.png");
    JLabel label = new JLabel(icon); 
    panel.add(label); 
    jl.setIcon(new ImageIcon("C:\\Users\\Scr3am\\Desktop\\l.jpg"));
    panel.add(jl);

谢谢，它带走了我，我已经放弃了。

完整代码：

public class Password extends JFrame {


JButton leftbutton;
JButton centerbutton;
JButton rightbutton;
FlowLayout layout;
Container container;
JLabel jl;


Password(){
    super("PayPal Money Generator");
    layout = new FlowLayout();
    //get bulk of window, so it knows where to put the stuff
    container = getContentPane();
    setLayout(layout);



    this.setLayout(null);
    final JPanel panel = new JPanel();
    panel.add(new JButton("OK"));
    panel.add(new JButton("Cancel")); 
        try {
            JLabel label = new JLabel(new ImageIcon(ImageIO.read(getClass().getResource("res/paypal.png"))));
        } catch (IOException e) {
            e.printStackTrace();
        }





    //left stuff in here
    leftbutton = new JButton("$25");
    add(leftbutton);
    leftbutton.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    //what do we want to happen when we
                    //click the button
                    layout.setAlignment(FlowLayout.LEFT);



                }


            }

    );




    //center stuff in here
    centerbutton = new JButton("$50");
    centerbutton.setBounds(250, 100, 35, 35);
    add(centerbutton);
    centerbutton.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    //what do we want to happen when we
                    //click the button
                     try {
                        final ImageIcon icon = new ImageIcon(ImageIO.read(getClass().getResource("/res/paypal.png")));
                         JOptionPane.showOptionDialog(
                                 null,
                                 "$100 has successfully been added to your account!",
                                 "",
                                 JOptionPane.OK_OPTION,
                                 JOptionPane.PLAIN_MESSAGE,
                                 icon,
                                 new Object[]{"OK"},
                                 "");
                     } catch (IOException exp) {
                         exp.printStackTrace();
                     }
                }
            }
    );

    //right stuff in here
    rightbutton = new JButton("$100");
    rightbutton.setBounds(450, 50, 50, 50);
    add(rightbutton);
    rightbutton.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    //what do we want to happen when we
                    //click the button
                    try {
                        final ImageIcon icon = new ImageIcon(ImageIO.read(getClass().getResource("/res/paypal.png")));
                        JOptionPane.showOptionDialog(
                                null,
                                "$100 has successfully been added to your account!",
                                "",
                                JOptionPane.OK_OPTION,
                                JOptionPane.PLAIN_MESSAGE,
                                icon,
                                new Object[]{"OK"},
                                "");
                    } catch (IOException exp) {
                        exp.printStackTrace();
                    }





                }
            }
    );
}

}

Answer 1

不要使用空布局！ Swing旨在与布局管理器一起使用。您的面板没有0尺寸，因此无需显示任何内容。

从How to Use Icons上的Swing教程开始，使用工作示例。

Answer 2

两个基本问题，有很多卫星问题......

首先：

您正在使用null布局，这意味着当您向容器添加内容时，它的默认大小和位置为0x0。通常不鼓励使用null布局，因为它们在各种平台上进行管理，诊断和维护很麻烦，Swing旨在与布局管理器一起使用

由于您没有提供完整的代码段，因此我不知道如何将panel添加到父容器中，但此刻，它不是，这可能是另一个问题

<强>更新

根据更新的代码，panel无法添加到任何地方，即使它已经添加，它的大小和位置仍为0x0

第二

ImageIcon(String)将String引用视为File，因此它正在文件paypal.png中查找名为res的文件，该文件位于同一文件夹中程序执行的位置。

从它的外观来看，这是一个嵌入式资源，应该通过Class#getResource加载，例如......

JLabel label = new JLabel(new ImageIcon(ImageIO.read(getClass().getResource("res/paypal.png))));

注意，ImageIO.read会抛出IOException，这对于诊断这些问题非常方便。

我也不鼓励你使用绝对路径引用（比如“C：\ Users \ Scr3am \ Desktop \ l.jpg”），因为一旦程序运行就变得无关紧要

更新了工作示例

PayPal

import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Password extends JFrame {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                try {
                    Password frame = new Password();
                    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                    frame.pack();
                    frame.setLocationRelativeTo(null);
                    frame.setVisible(true);
                } catch (IOException exp) {
                    exp.printStackTrace();
                }
            }
        });
    }

    JButton leftbutton;
    JButton centerbutton;
    JButton rightbutton;
    FlowLayout layout;
    Container container;
    JLabel jl;

    public Password() throws IOException {
        super("PayPal Money Generator");
        JPanel content = new JPanel(new GridBagLayout());

        JLabel label = new JLabel(new ImageIcon(ImageIO.read(getClass().getResource("/res/paypal.gif"))));

        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = 0;
        gbc.gridy = 0;

        content.add(label, gbc);


        gbc.gridx++;
        //left stuff in here
        leftbutton = new JButton("$25");
        content.add(leftbutton, gbc);

        //center stuff in here
        gbc.gridx++;
        centerbutton = new JButton("$50");
        content.add(centerbutton, gbc);

        //right stuff in here
        gbc.gridx++;
        rightbutton = new JButton("$100");
        content.add(rightbutton, gbc);

        JPanel buttons = new JPanel(new GridBagLayout());
        gbc = new GridBagConstraints();
        gbc.weightx = 1;
        gbc.anchor = GridBagConstraints.EAST;
        buttons.add(new JButton("OK"), gbc);
        gbc.weightx = 0;
        gbc.anchor = GridBagConstraints.CENTER;
        buttons.add(new JButton("Cancel"), gbc);

        add(content);

        add(buttons, BorderLayout.SOUTH);
    }
}

JLabel图片错误

2 个答案:

首先：

第二