Question

我是Swing的新手，从另一个类开始一个窗口时遇到问题。如果我在同一个类中创建一个窗口的新对象，它就会很好地显示，但是当我尝试从另一个类启动它时它会显示为空。

这是我尝试过的，但它不起作用：

ProgressWindow dow = new ProgressWindow(this, null);

这里是我的Swing窗口的代码：

package example;

import java.awt.GridLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class ProgressWindow extends javax.swing.JFrame {

    private final JPanel panel;
    private final javax.swing.JLabel jLabel1;
    private final javax.swing.JLabel jLabel2;
    private String message = "Vorgang läuft...";
    private final int maxLength = 30;

    public ProgressWindow(JFrame frame, String pMessage) {
        super("Bitte warten");
        //Set Message
        setMessage(pMessage);
        //Labels und panel anlegen
        panel = new JPanel(new GridLayout(2, 1));
        jLabel1 = new javax.swing.JLabel();
        jLabel2 = new javax.swing.JLabel();
        //Position
        this.setLocationRelativeTo(frame);
        //Close-Operation
        setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
        //Size
        setMaximumSize(new java.awt.Dimension(240, 90));
        setMinimumSize(new java.awt.Dimension(240, 90));
        setResizable(false);
        //Content
        jLabel1.setText(message);
        jLabel2.setIcon(new javax.swing.ImageIcon(getClass().getResource("/xyz/ajax-loader.gif")));
        //Alignment
        jLabel1.setHorizontalAlignment(JLabel.CENTER);
        jLabel2.setHorizontalAlignment(JLabel.CENTER);
        //Finish Layout
        panel.add(jLabel1);
        panel.add(jLabel2);
        getContentPane().add(panel);
        pack();
        setVisible(true);
    }

    private void setMessage(String pMessage) {
        if (pMessage != null) {
            //Cut string if too long
            if (pMessage.length() > maxLength) {
                pMessage = pMessage.substring(0, maxLength) + "...";
            }
            this.message = pMessage;
        }
    }

    //This works as expected:
    public static void main(String[] args) {
        try {
            ProgressWindow pr = new ProgressWindow(null, null);
            Thread.sleep(2000);
            pr.dispose();
        }
        catch (InterruptedException ex) {
        }
    }
}

这是我用Netbeans GUI-Builder创建的一个快速而又脏的示例类，用于演示不起作用的代码：

package example;

public class Otherclass extends javax.swing.JFrame {

    public Otherclass() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jButton1)
                .addContainerGap(317, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jButton1)
                .addContainerGap(266, Short.MAX_VALUE))
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        try {
            ProgressWindow pr = new ProgressWindow(this, null);
            Thread.sleep(2000);
            pr.dispose();
        } catch (InterruptedException ex) {
            System.err.println(ex);
        }
    }                                        

    public static void main(String args[]) {
        /* Set the Nimbus look and feel */
        //<editor-fold defaultstate="collapsed" desc=" Look and feel setting code (optional) ">
        /* If Nimbus (introduced in Java SE 6) is not available, stay with the default look and feel.
         * For details see http://download.oracle.com/javase/tutorial/uiswing/lookandfeel/plaf.html 
         */
        try {
            for (javax.swing.UIManager.LookAndFeelInfo info : javax.swing.UIManager.getInstalledLookAndFeels()) {
                if ("Nimbus".equals(info.getName())) {
                    javax.swing.UIManager.setLookAndFeel(info.getClassName());
                    break;
                }
            }
        } catch (ClassNotFoundException ex) {
            java.util.logging.Logger.getLogger(Otherclass.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Otherclass.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Otherclass.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Otherclass.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }
        //</editor-fold>

        /* Create and display the form */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Otherclass().setVisible(true);
            }
        });
    }

    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    // End of variables declaration                   
}

Answer 1

在Swing应用程序中使用Swing Timer代替Thread.sleep(2000)。

了解更多How to Use Swing Timers

示例代码：

final ProgressWindow pr = new ProgressWindow(null, null);
Timer timer=new Timer(2000,new ActionListener() {

    @Override
    public void actionPerformed(ActionEvent arg0) {
       pr.dispose(); 
    }
});
timer.setRepeats(false);
timer.start();

Answer 2

您应该使用传递给构造函数的框架。

将构造函数中的调用更改为：

    frame.setDefaultCloseOperation(javax.swing.WindowConstants.DO_NOTHING_ON_CLOSE);
    //Size
    frame.setMaximumSize(new java.awt.Dimension(240, 90));
    frame.setMinimumSize(new java.awt.Dimension(240, 90));
    frame.setResizable(false);

    frame.getContentPane().add(panel);
    frame.pack();
    frame.setVisible(true);

从其他类使用时，Swing窗口为空

2 个答案: