java - JPanel从其原始位置向外动态生成

Question

我在 JPanel 内动态生成一些文本框和标签，但是当我将该面板放置在 JTabbedPane 内时，它不会在其原始位置内生成。它总是去别的地方。

JFrame 类构造函数内的代码:

    panel = jPanel1;
    panel.setLayout(new FlowLayout());
    add(panel, BorderLayout.LINE_START);
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setVisible(true);

JButton 内的代码:

    JLabel lbl = new JLabel();
    lbl.setText("Label");
    panel.add(lbl);

    JTextField txt = new JTextField(12);
    txt.setText("Text field");
    panel.add(txt);
    panel.revalidate();
    validate();

该按钮用于动态生成文本框和标签。 jPanel1 是放置在框架内的面板。它可以完美地直接放置在框架内，但在放置在选项卡式 Pane 内后，它会变得困惑。

有没有办法在生成组件后刷新面板并删除其中的组件？

这是完整的 Jframe 类:

import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.LayoutManager;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author sajithru
 */
public class DynamicTextboxes extends javax.swing.JFrame {

    /**
     * Creates new form DynamicTextboxes
     */
    private JPanel panel;

    public DynamicTextboxes() {
        initComponents();
        panel = jPanel1;
        panel.setLayout(new FlowLayout());
        add(panel, BorderLayout.LINE_START);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    /**
     * This method is called from within the constructor to initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is always
     * regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jTabbedPane1 = new javax.swing.JTabbedPane();
        jPanel1 = new javax.swing.JPanel();

        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 jPanel1Layout = new javax.swing.GroupLayout(jPanel1);
        jPanel1.setLayout(jPanel1Layout);
        jPanel1Layout.setHorizontalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 206, Short.MAX_VALUE)
        );
        jPanel1Layout.setVerticalGroup(
            jPanel1Layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 258, Short.MAX_VALUE)
        );

        jTabbedPane1.addTab("tab1", jPanel1);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(190, 190, 190)
                .addComponent(jButton1)
                .addContainerGap(216, Short.MAX_VALUE))
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap(javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jTabbedPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 211, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(18, 18, 18))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGap(16, 16, 16)
                .addComponent(jTabbedPane1, javax.swing.GroupLayout.PREFERRED_SIZE, 286, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButton1)
                .addContainerGap(40, Short.MAX_VALUE))
        );

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

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        // TODO add your handling code here:
        JLabel lbl = new JLabel();
        lbl.setText("Label");
        panel.add(lbl);

        JTextField txt = new JTextField(12);
        txt.setText("Text field");
        panel.add(txt);
        panel.revalidate();
        validate();
    }                                        

    /**
     * @param args the command line arguments
     */
    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(DynamicTextboxes.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(DynamicTextboxes.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(DynamicTextboxes.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(DynamicTextboxes.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 DynamicTextboxes().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JTabbedPane jTabbedPane1;
    // End of variables declaration
}

Answer 1

我怀疑您正在使用 setBounds() 或类似的方法将组件放置在 Container 中，该容器有一些(默认)布局等待您的调用到revalidate()。相反，请在调用 setVisible() 之前在封闭的 Window 上调用 pack()。

附录:我尝试使用 pack() ...但结果仍然相同。

您的布局正在切断新行。下面的示例使用 pack() 来调整封闭Window 的大小。此相关example说明了 revalidate() 和 repaint()。还可以考虑使用 JScrollPane，参见 here .

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

/**
 * @see https://stackoverflow.com/a/17165034/230513
 */
public class DynamicTextboxes extends javax.swing.JFrame {

    /**
     * Creates new form DynamicTextboxes
     */
    public DynamicTextboxes() {
        initComponents();
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jTabbedPane1 = new javax.swing.JTabbedPane();
        jPanel1 = new javax.swing.JPanel(new GridLayout(0, 1));
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        jButton1.setText("jButton1");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });
        jPanel1.add(createPanel());
        jTabbedPane1.addTab("tab1", jPanel1);
        add(jTabbedPane1);
        JPanel p = new JPanel();
        p.add(jButton1);
        add(p, BorderLayout.SOUTH);
        pack();
        setLocationByPlatform(true);
    }

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        jPanel1.add(createPanel());
        pack();
    }

    private JPanel createPanel() {
        JPanel p = new JPanel();
        JLabel lbl = new JLabel();
        lbl.setText("Label");
        p.add(lbl);
        JTextField txt = new JTextField(12);
        txt.setText("Text field");
        p.add(txt);
        return p;
    }

    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new DynamicTextboxes().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify
    private javax.swing.JButton jButton1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JTabbedPane jTabbedPane1;
    // End of variables declaration
}