java 动态创建 jCheckBox 并添加到 jScrollPane

Dynamically create jCheckBox and add to a jScrollPane

提问by wmdvanzyl

EDIT: Using the solutions presented below, I have changed the code to have a JPanel inside a JScrollPane. Using a JButton i add JCheckBoxes to the JPanel inside the JScrollPane. This was one problem solved, as the a JScrollPanecan only take one JComponent. The rest of the issues were solved setting a gridlayout to the JPanel inside JScrollPane. I have kept my original question here for the sake of posterity:

编辑：使用下面提供的解决方案，我已更改代码以在 JScrollPane 中包含一个 JPanel。使用 JButton 我将 JCheckBoxes 添加到 JScrollPane 内的 JPanel。这是一个问题解决了，因为一个 JScrollPane 只能接受一个 JComponent。其余的问题已解决，将 gridlayout 设置为 JScrollPane 内的 JPanel。为了后代，我把我原来的问题保留在这里：

ORIGINAL QUESTION: I'm trying to dynamically create JCheckBox and add them to a JScrollPane, but alas i am achieving little success. I have reduced this to a single proof-of-concept implementation.

原始问题：我正在尝试动态创建 JCheckBox 并将它们添加到 JScrollPane，但可惜我收效甚微。我已将其简化为单一的概念验证实现。

I have a JScrollPaneon a JPanel inside a JFrame. Also on the JPanel, i have added a button that is supposed to add a JCheckBox to the JScrollPane when clicked. Should be simple enough. The code inside the button is as follows:

我在 JFrame 中有一个 JScrollPaneon 一个 JPanel。同样在 JPanel 上，我添加了一个按钮，应该在单击时将 JCheckBox 添加到 JScrollPane。应该足够简单了。按钮内部的代码如下：

 private void addCheckBoxActionPerformed(java.awt.event.ActionEvent evt) {

    JCheckBox cb = new JCheckBox("New CheckBox");        

    jScrollPaneCheckBoxes.add(cb);
    jScrollPaneCheckBoxes.revalidate();
 }

The code runs seemingly without error. I have no exceptions and using the debugger shows that the JCheckBox is in fact added to the JScrollPane . Unfortunately, nothing is displayed in the application. I need direction as to where to look for the problem.

代码运行似乎没有错误。我没有例外，使用调试器显示 JCheckBox 实际上已添加到 JScrollPane 。不幸的是，应用程序中没有显示任何内容。我需要关于在哪里寻找问题的指导。

Here is a quick piece of code that you can just run. Unfortunately i threw this together using Netbeans and it's GUI designer and as such it's a bit longer than it needs to be, especially the generated code. Focus on the method jButton1ActionPerformed, that's where the above code is taken from.

这是一段您可以直接运行的快速代码。不幸的是，我使用 Netbeans 将它放在一起，它是 GUI 设计器，因此它比它需要的要长一些，尤其是生成的代码。关注 jButton1ActionPerformed 方法，这是上面代码的来源。

EDIT: This code now does what i need it to. :-)

编辑：这段代码现在做我需要的。:-)

package dynamiccheckboxsscce;

import javax.swing.JCheckBox;

public class Main extends javax.swing.JFrame {

    /**
     * Creates new form Main
     */
    public Main() {
        initComponents();
    }

    @SuppressWarnings("unchecked")
    private void initComponents() {

        jScrollPane1 = new javax.swing.JScrollPane();
        jPanel1 = new javax.swing.JPanel();
        jButton1 = new javax.swing.JButton();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        jScrollPane1.setHorizontalScrollBarPolicy(javax.swing.ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
        jScrollPane1.setPreferredSize(new java.awt.Dimension(250, 250));

        jPanel1.setPreferredSize(new java.awt.Dimension(300, 250));
        jPanel1.setLayout(new java.awt.GridLayout(0, 2, 10, 10));
        jScrollPane1.setViewportView(jPanel1);

        jButton1.setText("Add Checkbox");
        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()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, 309, Short.MAX_VALUE)
                .addContainerGap())
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addGap(0, 0, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addGap(112, 112, 112)))));
        layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, 11, Short.MAX_VALUE)
                .addComponent(jButton1)
                .addContainerGap()));

        pack();
    }

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
        JCheckBox cb = new JCheckBox("New CheckBox");

        jPanel1.add(cb);
        jPanel1.revalidate();
        jPanel1.repaint();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        /*
         * Set the Nimbus look and feel
         */
        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(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (InstantiationException ex) {
            java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (IllegalAccessException ex) {
            java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
            java.util.logging.Logger.getLogger(Main.class.getName()).log(java.util.logging.Level.SEVERE, null, ex);
        }

        /*
         * Create and display the form
         */
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new Main().setVisible(true);
            }
        });
    }
    private javax.swing.JButton jButton1;
    private javax.swing.JPanel jPanel1;
    private javax.swing.JScrollPane jScrollPane1;
}

Thanks in advance.

提前致谢。

回答by mKorbel

• without posting a SSCCEyou have to accepting that JScrollPaneis designated to nest only one JComponent,

• if you want to add more that one JComponentto the JScrollPane, the put there JPaneland then add a new JComponentto the JPanelinstead of JScrollPane

• to check how dynamically add / remove JComponents

• 在不发布SSCCE 的情况下，您必须接受JScrollPane被指定为仅嵌套一个JComponent，

• 如果您想向 中添加更多，JComponent则将JScrollPane其放在JPanel 中，然后向 中添加一个新JComponent的JPanel而不是JScrollPane

• 检查如何动态添加/删除 JComponents

EDIT

编辑

• you have to set proper LayoutManager to the JPanel

• you ahve to add JPanel to the JScrollPane

• for example (without using built_in designer, even safe time for ..., required best knowledge about used SwingFramework and Swing too, I'm satisfied with plain Swing)

• 您必须为 JPanel 设置适当的 LayoutManager

• 你必须将 JPanel 添加到 JScrollPane

• 例如（不使用内置设计器，即使是安全时间...，也需要有关使用过的 SwingFramework 和 Swing 的最佳知识，我对普通 Swing 感到满意）

code

代码

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;

public class AddJCheckBoxToJScrollPane {

    private static final long serialVersionUID = 1L;
    private JFrame frame = new JFrame();
    private JButton jButton1;
    private JPanel jPanel1;
    private JScrollPane jScrollPane1;

    public AddJCheckBoxToJScrollPane() {
        jPanel1 = new JPanel();
        jPanel1.setLayout(new GridLayout(0, 2, 10, 10));
        jScrollPane1 = new JScrollPane(jPanel1);
        jButton1 = new JButton("Add Checkbox");
        jButton1.addActionListener(new java.awt.event.ActionListener() {

            public void actionPerformed(java.awt.event.ActionEvent evt) {
                JCheckBox cb = new JCheckBox("New CheckBox");
                jPanel1.add(cb);
                jPanel1.revalidate();
                jPanel1.repaint();
            }
        });
        frame.add(jScrollPane1);
        frame.add(jButton1, BorderLayout.SOUTH);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(300, 200);
        //frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String args[]) {

        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) {
        } catch (InstantiationException ex) {
        } catch (IllegalAccessException ex) {
        } catch (javax.swing.UnsupportedLookAndFeelException ex) {
        }
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new AddJCheckBoxToJScrollPane();
            }
        });
    }
}

回答by Charles

You should be calling repaint() instead of revalidate().

您应该调用 repaint() 而不是 revalidate()。

See Revalidate vs. Repaint

请参阅重新验证与重绘