动态 JPanel 添加答案

【问题标题】：Dynamic JPanel addition动态 JPanel 添加
【发布时间】：2011-10-14 05:07:18
【问题描述】：

我正在尝试创建一个动态的 Swing GUI。当我点击添加/删除按钮时，我需要添加/删除JPanels。我无法动态添加JPanels。最初JPanel 加载但JPanels 的数组无法工作。我该怎么做？

import java.awt.*;
import java.awt.event.*;
import java.io.*;

import javax.print.attribute.standard.JobHoldUntil;
import javax.swing.*;

public class AccessoryFileChooser2 extends JFrame {
  JFileChooser chooser = null;
  JLabel statusbar;
  JLabel file;
  JCheckBox checkBox;
  int count;
  int increment;
  JPanel [] panel = new JPanel[10]; //array

  public AccessoryFileChooser2() {
    setSize(350, 200);
    count=0;
    increment=1;
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    final Container c = getContentPane();

    c.setLayout(new BorderLayout());
    checkBox =new JCheckBox("");
    String fileName = "Choose File Name";
   file = new JLabel(fileName);
    final JButton accButton = new JButton("Browse");
    final JButton add = new JButton("Add");
    final JButton validate = new JButton("Validate");
    final JButton delete = new JButton("Delete");

    accButton.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent ae) {
        int option = chooser.showOpenDialog(AccessoryFileChooser2.this);
        if (option == JFileChooser.APPROVE_OPTION) {
          statusbar.setText(
           (
            chooser.getSelectedFile().getPath()));
        }
      }
    });

    statusbar = new JLabel("Output of your selection will go here");
    chooser = new JFileChooser();


   final JPanel panels =new JPanel();

   //JPanel panel2 =new JPanel();
   panel[count]=new JPanel();
   panel[count].add(checkBox);
   panel[count].add(file);
   panel[count].add(accButton );
   panel[count].add(statusbar);
   c.add(panel[count],BorderLayout.CENTER);
   panels.add(add);
   panels.add(delete);
   panels.add(validate);

   add.addActionListener(new ActionListener() {

       public void actionPerformed(ActionEvent e)
       {
          count=count+1;;
          increment=increment+1;;
          panel[count]=new JPanel();
           System.out.println("You clicked the ADD button");

           panel[count].add(checkBox);
           panel[count].add(file);
           panel[count].add(accButton );
           panel[count].add(statusbar);
           panel[count].revalidate();
           panel[count].repaint();
           panel[count].updateUI();
           c.add(panel[count]);

       }
   });

   delete.addActionListener(new ActionListener() {

       public void actionPerformed(ActionEvent e)
       {
           increment--;
           System.out.println("You clicked the Delete button");
           System.out.println(checkBox.isSelected());
           for (int i = 0; i < panel.length; i++) {
               JCheckBox box=(JCheckBox) panel[i].getComponent(0);
               if(box.isSelected()){
   c.remove(panel[i]);
   }
        }

       }
   });

   validate.addActionListener(new ActionListener() {

       public void actionPerformed(ActionEvent e)
       {
           System.out.println("You clicked the Validate button");
       }
   });


   c.add(panels,BorderLayout.SOUTH);

  }

  public static void main(String args[]) {
    AccessoryFileChooser2 afc = new AccessoryFileChooser2();
    afc.setVisible(true);
  }
}

【问题讨论】：

标签： swing jpanel java

【解决方案1】：

不是说不正确，新手错误很多，

1/ 因为与您为JPanels 创建数组的方式相同

JPanel [] panel = new JPanel[10];

你需要为其JComponents创建Array，因为一个JComponent一次只能添加一次

编辑：部分修改/更改的代码显示了这个问题

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;

public class AccessoryFileChooser2 extends JFrame {

    private static final long serialVersionUID = 1L;
    private JFileChooser chooser = null;
    private JLabel statusbar;
    private JLabel file;
    private JCheckBox checkBox;
    private int count;
    private int increment = 10;
    private JPanel parentPanel = new JPanel();
    private JPanel panels = new JPanel();
    private JPanel[] panel = new JPanel[increment]; //array
    private JButton accButton = new JButton("Browse");
    private JButton addButton = new JButton("Add");
    private JButton validate = new JButton("Validate");
    private JButton delete = new JButton("Delete");

    public AccessoryFileChooser2() {
        count = 0;
        parentPanel.setLayout(new GridLayout(10, 1, 10, 10));
        checkBox = new JCheckBox("");
        String fileName = "Choose File Name";
        file = new JLabel(fileName);
        accButton.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent ae) {
                int option = chooser.showOpenDialog(AccessoryFileChooser2.this);
                if (option == JFileChooser.APPROVE_OPTION) {
                    statusbar.setText((chooser.getSelectedFile().getPath()));
                }
            }
        });
        statusbar = new JLabel("Output of your selection will go here");
        chooser = new JFileChooser();
        panel[count] = new JPanel();
        panel[count].add(checkBox);
        panel[count].add(file);
        panel[count].add(accButton);
        panel[count].add(statusbar);
        panel[count].setPreferredSize(new Dimension(450, 40));
        panel[count].setBorder(new LineBorder(Color.BLACK, 1));
        parentPanel.add(panel[count]);
        addButton.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                if (count < increment - 1) {
                    count += 1;
                    panel[count] = new JPanel();
                    System.out.println("You clicked the ADD button");
                    panel[count].add(checkBox);
                    panel[count].add(file);
                    panel[count].add(accButton);
                    panel[count].add(statusbar);
                    panel[count].revalidate();
                    panel[count].repaint();
                    //panel[count].updateUI();
                    parentPanel.add(panel[count]);
                    parentPanel.revalidate();
                    parentPanel.repaint();
                    pack();
                    if (count == increment - 1) {
                        addButton.setEnabled(false);
                    }
                }
            }
        });
        delete.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                System.out.println("You clicked the Delete button");
                System.out.println(checkBox.isSelected());
                /*for (int i = 0; i < parentPanel.getComponentCount(); i++) {
                JCheckBox box = (JCheckBox) panel[i].getComponent(0);
                if (box.isSelected()) {
                parentPanel.remove(panel[i]);
                }
                }*/
            }
        });
        validate.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e) {
                System.out.println("You clicked the Validate button");
            }
        });
        panels.setLayout(new GridLayout(1, 3, 10, 10));
        panels.add(addButton);
        panels.add(delete);
        panels.add(validate);
        add(parentPanel, BorderLayout.CENTER);
        add(panels, BorderLayout.SOUTH);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
        setVisible(true);
    }

    public static void main(String args[]) {
        AccessoryFileChooser2 afc = new AccessoryFileChooser2();
    }
}

将此输出到 GUI

2/ 以此类推...

不要这样做，可能会出现很多性能问题，如果您多次添加和删除JPanel[] ...，GUI 将冻结或无响应

最好按照here 的建议寻找JTable 和一个TableColumn

【讨论】：

非常感谢。是的，我是 Swings 的新手。所以尝试一些事情来熟悉。

【解决方案2】：

在可见的 GUI 中添加或删除组件时，一般代码应为：

panel.add(...);
panel.revalidate();
panel.repaint();

重新验证基本上调用布局管理器。

重绘确保组件在布局发生变化时被重绘。

【讨论】：

嗨，它适用于我 revalidate();只是，repaint() 方法是必要的吗？为什么？
@MarwenTrabelsi，当你只添加一个组件时，repaint() 通常是没有必要的。但是，有时如果您删除然后添加一个组件，您可能需要强制重新绘制，因为布局管理器可能认为面板大小相同并且不调用 repaint()。

【解决方案3】：

我已经成功了：

repaint();
validate();

在运行时对 gui 进行更改后。当我创建、删除、移动面板时，我会在组件/容器上调用这两个方法。

【讨论】：

【解决方案4】：

在c.add(panel[count]); 之后添加c.validate() 以更新GUI。

还建议检查JPanels的当前数量，因为这样你会很快得到ArrayIndexOutOfBoundsException...

【讨论】：

它有帮助吗？根据文档，您必须在 add 之后调用它
我添加了 c.validate 因为 c.revalidate 不存在。但它仍然无法正常工作。感谢您的回复。
尝试之前拨打invalidate()