使用Java1.6中的Swing库构建简单的GUI

我正在尝试使用Swing库构建一个简单的GUI。我不明白为什么我的表会删除以前添加到GUI中的所有内容，然后才创建表。我假设它是addMainPanel中的某个命令，但我不确定是哪个命令。如蒙指教，不胜感激

package fuelConsumption;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.*;

public class LogView implements ActionListener {

    private Log myLog;
    private JFrame frame;

    public LogView (String frameName) {
        this.frame = new JFrame(frameName);
        this.frame.setPreferredSize(new Dimension(500,500));
        this.frame.getContentPane().setLayout(new BorderLayout());

        this.addMainPanel(frame);
        this.addTable(frame);
        //addMenu(frame);
        //addToolBar(frame);

        this.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.frame.pack();
        this.frame.setVisible(true);
    }

    private void addTable(JFrame frame2) {
        String[] columnNames = {"date",
                               "station",
                               "fuel grade",
                               "fuel amount",
                               "fuel unit cost",
                               "fuel cost",
                               "trip distance"};
        Object[][] data = {
            {"Shell", 89, 40, 109.5, "bla", 100, 123}
        };

        JTable table = new JTable(data, columnNames);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        //table.setFillsViewportHeight(true);

        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);

        //Add the scroll pane to this panel.
        //this.frame.setContentPane(scrollPane);
        frame2.getContentPane().add(scrollPane);
    }

    private void addMainPanel(JFrame frame2) {
        // TODO Auto-generated method stub

        JPanel panel = new JPanel(new GridBagLayout());

        GridBagConstraints c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 0;
        c.gridwidth = 5;
        c.ipady = 50;
        c.anchor = GridBagConstraints.LINE_START;
        c.weightx = 0.5;
        c.weighty = 0.5;
        JLabel label = new JLabel("");
        panel.add(label,c);

        label = new JLabel("Info");
        c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 1;
        c.anchor = GridBagConstraints.LINE_START;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(label,c);

        label = new JLabel("Label");
        c = new GridBagConstraints();
        c.gridx = 2;
        c.gridy = 1;
        c.anchor = GridBagConstraints.LINE_START;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(label,c);

        label = new JLabel("Comments");
        c = new GridBagConstraints();
        c.gridx = 0;
        c.gridy = 2;
        c.anchor = GridBagConstraints.FIRST_LINE_START;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(label,c);

        JTextArea textArea = new JTextArea(4,30);
        JScrollPane textScroll = new JScrollPane(textArea);
        c = new GridBagConstraints();
        c.gridx = 1;
        c.gridy = 2;
        c.gridwidth = 4;
        c.ipadx = 30;
        c.ipady = 50;
        c.anchor = GridBagConstraints.FIRST_LINE_START;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(textScroll,c);

        JButton button = new JButton("Edit");
        button.addActionListener(this);
        button.setActionCommand("Edit");
        c = new GridBagConstraints();
        c.gridx = 1;
        c.gridy = 3;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(button,c);

        button = new JButton("Previous");
        button.addActionListener(this);
        button.setActionCommand("Previous");
        c = new GridBagConstraints();
        c.gridx = 2;
        c.gridy = 3;
        c.weightx = 0.5;
        c.weighty = 0.5;
        panel.add(button,c);

        button = new JButton("Next");
        button.addActionListener(this);
        button.setActionCommand("Next");
        c = new GridBagConstraints();
        c.gridx = 3;
        c.gridy = 3;
        //        c.weightx = 0.5;
        //        c.weighty = 0.5;
        panel.add(button,c);

        frame2.getContentPane().add(panel);
    }

    public static void main(String [] args){
        new LogView("Fuel Consumption");
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // TODO Auto-generated method stub

    }
}

---

JFrame

的默认布局是，因此在

addTable

和

addMainPanel

方法中分别需要类似的内容：

frame2.add(scrollPane, BorderLayout.CENTER);
frame2.add(panel, BorderLayout.SOUTH);

请注意，

getContentPane（）

不是必需的。

您的GUI可以是：

如果你改变

private void addTable（JFrame frame2）{

to

private void addTable（）{

及

frame2.getContentPane（）.add（滚动窗格）；

到

frame.add（滚动窗格，BorderLayout.CENTER）；

致：

private void addMainPanel（JFrame frame2）{

to

private void addMainPanel（）{

及

frame2.getContentPane（）.add（面板）；

到

frame.add（面板，BorderLayout.SOUTH）；

因为在中只有一个可以放置在其中一个区域中，因为没有BorderLayout常量的定义，所以JComponent将放置在

BorderLayout.CENTER

区域中

(三)

那你得换衣服了

this.addMainPanel(frame);
this.addTable(frame);

到

---

您正在混合布局、组件

如果要将面板和表格作为两个单独的组件（而不是面板内的表格）添加到框架中，应注意框架的布局，

BorderLayout

。应使用布局指示将面板和表格添加到框架中以放置组件，如：

 frame2.getContentPane().add(scrollPane, BorderLayout.SOUTH);

及

---

+1正如您所观察到的，更常见的情况是容器层次结构符合词法范围，例如，返回面板而不是传递容器。

 frame2.getContentPane().add(scrollPane, BorderLayout.SOUTH);

frame2.getContentPane().add(panel, BorderLayout.NORTH);