在卡片布局中充当流动布局的Gridbag布局.我究竟做错了什么

Question

此代码使用卡布局，因为我想更改窗口显示而不是具有多个窗口(或帧(。因此，我想要多个面板，这似乎有效。

但是，在面板中，我想将Gridbag布局用于定位组件。但这不起作用！它充当流程布局。谁能帮我克服这个障碍？请。

 import java.awt.*;
 import java.awt.event.*;
 import javax.swing.*;
 public class another
 {
private JPanel contentPane;
private MyPanel panel1;
private MyPanel2 panel2;
private void displayGUI()
{
    JFrame frame = new JFrame("Card Layout Example");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel contentPane = new JPanel();

    contentPane.setLayout(new CardLayout());
    panel1 = new MyPanel(contentPane);
    panel2 = new MyPanel2();
    contentPane.add(panel1, "Panel 1"); 
    contentPane.add(panel2, "Panel 2");
    frame.setContentPane(contentPane);
    frame.pack();   
    frame.setLocationByPlatform(true);
    frame.setVisible(true);
}
public static void main(String... args)
{
    SwingUtilities.invokeLater(new Runnable()
    {
        public void run()
        {
            new another().displayGUI();
        }
    });
}
}
class MyPanel extends JPanel {
private JTextField How;
private JLabel jcomp2;
private JLabel jcomp3;
private JButton jcomp4;
private JPanel contentPane;
private JPanel myPanel1;
public MyPanel(JPanel panel) 
{
    contentPane = panel;
    //construct components
    How = new JTextField (1);
    jcomp2 = new JLabel ("Label2");
    jcomp3 = new JLabel ("Label3");
    jcomp4 = new JButton ("openNewWindow");
    myPanel1 = new JPanel();
    //adjust size and set layout
    setPreferredSize (new Dimension (600, 600));
    setLayout (new GridBagLayout());
    //set component bounds (only needed by Absolute Positioning)
    /*
    How.setBounds (245, 50, 60, 25);
    jcomp2.setBounds (35, 30, 185, 50);
    jcomp3.setBounds (250, 30, 60, 20);
    jcomp4.setLocation(0, 0);
    jcomp4.setSize(315, 25);
    */


   insert(jcomp2, 0, 0, 1, 1); 
   insert(jcomp3, 0, 1, 1, 1); 
   insert(jcomp4, 1, 0, 1, 1);
    jcomp4.addActionListener( new ActionListener()
    {
        public void actionPerformed(ActionEvent e)
        {
            CardLayout cardLayout = (CardLayout) contentPane.getLayout();
            cardLayout.next(contentPane);
        }
    });
    //add components
    //add (How);
    add (jcomp2);
   add (jcomp3);
   add (jcomp4);               
}

public void insert(Component c, int gridX, int gridY, int gridW, int gridH)
{
  GridBagConstraints constraint = new GridBagConstraints();
  constraint.gridx = gridX;
  constraint.gridy = gridY;
  constraint.gridwidth = gridW;
  constraint.gridheight = gridH;
  constraint.anchor = GridBagConstraints.LINE_START;
  myPanel1.add(c, constraint);
}

}
class MyPanel2 extends JPanel {
private JButton jcomp1;
private JButton jcomp2;
private JButton jcomp3;
private JTextField jcomp4;
public MyPanel2() {
    //construct components
    jcomp1 = new JButton ("test1");
    jcomp2 = new JButton ("test2");
    jcomp3 = new JButton ("test3");
    jcomp4 = new JTextField (5);
    //adjust size and set layout
    setPreferredSize (new Dimension (395, 156));
    setLayout (null);
    //set component bounds (only needed by Absolute Positioning)
    jcomp1.setBounds (20, 45, 100, 25);
    jcomp2.setBounds (135, 60, 100, 25);
    jcomp3.setBounds (260, 35, 100, 25);
    jcomp4.setBounds (105, 115, 100, 25);
    //add components
    add (jcomp1);
    add (jcomp2);
    add (jcomp3);
    add (jcomp4);       
}
}

Answer 1

您看起来不必要地过于复杂。您可以创建一个名为ContentPane的Jpanel，并给它一个贴装，一切都很好，但是由于某种原因，您将contentpane jpanel传递到mypanel构造函数

JPanel contentPane = new JPanel();
contentPane.setLayout(new CardLayout());
panel1 = new MyPanel(contentPane); 
panel2 = new MyPanel2();

然后在构造函数中您将组件分配给相同的ContentPane Jpanel - 但是为什么呢？您将gridbaglayout分配给mypanel this实例，然后以gridbag的方式将组件添加到其内部的mypanel1变量中，而此jpanel具有jpanel jpanel默认default flowlayout：

class MyPanel extends JPanel {
    // ....
    private JPanel contentPane;
    private JPanel myPanel1;
    public MyPanel(JPanel panel) {
        contentPane = panel;
        // ....
        myPanel1 = new JPanel();
        setLayout (new GridBagLayout()); // you set *** this *** to GridBagLayout
        insert(jcomp2, 0, 0, 1, 1); 
        insert(jcomp3, 0, 1, 1, 1); 
        insert(jcomp4, 1, 0, 1, 1);
        add (jcomp2);  // and then you add components to this without GridBagConstraints ?
        add (jcomp3);
        add (jcomp4);               
    }

    public void insert(Component c, int gridX, int gridY, int gridW, int gridH) {
        // ....
        // but then add components in a GridBagLayout way into the myPanel1 JPanel???
        myPanel1.add(c, constraint);    
    }
}

最好将mypanel设置为使用GridBaglayout：

    // adjust size and set layout
    setPreferredSize(new Dimension(600, 600));
    // setLayout(new GridBagLayout());
    myPanel1.setLayout(new GridBagLayout());

而不是this

再次，您似乎过于复杂的是简单的努力。

例如：

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import javax.swing.*;
public class SimpleCardExample extends JPanel {
    private static final int EB_GAP = 8;
    private CardLayout cardLayout = new CardLayout();
    public SimpleCardExample() {
        setBorder(BorderFactory.createEmptyBorder(EB_GAP, EB_GAP, EB_GAP, EB_GAP));
        setLayout(cardLayout);
        add(new GridBagPanel(this), GridBagPanel.class.getSimpleName());
        add(new NextPanel(this), NextPanel.class.getSimpleName());
    }
    public void nextCard() {
        cardLayout.next(this);
    }
    private static void createAndShowGui() {
        JFrame frame = new JFrame("SimpleCardExample");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new SimpleCardExample());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}
class GridBagPanel extends JPanel {
    private static final int GAP = 6;
    private static final Insets GBC_INSETS = new Insets(GAP, GAP, GAP, GAP);
    public GridBagPanel(SimpleCardExample scExample) {
        setLayout(new GridBagLayout());
        add(new JLabel("Title Goes Here", SwingConstants.CENTER), createGbc(0, 0, 2, 1));
        add(new JLabel("Name:"), createGbc(0, 1, 1, 1));
        add(new JTextField(15), createGbc(1, 1, 1, 1));
        add(new JLabel("Phone:"), createGbc(0, 2, 1, 1));
        add(new JTextField(15), createGbc(1, 2, 1, 1));
        add(new JLabel("Address:"), createGbc(0, 3, 1, 1));
        add(new JTextField(15), createGbc(1, 3, 1, 1));
        add(new JButton(new NextAction("Next", scExample)), createGbc(0, 4, 2, 1));
    }
    private GridBagConstraints createGbc(int x, int y, int w, int h) {
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.gridx = x;
        gbc.gridy = y;
        gbc.gridwidth = w;
        gbc.gridheight = h;
        gbc.insets = GBC_INSETS;
        gbc.fill = GridBagConstraints.HORIZONTAL;
        gbc.anchor = x == 0 ? GridBagConstraints.WEST : GridBagConstraints.EAST;
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        return gbc;
    }
}
class NextPanel extends JPanel {
    public NextPanel(SimpleCardExample scExample) {
        add(new JButton(new NextAction("Next", scExample)));
    }
}
class NextAction extends AbstractAction {
    private SimpleCardExample scExample;
    public NextAction(String name, SimpleCardExample scExample) {
        super(name);
        this.scExample = scExample;
        int mnemonic = (int) name.charAt(0);
        putValue(MNEMONIC_KEY, mnemonic);
    }
    @Override
    public void actionPerformed(ActionEvent e) {
        scExample.nextCard();
    }
}