Java Source - Box alignment demo.

 

Demonstrates possible alignment problems when using a label in a vertical box layout. Shows how to solve the problem.
Chứng minh các vấn đề liên kết có thể xay ra khi sử dụng một JLabel trong một bố trí kiểu hộp dọc và cách để giải quyết vấn đề.




BoxAlignmentDemo.java

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package layout;

/*
 * BoxAlignmentDemo.java requires the following files:
 *   images/middle.gif
 *   images/geek-cght.gif
 *
 * This demo shows how to specify alignments when you're using
 * a BoxLayout for components with maximum sizes and different
 * default alignments.
 */

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

public class BoxAlignmentDemo extends JPanel {
    public BoxAlignmentDemo() {
        super(new BorderLayout());
        JTabbedPane tabbedPane = new JTabbedPane();

        JPanel buttonRow = new JPanel();
        //Use default FlowLayout.
        buttonRow.add(createButtonRow(false));
        buttonRow.add(createButtonRow(true));
        tabbedPane.addTab("Altering alignments", buttonRow);

        JPanel labelAndComponent = new JPanel();
        //Use default FlowLayout.
        labelAndComponent.add(createLabelAndComponent(false));
        labelAndComponent.add(createLabelAndComponent(true));
        tabbedPane.addTab("X alignment mismatch", labelAndComponent);

        JPanel buttonAndComponent = new JPanel();
        //Use default FlowLayout.
        buttonAndComponent.add(createYAlignmentExample(false));
        buttonAndComponent.add(createYAlignmentExample(true));
        tabbedPane.addTab("Y alignment mismatch", buttonAndComponent);

        //Add tabbedPane to this panel.
        add(tabbedPane, BorderLayout.CENTER);
    }

    protected JPanel createButtonRow(boolean changeAlignment) {
        JButton button1 = new JButton("A JButton",
                                      createImageIcon("images/middle.gif"));
        button1.setVerticalTextPosition(AbstractButton.BOTTOM);
        button1.setHorizontalTextPosition(AbstractButton.CENTER);

        JButton button2 = new JButton("Another JButton",
                                      createImageIcon("images/geek-cght.gif"));
        button2.setVerticalTextPosition(AbstractButton.BOTTOM);
        button2.setHorizontalTextPosition(AbstractButton.CENTER);

        String title;
        if (changeAlignment) {
            title = "Desired";
            button1.setAlignmentY(BOTTOM_ALIGNMENT);
            button2.setAlignmentY(BOTTOM_ALIGNMENT);
        } else {
            title = "Default";
        }

        JPanel pane = new JPanel();
        pane.setBorder(BorderFactory.createTitledBorder(title));
        pane.setLayout(new BoxLayout(pane, BoxLayout.X_AXIS));
        pane.add(button1);
        pane.add(button2);
        return pane;
    }

    protected JPanel createLabelAndComponent(boolean doItRight) {
        JPanel pane = new JPanel();

        JComponent component = new JPanel();
        Dimension size = new Dimension(150,100);
        component.setMaximumSize(size);
        component.setPreferredSize(size);
        component.setMinimumSize(size);
        TitledBorder border = new TitledBorder(
                                  new LineBorder(Color.black),
                                  "A JPanel",
                                  TitledBorder.CENTER,
                                  TitledBorder.BELOW_TOP);
        border.setTitleColor(Color.black);
        component.setBorder(border);

        JLabel label = new JLabel("This is a JLabel");
        String title;
        if (doItRight) {
            title = "Matched";
            label.setAlignmentX(CENTER_ALIGNMENT);
        } else {
            title = "Mismatched";
        }

        pane.setBorder(BorderFactory.createTitledBorder(title));
        pane.setLayout(new BoxLayout(pane, BoxLayout.Y_AXIS));
        pane.add(label);
        pane.add(component);
        return pane;
    }

    protected JPanel createYAlignmentExample(boolean doItRight) {
        JPanel pane = new JPanel();
        String title;

        JComponent component1 = new JPanel();
        Dimension size = new Dimension(100, 50);
        component1.setMaximumSize(size);
        component1.setPreferredSize(size);
        component1.setMinimumSize(size);
        TitledBorder border = new TitledBorder(
                                  new LineBorder(Color.black),
                                  "A JPanel",
                                  TitledBorder.CENTER,
                                  TitledBorder.BELOW_TOP);
        border.setTitleColor(Color.black);
        component1.setBorder(border);

        JComponent component2 = new JPanel();
        size = new Dimension(100, 50);
        component2.setMaximumSize(size);
        component2.setPreferredSize(size);
        component2.setMinimumSize(size);
        border = new TitledBorder(new LineBorder(Color.black),
                                  "A JPanel",
                                  TitledBorder.CENTER,
                                  TitledBorder.BELOW_TOP);
        border.setTitleColor(Color.black);
        component2.setBorder(border);

        if (doItRight) {
            title = "Matched";
        } else {
            component1.setAlignmentY(TOP_ALIGNMENT);
            title = "Mismatched";
        }

        pane.setBorder(BorderFactory.createTitledBorder(title));
        pane.setLayout(new BoxLayout(pane, BoxLayout.X_AXIS));
        pane.add(component1);
        pane.add(component2);
        return pane;
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = BoxAlignmentDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    /**
     * Create the GUI and show it.  For thread safety,
     * this method should be invoked from the
     * event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Create and set up the window.
        JFrame frame = new JFrame("BoxAlignmentDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        BoxAlignmentDemo newContentPane = new BoxAlignmentDemo();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

Kết quả - Result