JTabbedPane为什么只有当我有多个标签时才有额外的填充? (代码和图片) [英] JTabbedPane why is there extra padding only when I have multiple tabs? (code and picture)

问题描述

我有一个JTabbed窗格，其中包含不同数量的选项卡.当突片的数量大于4，我得到额外的间距/填充在每个标签面板的底部.下图显示了这一点(在左侧看不到额外的间距，在右侧看不到额外的间距).

I have a JTabbed pane, which has a varying number of tabs. When the number of tabs is greater than 4, I get extra spacing/padding at the bottom of each tab panel. The picture below shows this (on the left you see the extra spacing, on the right you see no extra spacing).

这是我用来获取这些图片的确切代码:

Here is the exact code I used to get those pictures:

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTabbedPane;

public class DialogTest {

    public static void main(String[] args) {
        new DialogTest();
    }

    public DialogTest() {
        JDialog dialog = new MyDialog();
        dialog.pack();
        dialog.setVisible(true);
    }

    class MyDialog extends JDialog {

        public MyDialog() {
            super(null, ModalityType.APPLICATION_MODAL);

            final JTabbedPane tabs = new JTabbedPane();
            final int numTabs = Integer.parseInt(JOptionPane.showInputDialog("Number of tabs:"));

            setPreferredSize(new Dimension(400, 200));

            for (int i = 1; i <= numTabs; i++) {
                tabs.addTab("Tab"+i, new MyPanel(i));
            }

            setLayout(new BorderLayout());
            add(tabs, BorderLayout.NORTH);
        }
    }

    class MyPanel extends JPanel {
        public MyPanel(int text) {
            final JLabel label = new JLabel("THIS IS A PANEL" + text);
            label.setFont(label.getFont().deriveFont(18f));
            label.setBackground(Color.cyan);
            label.setOpaque(true);

            add(label);
            setBackground(Color.red);
        }   
    }
}

我尝试了很多事情，包括许多不同的布局管理器.我一生都无法摆脱多余的空间.任何帮助都会很棒.

I've tried numerous things including many different layout managers. I can't for the life of me get rid of that extra spacing. Any help would be great.

推荐答案

final JTabbedPane tabs = new JTabbedPane();
tabs.setTabLayoutPolicy(JTabbedPane.SCROLL_TAB_LAYOUT); // ADD THIS!

另一个示例如此操作的原因是，窗格将选项卡包装到下一行&假定一旦我们超出了可能在一行中自然显示的选项卡的数量，就必须增加首选大小以包括多余的选项卡行.

The reason the other example behaves as it does is that the pane wraps the tabs to the next line & presumes that once we have gone beyond as many tabs as it might naturally display in a single line, it must increase the preferred size to include that extra line of tabs.

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