谁拥有Java Swing可滚动视口边缘的颜色？

Question

我有一个带有JPanel的JScrollPane，它将Scrollable实现为视口视图。当我将ScrollableTracksViewportHeight和ScrollableTracksViewportWidth设置为false时，我的面板保持其首选大小。好。问题是我无法弄清楚谁拥有可滚动面板周围的空间。我觉得我已经尝试改变每个组件和对话框的背景，似乎没有做到这一点。如何将丑陋的灰色变成有趣的颜色，如霓虹黄？

以下是我正在谈论的截图：

这就是我想要的：

这是复制第一张图片的代码：

package components;

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

@SuppressWarnings("serial")
public class DialogWithScrollPane extends JFrame {

  ScrollablePanel scrollablePanel;

  public DialogWithScrollPane() {
    super();

    setResizable(true);

    Container pane = getContentPane();

    scrollablePanel = new ScrollablePanel();

    final JScrollPane scrollPane = new JScrollPane();
    scrollPane.setPreferredSize(new Dimension(300,300));
    scrollPane.setViewportView(scrollablePanel);
    scrollPane.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
    scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_ALWAYS);
    pane.add(scrollPane);

    setMinimumSize(new Dimension(300, 300));        
    setVisible(true);
  }

  class ScrollablePanel extends JPanel implements Scrollable {

    public ScrollablePanel() {
      super();

      setBackground(Color.red);
      setPreferredSize(new Dimension(200, 100));
    }

    public Dimension getPreferredScrollableViewportSize() {
      return getPreferredSize();
    }

    public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
      return 0;
    }

    public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
      return 0;
    }

    public boolean getScrollableTracksViewportHeight() {
      return false;
    }

    public boolean getScrollableTracksViewportWidth() {
      return false;
    }

  }

  public static void main(String[] args) {
    javax.swing.SwingUtilities.invokeLater(new Runnable() {
      public void run() {
        new DialogWithScrollPane();
      }
    });
  }
}

Answer 1

所有属于JViewport，您可以绘制任何所需的颜色，如here所示。

Answer 2

scrollPane.getViewport().setBackground(Color.yellow);