如果添加的按鈕太多，JToolBar顯示箭頭

Question

當可見容器小於所有按鈕需要的空間時，是否有方法在JToolBar（API）中有一個箭頭（如）？

（爲了說明的目的見WebUI zkoss）

UI管理器（L & F）應該是擺動的正常之一。

Answer 1

有沒有辦法有一個箭頭

這不是API的一部分，所以你需要創建自己的。

您可能可以使用以下內容給您一些建議。這方面的例子添加按鈕左/右時，有沒有對所有的按鈕足夠的空間，讓您可以滾動查看每個按鈕：按要求

import java.awt.*; 
import java.util.List; 
import java.util.ArrayList; 
import java.awt.event.*; 
import javax.swing.*; 
import javax.swing.plaf.basic.*; 


public class ScrollContainer extends JPanel 
    implements ActionListener, ComponentListener 
{ 
    private Container container; 
    private List<Component> removedComponents = new ArrayList<Component>(); 
    private JButton forwardButton; 
    private JButton backwardButton; 

    public ScrollContainer(Container container) 
    { 
     this.container = container; 
     setLayout(new BorderLayout(5, 0)); 
     addComponentListener(this); 

     // Create buttons to control scrolling 

     backwardButton = new BasicArrowButton(BasicArrowButton.WEST); 
     configureButton(backwardButton); 
     forwardButton = new BasicArrowButton(BasicArrowButton.EAST); 
     configureButton(forwardButton); 

     // Layout the panel 

     add(backwardButton, BorderLayout.WEST); 
     add(container); 
     add(forwardButton, BorderLayout.EAST); 
    } 

    // Implement the ComponentListener 

    public void componentResized(ComponentEvent e) 
    { 
     // When all components cannot be shown, add the forward button 

     int freeSpace = getSize().width - container.getPreferredSize().width; 

     if (backwardButton.isVisible()) 
      freeSpace -= backwardButton.getPreferredSize().width; 

     forwardButton.setVisible(freeSpace < 0); 

     // We have free space, redisplay removed components 

     while (freeSpace > 0 && ! removedComponents.isEmpty()) 
     { 
      if (removedComponents.size() == 1) 
       freeSpace += backwardButton.getPreferredSize().width; 

      Object o = removedComponents.get(removedComponents.size() - 1); 
      Component c = (Component)o; 
      freeSpace -= c.getSize().width; 

      if (freeSpace >= 0) 
      { 
       container.add(c, 0); 
       removedComponents.remove(removedComponents.size() - 1); 
      } 
     } 

     // Some components still not shown, add the backward button 

     backwardButton.setVisible(!removedComponents.isEmpty()); 

//  repaint(); 

    } 

    public void componentMoved(ComponentEvent e) {} 
    public void componentShown(ComponentEvent e) {} 
    public void componentHidden(ComponentEvent e) {} 

    // Implement the ActionListener 

    public void actionPerformed(ActionEvent e) 
    { 
     Object source = e.getSource(); 

     // Scroll the components in the container 

     if (source == forwardButton) 
      scrollForward(); 
     else 
      scrollBackward(); 
    } 

    /* 
    * Simulate scrolling forward 
    * by remove the first component from the container 
    */ 
    private void scrollForward() 
    { 
     if (container.getComponentCount() == 1) 
      return; 

     // Remove and save the first component 

     Component c = container.getComponent(0); 
     container.remove(c); 
     removedComponents.add(c); 

     // Allow for backwards scrolling 

     backwardButton.setVisible(true); 

     // All components are showing, hide the forward button 

     int backwardButtonWidth = backwardButton.getPreferredSize().width; 
     int containerWidth = container.getPreferredSize().width; 
     int panelWidth = getSize().width; 

     if (backwardButtonWidth + containerWidth <= panelWidth) 
      forwardButton.setVisible(false); 

     // Force a repaint of the panel 

     revalidate(); 
     repaint(); 
    } 

    /* 
    * Simulate scrolling backward 
    * by adding a removed component back to the container 
    */ 
    private void scrollBackward() 
    { 
     if (removedComponents.isEmpty()) 
      return; 

     // Add a removed component back to the container 

     Object o = removedComponents.remove(removedComponents.size() - 1); 
     Component c = (Component)o; 
     container.add(c, 0); 

     // Display scroll buttons when necessary 

     if (removedComponents.isEmpty()) 
      backwardButton.setVisible(false); 

     forwardButton.setVisible(true); 
     revalidate(); 
     repaint(); 
    } 

    private void configureButton(JButton button) 
    { 
     button.setVisible(false); 
     button.addActionListener(this); 
    } 

    private static void createAndShowGUI() 
    { 
     JToolBar toolBar = new JToolBar(); 
     toolBar.setFloatable(false); 
     toolBar.add(new JButton("one")); 
     toolBar.add(new JButton("two222222")); 
     toolBar.add(new JButton("three")); 
     toolBar.add(new JButton("four")); 
     toolBar.add(new JButton("five")); 
     toolBar.add(new JButton("six666666666")); 
     toolBar.add(new JButton("seven")); 
     toolBar.add(new JButton("eight")); 
     toolBar.add(new JButton("nine9999999")); 
     toolBar.add(new JButton("ten")); 
     ScrollContainer container = new ScrollContainer(toolBar); 

     JFrame frame = new JFrame("Scroll Container"); 
     frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     frame.add(container, BorderLayout.NORTH); 
     frame.setLocationByPlatform(true); 
     frame.pack(); 
     frame.setVisible(true); 
    } 

    public static void main(String[] args) 
    { 
     EventQueue.invokeLater(new Runnable() 
     { 
      public void run() 
      { 
       createAndShowGUI(); 
      } 
     }); 
    } 
} 

所以，你會需要修改代碼來創建一個彈出菜單包含額外的按鈕。