如何实现listener？

Question

我有一些动态的树。现在我需要实现一些功能，每次单击节点时都会发生这些功能。(我的意思是只在节点上点击一次，这“使它变成蓝色”)

**EDIT2：**我使用的是beanTreeView和openide包

如何实现此操作的listener？

编辑添加的伪代码

public class MyNode extends AbstractNode{ //openide package
   private String name;

   public MyNode(String nameOfNode){
       super (new Children.LEAF);
       name = nameOfNode;
   }
   ....
   ....
}

public class IWantNameOfSelectedNode extends JPanel{   
    private JLabel jLnameOfNode;

   public IWantNameOfSelectedNode(){
       jLnameOfNode.setText("wiating for node selection");
   }

现在，我需要将所选节点的名称放到jLabel中，并在每次节点选择发生变化时更改它。

Answer 1

假设您使用的是Swing JTree类，则应该定义一个TreeSelectionListener并将其添加到底层TreeModel中。如果您希望使用ActionListener，则需要编写一些适配器代码来将TreeSelectionEvent转换为ActionEvent(尽管这实际上是毫无意义的)。

示例

/**
 * Adapter class responsible for translating TreeSelectionEvents into
 * ActionEvents.
 */
public class TreeSelectionAdapter implements TreeSelectionListener {
  private final AtomicInteger nextId = new AtomicInteger(0);
  // Prefer CopyOnWriteArrayList to avoid ConcurrentModificationException if an
  // ActionListener removes itself as a listener during notification.
  private final CopyOnWriteArrayList<ActionListener> listeners;

  public TreeSelectionAdapter() {
    this.listeners = new CopyOnWriteArrayList<ActionListener();
  }

  public void addActionListener(ActionListener l) {
    this.listeners.add(l);
  }

  public void removeActionListener(ActionListener l) {
    this.listeners.remove(l);
  }

  public void valueChanged(TreeSelectionEvent evt) {
    // Create new ActionEvent which corresponds to incoming TreeSelectionEvent
    // and notify registered ActionListeners.
    ActionEvent aEvt = new ActionEvent(evt.getSource(),
      nextId.getAndIncrement(), "selectionChanged");

    for (ActionListener listener : listeners) {
      listener.actionPerformed(listener);
    }
  }
}

TreeNode rootNode = createTreeModel(); // Create custom model
JTree tree = new JTree(rootNode); // Install model into JTree.

// Add adapter listener to underlying selection model.
tree.getSelectionModel().addTreeSelectionListener(adapter);

// Register ActionListener with adapter listener.
adapter.addActionListener(new ActionListener() {
  public void actionPerformed(ActionEvent evt) {
    System.err.println("Selection has changed in some way!");
  }
});

Answer 2

我假设它是一棵摇摆树。您可以通过使用CustomRenderer组件或TreeSelectionListener接口来实现这一点。

这个link有一个关于如何改变图标，背景等的高级例子的教程。你需要的是一个比这个简单得多的版本。

您将感兴趣的代码是

public Component getTreeCellRendererComponent( JTree tree,
                    Object value, boolean bSelected, boolean bExpanded,
                            boolean bLeaf, int iRow, boolean bHasFocus )
    {
        // Find out which node we are rendering and get its text
        DefaultMutableTreeNode node = (DefaultMutableTreeNode)value;
        String  labelText = (String)node.getUserObject();

        this.bSelected = bSelected;

        // Set the correct foreground color
        if( !bSelected )
            setForeground( Color.black );
        else
            setForeground( Color.white );
            ....
    }