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问题：当向 JTree 添加键绑定时，为什么我必须将每个动作都设为自己的类？ 为什么我不能让每个动作都使用一个动作类？ 为了理解我的问题/问题，让我先解释一下我下面的问题的简短自包含示例。

addKeyBindings(JTree tree) has the following 2 lines commented out. 
//Action addsiblingnodeaction = new RightClickNodeAction("Add SiblingNode");
//Action addchildnodeaction = new RightClickNodeAction("Add ChildNode");
/*These use 1 action class, to do 2 different actions. (I want this because I 
find the code to be less verbose)
(They're commented out because they don't work for keybindings)
(The reason I ask question, is because they DO work for JPopupMenu)*/

真正的问题是为什么上面的//注释掉的代码//不适用于键绑定？（在我的示例中，我包含了一个 JPopupMenu，以表明上述注释掉的代码适用于 JPopupMenu，并且在我看来也应该适用于键绑定）（我能够使键绑定工作的唯一方法是为每个动作，您可以在下面的示例代码中看到）

import java.awt.event.ActionEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFrame;
import javax.swing.JPopupMenu;
import javax.swing.JTree;
import javax.swing.KeyStroke;

public class StackExchangeQuestion2 {
     public static void main(String[] args){
     StackExchangeQuestion2 workaround = new StackExchangeQuestion2();
     //workaround = compiler didn't like me throwing constructor code in main
     }//end main

StackExchangeQuestion2(){
     JTree tree = new JTree();   
     initRightClickMenu(tree);//purpose of existance is to show Action Code is accurate
     addKeyBindings(tree);

     JFrame window = new JFrame();
     window.getRootPane().setContentPane(tree);
     window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     window.setTitle("Stack Exchange Question");
     window.setSize(400,500);//variable parameters would be best
     window.setVisible(true);           
     }//constructor

private void initRightClickMenu(JTree tree){
     JPopupMenu rightclickmenu = new JPopupMenu();   
     Action addsiblingnodeaction = new RightClickNodeAction("Add SiblingNode");
     Action addchildnodeaction = new RightClickNodeAction("Add ChildNode");
     rightclickmenu.add(addsiblingnodeaction);
     rightclickmenu.add(addchildnodeaction);
     tree.setComponentPopupMenu(rightclickmenu);        
}

private void addSiblingNode(){
System.out.println("sibling node added");}
private void addChildNode(){
System.out.println("child node added");}     


private void addKeyBindings(JTree tree){
 //Action addsiblingnodeaction = new RightClickNodeAction("Add SiblingNode");
 Action addsiblingnodeaction = new AddSiblingNodeAction("Add SiblingNode");
    tree.getActionMap().put("Add SiblingNode", addsiblingnodeaction);
    tree.getInputMap().put(KeyStroke.getKeyStroke("ENTER"), "Add SiblingNode");    
 //Action addchildnodeaction = new RightClickNodeAction("Add ChildNode");
 Action addchildnodeaction = new AddChildNodeAction("Add ChildNode");    
    tree.getActionMap().put("Add ChildNode", addchildnodeaction);
    tree.getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "Add ChildNode");
}//end addKeyBindins    

private class AddSiblingNodeAction extends AbstractAction{      
    AddSiblingNodeAction(String name){super(name);}
    public void actionPerformed(ActionEvent ae) {    addSiblingNode();   }}

private class AddChildNodeAction extends AbstractAction{      
    AddChildNodeAction(String name){super(name);}
    public void actionPerformed(ActionEvent ae) {    addChildNode();     }}    

private class RightClickNodeAction extends AbstractAction{      
    RightClickNodeAction(String name){super(name);}
    public void actionPerformed(ActionEvent ae) {
    if(ae.getActionCommand().equals("Add SiblingNode"))addSiblingNode();
    if(ae.getActionCommand().equals("Add ChildNode"))addChildNode();     }}
}//end class
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1 回答 1

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答：因为我做错了，我不会被迫以一种方式去做。

private class RightClickNodeAction extends AbstractAction{      
    RightClickNodeAction(String name){super(name);
    putValue(ACTION_COMMAND_KEY, name); 
    }//end constructor
public void actionPerformed(ActionEvent ae) {
   //System.out.println("Action Command is: "+ae.getActionCommand());
   //the above comment verified it worked as expected + testing
if(ae.getActionCommand().equals("Add SiblingNode"))addSiblingNode();
if(ae.getActionCommand().equals("Add ChildNode"))addChildNode();     }}
于 2013-07-24T06:00:24.313 回答