前序遍歷，后序遍歷，廣度遍歷，深度遍歷，遍歷一級節點.以及按鈕如何響應點擊事件。
import java.awt.*;
import java.awt.event.*;
import java.util.*;
import javax.swing.*;
import javax.swing.tree.*;
public class Tree_03 extends JFrame{
private DefaultMutableTreeNode root; //定義根節點.
//主方法.
public static void main(String[] args){
//實例化本類.
Tree_03 frame=new Tree_03();
frame.setVisible(true);
}
//構造方法.
public Tree_03(){
super(); //繼承父類.
setTitle("遍歷節點方法"); //設置窗口標題.
setBounds(100,100,300,300); //設置絕對位置.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //設置窗口關閉方法.
root=new DefaultMutableTreeNode("ROOT"); //設置根節點名.
DefaultMutableTreeNode noteA=new DefaultMutableTreeNode("FirstA"); //定義及設置第一個子節點.
root.add(noteA); //將第一節點添加到樹根上.
//給noteA增加兩個子節點.
noteA.add(new DefaultMutableTreeNode("SecondAA"));
noteA.add(new DefaultMutableTreeNode("SecondAB"));
DefaultMutableTreeNode noteB=new DefaultMutableTreeNode("FirstB");//定義及設置第二個子節點.
root.add(noteB);
DefaultMutableTreeNode noteC=new DefaultMutableTreeNode("FirstC");//定義及設置第三個子節點.
root.add(noteC);
noteC.add(new DefaultMutableTreeNode("SecondCA"));//為noteC增加子節點.
DefaultMutableTreeNode noteSecondCB=new DefaultMutableTreeNode("SecondCB");//為noteC增加子節點.
noteC.add(noteSecondCB);//將noteSecondCB添加到noteC子節點下.
//給noteSecondCB增加子節點.
noteSecondCB.add(new DefaultMutableTreeNode("SecondCBA"));
noteSecondCB.add(new DefaultMutableTreeNode("SecondCBB"));
//給noteC增加SecondCC子節點.
noteC.add(new DefaultMutableTreeNode("SecondCC"));
JTree tree=new JTree(root);//根據根節點創建樹.
getContentPane().add(tree,BorderLayout.CENTER);
//開始操作節點.
//定義Panel.
final JPanel panel=new JPanel();
panel.setLayout(new GridLayout(0,1)); //設置panel為網格布局.
getContentPane().add(panel,BorderLayout.EAST); //將panel放置到窗口右邊.
final JButton button_01=new JButton("按前序遍歷節點"); //定義及設置第一個按鈕.
button_01.addActionListener(
new ButtonActionListener("按前序遍歷節點"));
panel.add(button_01); //將按鈕放置到panel里.
final JButton button_02=new JButton("按后序遍歷節點"); //定義及設置第二個按鈕.
button_02.addActionListener(
new ButtonActionListener("按后序遍歷節點"));
panel.add(button_02); //將按鈕放置到panel里.
final JButton button_03=new JButton("以廣度遍歷節點"); //定義及設置第三個按鈕.
button_03.addActionListener(
new ButtonActionListener("以廣度遍歷節點"));
panel.add(button_03); //將按鈕放置到panel里.
final JButton button_04=new JButton("以深度遍歷節點"); //定義及設置第四個按鈕.
button_04.addActionListener(
new ButtonActionListener("以深度遍歷節點"));
panel.add(button_04); //將按鈕放置到panel里.
final JButton button_05=new JButton("遍歷直屬子節點"); //定義及設置第五個按鈕.
button_05.addActionListener(
new ButtonActionListener("遍歷直屬子節點"));
panel.add(button_05); //將按鈕放置到panel里.
}
//定義按鈕點擊事件.
private class
ButtonActionListener implements ActionListener{
private String mode;//定義mode變量.
//構造方法.
public ButtonActionListener(String mode){
this.mode=mode;
}
//定義激活方法.
public void actionPerformed(ActionEvent e){
//聲明節點枚舉對象.
Enumeration<?> enumeration;
if(mode.equals("按前序遍歷節點")){
//按前序遍歷根節點.
enumeration=root.preorderEnumeration();
}else if(mode.equals("按后序遍歷節點")){
enumeration=root.postorderEnumeration();
}else if(mode.equals("以廣度遍歷節點")){
enumeration=root.breadthFirstEnumeration();
}else if(mode.equals("以深度遍歷節點")){
enumeration=root.depthFirstEnumeration();
}else{
enumeration=root.children();//遍歷該節點的所有子節點.
}
//知道了遍歷方式，開始遍歷.
while(enumeration.hasMoreElements()){ //遍歷枚舉對象.
//先定義一個節點變量.
DefaultMutableTreeNode node;
node=(DefaultMutableTreeNode) enumeration.nextElement();//將節點名稱給node.
//根據級別輸出占位符.
for(int l=0;l<node.getLevel();l++){
System.out.print("---");
}
System.out.println(node.getUserObject());//輸入節點標簽.
}
System.out.println();
System.out.println();
}
}
}
運行結果：
ROOT
---FirstA
------SecondAA
------SecondAB
---FirstB
---FirstC
------SecondCA
------SecondCB
---------SecondCBA
---------SecondCBB
------SecondCC
------SecondAA
------SecondAB
---FirstA
---FirstB
------SecondCA
---------SecondCBA
---------SecondCBB
------SecondCB
------SecondCC
---FirstC
ROOT
ROOT
---FirstA
---FirstB
---FirstC
------SecondAA
------SecondAB
------SecondCA
------SecondCB
------SecondCC
---------SecondCBA
---------SecondCBB
------SecondAA
------SecondAB
---FirstA
---FirstB
------SecondCA
---------SecondCBA
---------SecondCBB
------SecondCB
------SecondCC
---FirstC
ROOT
---FirstA
---FirstB
---FirstC