import java.awt.Dimension;import java.awt.Color;import javax.swing.JFrame;import javax.swing.JPanel;import javax.swing.JScrollPane;import javax.swing.JTree;import javax.swing.BoxLayout;import javax.swing.tree.TreePath;import javax.swing.tree.DefaultMutableTreeNode;import javax.swing.tree.DefaultTreeModel;/*JTree的构造函数:JTree()JTree(Hashtable value)JTree(Object[] value)//只有这个构造函数可以创建多个根结点JTree(TreeModel newModel)JTree(TreeNode root)JTree(TreeNode root, boolean asksAllowsChildren)JTree(Vector value) */public class JTreeDemo{ public static void main (String[] args) {   //构造函数：JTree()  JTree example1 = new JTree();       //构造函数：JTree(Object[] value)  Object[] letters= {"a", "b", "c", "d", "e"};  JTree example2 = new JTree (letters);     //构造函数：JTree(TreeNode root)(TreeNode空)  //用空结点创建树  DefaultMutableTreeNode node1 = new DefaultMutableTreeNode();//定义树结点  JTree example3 = new JTree (node1);//用此树结点做参数调用 JTree的构造函数创建含有一个根结点的树     //构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)  //用一个根结点创建树  DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("Color");  JTree example4 = new JTree (node2);//结点不可以颜色,默认为白面黑字  example4.setBackground (Color.lightGray);     //构造函数：JTree(TreeNode root, boolean asksAllowsChildren)(同上,只是TreeNode又有不同)  //使用DefaultMutableTreeNode类先用一个根结点创建树，设置为可添加孩子结点,再添加孩子结点  DefaultMutableTreeNode color = new DefaultMutableTreeNode("Color", true);  DefaultMutableTreeNode gray = new DefaultMutableTreeNode ("Gray");  color.add (gray);  color.add (new DefaultMutableTreeNode ("Red"));  gray.add (new DefaultMutableTreeNode ("Lightgray"));  gray.add (new DefaultMutableTreeNode ("Darkgray"));  color.add (new DefaultMutableTreeNode ("Green"));  JTree example5 = new JTree (color);          //构造函数：JTree(TreeNode root)(同上,只是TreeNode非空)  //通过逐个添加结点创建树  DefaultMutableTreeNode biology = new DefaultMutableTreeNode ("Biology");  DefaultMutableTreeNode animal = new DefaultMutableTreeNode ("Animal");  DefaultMutableTreeNode mammal = new DefaultMutableTreeNode ("Mammal");  DefaultMutableTreeNode horse = new DefaultMutableTreeNode ("Horse");  mammal.add (horse);  animal.add (mammal);  biology.add (animal);  JTree example6 = new JTree (biology);  horse.isLeaf();  horse.isRoot();       //构造函数:JTree(TreeModel newModel)  //用DefaultMutableTreeNodel类定义一个结点再用这个结点做参数定义一个用DefaultTreeMode  //创建一个树的模型,再用JTree的构造函数创建一个树    DefaultMutableTreeNode root = new DefaultMutableTreeNode ("Root1");  DefaultMutableTreeNode child1 = new DefaultMutableTreeNode ("Child1");  DefaultMutableTreeNode child11 = new DefaultMutableTreeNode ("Child11");  DefaultMutableTreeNode child111 = new DefaultMutableTreeNode ("Child111");  root.add (child1); child1.add (child11); child11.add (child111);        DefaultTreeModel model = new DefaultTreeModel (root);    JTree example7 = new JTree (model);     JPanel panel = new JPanel();  panel.setLayout (new BoxLayout (panel, BoxLayout.X_AXIS));  panel.setPreferredSize (new Dimension (700, 400));  panel.add (new JScrollPane (example1));//JTree必须放在JScrollPane上  panel.add (new JScrollPane (example2));  panel.add (new JScrollPane (example3));  panel.add (new JScrollPane (example4));  panel.add (new JScrollPane (example5));  panel.add (new JScrollPane (example6));  panel.add (new JScrollPane (example7));       JFrame frame = new JFrame ("JTreeDemo");  frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);  frame.setContentPane (panel);  frame.pack();  frame.show(); }}

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