功能：實現創建一個樹形菜單
說明：創建樹形菜單結構與創建菜單欄類似，是按層次與模型創建的。
通過DefaultMutableTreeNode類創建根節點、子節點和孫節點對象，再通過DefaultTreeModel
類利用根節點創建樹模型對象，然后通過treeModel.insertNodeInto方法將節點對象插入樹模型中。
效果圖：
代碼：
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import java.awt.*; import javax.swing.*; import javax.swing.tree.*; import javax.swing.event.*; public class Tree extends JFrame implements TreeSelectionListener { private JLabel label; public Tree() { super("樹形菜單"); setSize(400,400); Container container = getContentPane(); //創建根節點和子節點 DefaultMutableTreeNode root = new DefaultMutableTreeNode("文本編輯器"); DefaultMutableTreeNode node1 = new DefaultMutableTreeNode("文件"); DefaultMutableTreeNode node2 = new DefaultMutableTreeNode("編輯"); //利用根節點創建TreeModel DefaultTreeModel treeModel = new DefaultTreeModel(root); //插入子節點node1,node2 treeModel.insertNodeInto(node1,root,root.getChildCount()); treeModel.insertNodeInto(node2,root,root.getChildCount()); //創建節點node1的子節點并插入 DefaultMutableTreeNode leafnode = new DefaultMutableTreeNode("打開"); treeModel.insertNodeInto(leafnode,node1,node1.getChildCount()); leafnode = new DefaultMutableTreeNode("保存"); treeModel.insertNodeInto(leafnode,node1,node1.getChildCount()); leafnode = new DefaultMutableTreeNode("另存為"); treeModel.insertNodeInto(leafnode,node1,node1.getChildCount()); leafnode = new DefaultMutableTreeNode("關閉"); treeModel.insertNodeInto(leafnode,node1,node1.getChildCount()); //創建節點node2的子節點并插入 leafnode = new DefaultMutableTreeNode("剪切"); treeModel.insertNodeInto(leafnode,node2,node2.getChildCount()); leafnode = new DefaultMutableTreeNode("復制"); treeModel.insertNodeInto(leafnode,node2,node2.getChildCount()); leafnode = new DefaultMutableTreeNode("粘貼"); treeModel.insertNodeInto(leafnode,node2,node2.getChildCount()); //創建樹對象 JTree tree = new JTree(treeModel); //設置Tree的選擇為一次只能選擇一個節點 tree.getSelectionModel().setSelectionMode( TreeSelectionModel.SINGLE_TREE_SELECTION); //注冊監聽器 tree.addTreeSelectionListener(this); tree.setRowHeight(20); //創建節點繪制對象 DefaultTreeCellRenderer cellRenderer = (DefaultTreeCellRenderer)tree.getCellRenderer(); //設置字體 cellRenderer.setFont(new Font("Serif",Font.PLAIN,14)); cellRenderer.setBackgroundNonSelectionColor(Color.white); cellRenderer.setBackgroundSelectionColor(Color.yellow); cellRenderer.setBorderSelectionColor(Color.red); //設置選或不選時，文字的變化顏色 cellRenderer.setTextNonSelectionColor(Color.black); cellRenderer.setTextSelectionColor(Color.blue); //把樹對象添加到內容面板 container.add(new JScrollPane(tree)); //創建標簽 label = new JLabel("你當前選擇的節點為：",JLabel.CENTER); label.setFont(new Font("Serif",Font.PLAIN,14)); container.add(label,BorderLayout.SOUTH); setVisible(true); //設置可見 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //設置窗口關閉動作 } //處理TreeSelectionEvent事件 public void valueChanged(TreeSelectionEvent event) { JTree tree = (JTree)event.getSource(); //獲取目前選取的節點 DefaultMutableTreeNode selectionNode = (DefaultMutableTreeNode)tree.getLastSelectedPathComponent(); String nodeName = selectionNode.toString(); label.setText("你當前選取的節點為： "+nodeName); } public static void main(String args[]) { Tree d = new Tree(); } } |
本文按層次與模型創建的樹形菜單，與創建菜單欄類似，不知道小伙伴們有沒有掌握吶？
