java树型结构
时间:2007-05-29 yycnet.yeah.net yyc译
使用一个JTree可以简单地像下面这样表示：add(new JTree(new Object[] {"this", "that", "other"}));这个程序显示了一个原始的树状物。树状物的API是非常巨大的，可是——当然是在Swing中的巨大。它表明我们可以做有关树状物的任何事，但更复杂的任务可能需要不少的研究和试验。幸运的是，在库中提供了一个妥协：“默认的”树状物组件，通常那是我们所需要的。因此大多数的时间我们可以利用这些组件，并且只在特殊的情况下我们需要更深入的研究和理解。下面的例子使用了“默认”的树状物组件在一个程序片中显示一个树状物。当我们按下按钮时，一个新的子树就被增加到当前选中的结点下（如果没有结点被选中，就用根结节）：
//: Trees.java
// Simple Swing tree example. Trees can be made
// vastly more complex than this.
package c13.swing;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.tree.*;
// Takes an array of Strings and makes the first
// element a node and the rest leaves:
class Branch {
DefaultMutableTreeNode r;
public Branch(String[] data) {
r = new DefaultMutableTreeNode(data[0]);
for(int i = 1; i < data.length; i++)
r.add(new DefaultMutableTreeNode(data[i]));
}
public DefaultMutableTreeNode node() {
return r;
}
}
public class Trees extends JPanel {
String[][] data = {
{ "Colors", "Red", "Blue", "Green" },
{ "Flavors", "Tart", "Sweet", "Bland" },
{ "Length", "Short", "Medium", "Long" },
{ "Volume", "High", "Medium", "Low" },
{ "Temperature", "High", "Medium", "Low" },
{ "Intensity", "High", "Medium", "Low" },
};
static int i = 0;
DefaultMutableTreeNode root, child, chosen;
JTree tree;
DefaultTreeModel model;
public Trees() {
setLayout(new BorderLayout());
root = new DefaultMutableTreeNode("root");
tree = new JTree(root);
// Add it and make it take care of scrolling:
add(new JScrollPane(tree),
BorderLayout.CENTER);
// Capture the tree''s model:
model =(DefaultTreeModel)tree.getModel();
JButton test = new JButton("Press me");
test.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e){
if(i < data.length) {
child = new Branch(data[i++]).node();
// What''s the last one you clicked?
chosen = (DefaultMutableTreeNode)
tree.getLastSelectedPathComponent();
if(chosen == null) chosen = root;
// The model will create the
// appropriate event. In response, the
// tree will update itself:
model.insertNodeInto(child, chosen, 0);
// This puts the new node on the
// currently chosen node.
}
}
});
/ |
