Java如何为每个节点创建带有不同图标的JTree？
以下示例演示了如何为JTree树的每个节点创建一个具有不同图标的。
package org.nhooo.example.swing;
import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeCellRenderer;
import java.awt.*;
import java.net.URL;
public class JTreeDifferentNodeIcon extends JFrame {
public JTreeDifferentNodeIcon() throws HeadlessException {
initializeUI();
}
private void initializeUI() {
setSize(200, 400);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
DefaultMutableTreeNode root = new DefaultMutableTreeNode("Countries");
DefaultMutableTreeNode asia = new DefaultMutableTreeNode("Asia");
Country[] countries = new Country[]{
new Country("India", "/flags/in.png"),
new Country("Singapore", "/flags/sg.png"),
new Country("Indonesia", "/flags/id.png"),
new Country("Vietnam", "/flags/vn.png"),
};
for (Country country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
asia.add(node);
}
DefaultMutableTreeNode northAmerica = new DefaultMutableTreeNode("North America");
countries = new Country[]{
new Country("United States", "/flags/us.png"),
new Country("Canada", "/flags/ca.png")
};
for (Country country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
northAmerica.add(node);
}
DefaultMutableTreeNode southAmerica = new DefaultMutableTreeNode("South America");
countries = new Country[]{
new Country("Brazil", "/flags/br.png"),
new Country("Argentina", "/flags/ar.png"),
new Country("Uruguay", "/flags/uy.png")
};
for (Country country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
southAmerica.add(node);
}
DefaultMutableTreeNode europe = new DefaultMutableTreeNode("Europe");
countries = new Country[]{
new Country("United Kingdom", "/flags/gb.png"),
new Country("Germany", "/flags/de.png"),
new Country("Spain", "/flags/es.png"),
new Country("France", "/flags/fr.png"),
new Country("Italy", "/flags/it.png")
};
for (Country country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
europe.add(node);
}
root.add(asia);
root.add(northAmerica);
root.add(southAmerica);
root.add(europe);
final JTree tree = new JTree(root);
tree.setCellRenderer(new CountryTreeCellRenderer());
JScrollPane pane = new JScrollPane(tree);
pane.setPreferredSize(new Dimension(200, 400));
getContentPane().setLayout(new BorderLayout());
getContentPane().add(pane, BorderLayout.CENTER);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new JTreeDifferentNodeIcon().setVisible(true);
}
});
}
class CountryTreeCellRenderer implements TreeCellRenderer {
private JLabel label;
CountryTreeCellRenderer() {
label = new JLabel();
}
public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded,
boolean leaf, int row, boolean hasFocus) {
Object o = ((DefaultMutableTreeNode) value).getUserObject();
if (o instanceof Country) {
Country country = (Country) o;
URL imageUrl = getClass().getResource(country.getFlagIcon());
if (imageUrl != null) {
label.setIcon(new ImageIcon(imageUrl));
}
label.setText(country.getName());
} else {
label.setIcon(null);
label.setText("" + value);
}
return label;
}
}
class Country {
private String name;
private String flagIcon;
Country(String name, String flagIcon) {
this.name = name;
this.flagIcon = flagIcon;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getFlagIcon() {
return flagIcon;
}
public void setFlagIcon(String flagIcon) {
this.flagIcon = flagIcon;
}
}
}运行上面程序
FamFamFam标志图标提供的标志图标。