I am trying to figure out how to code a event that, if clicked in a Swing JTree and the mouse does not click anything in the tree, to get a println that says "nothing".
Say I have a tree 'info_tree' with an AWT.event.Mouwesvent as such:
private void info_treeMouseClicked(java.awt.event.MouseEvent evt) {
if(info_tree.getSelectionPath() /*something along the lines of is empty or if !info_tree.getSelectionPath().isEmpty()*/
){system.out.println("Nothing");
}else{
system.out.println("Something");
}
}
I can't find anything to compare a selectedPath or element of a tree.
You may wish to try
If (info_tree.getSelectionPath()==null)
But,then you may want to switch your output lines around. Because that as-is is a true/false condition. If false it'll goto else. That could solve it as well.
You can try this program:
import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreePath;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class JTreeGetSelectedNode extends JFrame {
public JTreeGetSelectedNode() throws HeadlessException {
initializeUI();
}
private void initializeUI() {
setSize(200, 400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DefaultMutableTreeNode root = new DefaultMutableTreeNode("Countries");
DefaultMutableTreeNode asia = new DefaultMutableTreeNode("Asia");
String[] countries = new String[] {"India", "Singapore", "Indonesia", "Vietnam"};
for (String country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
asia.add(node);
}
DefaultMutableTreeNode northAmerica = new DefaultMutableTreeNode("North America");
countries = new String[] {"United States", "Canada"};
for (String country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
northAmerica.add(node);
}
DefaultMutableTreeNode southAmerica = new DefaultMutableTreeNode("South America");
countries = new String[] {"Brazil", "Argetina", "Uruguay"};
for (String country : countries) {
DefaultMutableTreeNode node = new DefaultMutableTreeNode(country);
southAmerica.add(node);
}
DefaultMutableTreeNode europe = new DefaultMutableTreeNode("Europe");
countries = new String[] {"United Kingdom", "Germany", "Spain", "France", "Italy"};
for (String 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);
JScrollPane pane = new JScrollPane(tree);
pane.setPreferredSize(new Dimension(200, 400));
JButton button = new JButton("Get Selected");
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
Object paths = tree.getLastSelectedPathComponent();
if(paths == null){
System.out.println("nothig");
}else{
System.out.println("Something");
}
}
});
getContentPane().setLayout(new BorderLayout());
getContentPane().add(pane, BorderLayout.CENTER);
getContentPane().add(button, BorderLayout.SOUTH);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new JTreeGetSelectedNode().setVisible(true);
}
});
}
}
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