JFileChooser set directory

Question

Iam trying to set the directory which my JFileChooser should show. Iam trying to work with the method setCurrentDirectory :

public class FileChooser {
    public static void main(String[] args) {        
        JFrame jf = new JFrame();
        JFileChooser chooser = new JFileChooser();

        jf.add(chooser);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.pack();

        File file = new File("C:\\");

        if(file.exists() && chooser != null) {
            chooser.setCurrentDirectory(file);
        }
    }
}

Here is the weird part:

When I run my program everything works. But when I try to run it again, it sometimes throws a NullPointerException . This can happen after the first re-run, or it can work 10 times in a row. There is no pattern. Iam not modifying my C: directory.

This is the whole code , this is no snipped.

The full stacktrace:

Exception in thread "main" java.lang.NullPointerException
at javax.swing.plaf.basic.BasicListUI.updateLayoutState(BasicListUI.java:1368)
at javax.swing.plaf.basic.BasicListUI.maybeUpdateLayoutState(BasicListUI.java:1311)
at javax.swing.plaf.basic.BasicListUI.getCellBounds(BasicListUI.java:952)
at javax.swing.JList.getCellBounds(JList.java:1637)
at javax.swing.JList.ensureIndexIsVisible(JList.java:1149)
at sun.swing.FilePane.ensureIndexIsVisible(FilePane.java:1708)
at sun.swing.FilePane.doDirectoryChanged(FilePane.java:1631)
at sun.swing.FilePane.propertyChange(FilePane.java:1681)
at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263)
at java.awt.Component.firePropertyChange(Component.java:8434)
at javax.swing.JFileChooser.setCurrentDirectory(JFileChooser.java:598)
at filechooser.FileChooser.main(FileChooser.java:21)

When I try to set the directory via the constructor JFileChooser(String currentDirectoryPath) , everything works. Even if I try it 100 times in a row (trust me, I tried it 100 times). Code:

public class FileChooser {
    public static void main(String[] args) {        
        JFrame jf = new JFrame();
        JFileChooser chooser = new JFileChooser("C:\\");

        jf.add(chooser);
        jf.setVisible(true);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.pack();
    }
}

So there has to be something wrong with chooser.setCurrentDirectory(new File("C:\\\\")); There is no way for me to work with the constructor. I do have to set the currentDirectory.

When the Exception is thrown, getCurrentDirectory() returns C:\\ , even if my FileChooser is not showing this directory.

Does anyone have an idea whats going on here?

Answer 1

Thanks to Andrew Thompson , I got it working. I had to replace

chooser.setCurrentDirectory(file);

with

SwingUtilities.invokeLater(() -> chooser.setCurrentDirectory(new File("C:\\")));