文件选择器不显示硬盘驱动器内容？

Question

我正在使用JFileChooser在Java中创建文件选择器，如下面的代码所示。我正在init()函数中创建文件选择器。当我运行GUI时，文件选择器出现但没有目录或硬盘驱动器出现，所以我可以选择我的文件。

我做错了什么？

代码

public void actionPerformed(ActionEvent ae)
{
    if(ae.getSource() == Bsearch){
            System.out.println("Button Search Pressed");
             JFileChooser chooser = new JFileChooser();// JFileChooser-Objekt for Bsearch-Button
              chooser.showDialog(null, "Search File");// Dialog zum Öffnen von Dateien anzeigen  
              Tdatei.setText(chooser.getSelectedFile().getAbsolutePath());//set File in Textfield Tdate
    }//if
}

错误

Exception in thread "AWT-EventQueue-1" java.lang.NullPointerException
at org.eclipse.paho.sample.GuiAsApplet$1.actionPerformed(GuiAsApplet.java:261)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$400(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Answer 1

您可以更改文件选择器的选择模式。

chooser.setFileSelectionMode(JFileChooser.FILES_AND_DIRECTORIES);

Oracle File Chooser tutorial