Android Implementation of File Chooser Dialogue Java

Question

I have written a save text encryption tool in Java, which i want to run and share on Android, But i have problems at implementing a File Chooser Dialogue in Android. So how to convert this:

int rueckgabeWert=0;
JFileChooser chooser = new JFileChooser();
rueckgabeWert = chooser.showOpenDialog(null);
if(rueckgabeWert == JFileChooser.APPROVE_OPTION)
{
    JOptionPane.showMessageDialog(rootPane, "Successfully loaded");
}
else{
    JOptionPane.showMessageDialog(rootPane, "No file selected");
    chooser.cancelSelection();
}
rueckgabeWert=0;
FileReader f=new FileReader(chooser.getSelectedFile().getPath());
BufferedReader r =new BufferedReader(f);

Into Something which is usable in an .apk or does anyone have another suggestoin on how to get it to work on Android and make it easily shareable (one File)?

For full Source Code: http://pastebin.com/QFhvRtaq