Java IO.pdf - Nguyen Dang Binh

13.2.2 Displaying File Choosers
Java I/O
Although JFileChooser is a component, not a window, you usually want to display a modal
dialog containing a JFileChooser component that asks the user to save or open a file. There
are two methods that do this without requiring you to construct a dialog or frame explicitly:
public int showOpenDialog(Component parent)
public int showSaveDialog(Component parent)
Although one method is for saving and one is for opening, you use them the same way. Both
of these methods display a modal dialog. This dialog will block input to all of the
application's windows and will block the current thread until the user either selects a file or
cancels the dialog. If the user did choose a file, both these methods return
JFileChooser.APPROVE_OPTION. If the user did not choose a file, both these methods return
JFileChooser.CANCEL_OPTION.
13.2.3 Getting the User's Selection
If showOpenDialog() or showSaveDialog() returns JFileChooser.APPROVE_OPTION, the
getSelectedFile() method returns a File object pointing to the file the user chose;
otherwise, it returns null:
public File getSelectedFile()
If the file chooser allows multiple selections, getSelectedFiles()returns an array of all the
files the user chose:
public File[] getSelectedFiles()
You can get a File object for the directory in which the selected file lives by calling
getCurrentDirectory():
public File getCurrentDirectory()
Example 13.4 is a program that uses JFileChooser to ask the user to select a file and then
prints the file's contents on System.out. This example is essentially the same as Example
13.1, except that it uses JFileChooser instead of FileDialog.
Example 13.4. JFileTyper
import java.io.*;
import javax.swing.*;
import com.macfaq.io.*;
public class JFileTyper {
public static void main(String[] args) {
JFileChooser fc = new JFileChooser();
int result = fc.showOpenDialog(new JFrame());
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