Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

550 Chapter 14 Exception Handling and Text I/O
FIGURE 14.10
JFileChooser can be used to display a file dialog for opening a file.
Listing 14.16 gives a program that prompts the user to choose a file and displays its contents
on the console.
create a JFileChooser
display file chooser
check status
getSelectedFile
showOpenDialog
APPROVE_OPTION
getSelectedFile
✓Point✓ Check
LISTING 14.16
ReadFileUsingJFileChooser.java
1 import java.util.Scanner;
2 import javax.swing.JFileChooser;
3
4 public class ReadFileUsingJFileChooser {
5 public static void main(String[] args) throws Exception {
6 JFileChooser fileChooser = new JFileChooser();
7 if ( fileChooser.showOpenDialog(null)
8 == JFileChooser.APPROVE_OPTION) {
9 // Get the selected file
10 java.io.File file = fileChooser.getSelectedFile() ;
11
12 // Create a Scanner for the file
13 Scanner input = new Scanner(file);
14
15 // Read text from the file
16 while (input.hasNext()) {
17 System.out.println(input.nextLine());
18 }
19
20 // Close the file
21 input.close();
22 }
23 else {
24 System.out.println("No file selected");
25 }
26 }
27 }
The program creates a JFileChooser in line 6. The showOpenDialog(null) method displays
a dialog box, as shown in Figure 14.10. The method returns an int value, either
APPROVE_OPTION or CANCEL_OPTION, which indicates whether the Open button or the
Cancel button was clicked.
The getSelectedFile() method (line 10) returns the selected file from the file dialog
box. Line 13 creates a scanner for the file. The program continuously reads the lines from the
file and displays them to the console (lines 16–18).
14.36 How do you create a File Open dialog box? What is returned from invoking
getSelectFile() on a JFileChooser object?