public class FileClassDemo
1: //FileClassDemo.java
2: //Demonstrates use of the class File with text files.
3: //
4: import java.io.File;
5: import java.io.BufferedReader;
6: import java.io.FileReader;
7: import java.io.IOException;
8: import java.util.Scanner;
9:
10: public class FileClassDemo
11: {
12: public static void main(String[] args)
13: {
14: String name = null;
15: System.out.print("I will show you the first line ");
16: System.out.println("in a text file you name.");
17: System.out.println("The file must contain one or more lines.");
18: System.out.print("Enter file name: ");
19: Scanner keyboard = new Scanner(System.in);
20:
21: name = keyboard.nextLine();
22: File fileObject = new File(name);
23:
24: while ( (!fileObject.exists()) || (!fileObject.canRead()) )
25: {
26: if (!fileObject.exists())
27: System.out.println("No such file.");
28: else // ! fileObject.canRead()
29: System.out.println("That file is not readable.");
30: System.out.print("Enter file name again: ");
31: name = keyboard.nextLine();
32: fileObject = new File(name);
33: }
34: try
35: {
36: BufferedReader fileInput = new BufferedReader(new FileReader(name));
37: System.out.println("The first line in the file is:");
38: String firstLine = fileInput.readLine( );
39: System.out.println(firstLine);
40: fileInput.close();
41: }
42: catch(IOException e)
43: {
44: System.out.println("Problem reading from file.");
45: }
46: }
47: }
48: