1. September 9, 2008
Lecture 5 – More IO

2. Alternatives Given: FileReader myFreader; One way Another way
myFreader = new FileReader(“MyFile.txt”);
Another way
String fileName;
fileName = “MyFile.txt”;
myFreader = new FileReader(fileName);

3. Alternatives Scanner fileScanner;
fileScanner = new Scanner (new File (“a.txt”));

4. Alternatives Scanner fileScanner; String fileName; fileName = “a.txt”;
fileScanner = new Scanner (new File (fileName));

5. Alternatives Scanner fileScanner; File myFile; String fileName;
fileName = “a.txt” // get from user
myFile = new File (fileName);
fileScanner = new Scanner (myFile);

6. Alternatives FileWriter fwriter; fwriter = new FileWriter (“b.txt”);
String fileName;
fileName = “b.txt”;
Fwriter = new FileWriter (fileName);

7. Alternatives PrintWriter myPrinter;
myPrinter = new PrintWriter (new FileWriter (“b.txt”));

8. Example
import java.util.Scanner; public class Test { public static void main (String args []) { int number; Scanner keyboard; keyboard = new Scanner (System.in); System.out.println (" Hello "); System.out.println (" Please enter an integer and hit return "); while ( keyboard.hasNext()) { number = keyboard.nextInt (); System.out.println (" You entered " + number); } System.out.println (" Goodbye "); } }

9. Windows Screen Shot U:\Web\CS239\Lectures\Lecture5>java Test Hello
Please enter an integer and hit return 65
You entered 65 32
You entered 32
-235
You entered -235 ^Z
Goodbye ^D
Exception in thread "main" java.util.InputMismatchException
at java.util.Scanner.throwFor(Unknown Source)
at java.util.Scanner.next(Unknown Source)
at java.util.Scanner.nextInt(Unknown Source)
at Test.main(Test.java:14) 53
You entered 53
U:\Web\CS239\Lectures\Lecture5>

10. Alternatives PrintWriter myPrinter; FileWriter myWriter;
myWriter = new FileWriter (“b.txt”);
myPrinter = new PrintWriter (myWriter);

11. Alternatives PrintWriter myPrinter; FileWriter myWriter;
String fileName;
fileName = “b.txt”;
myWriter = new FileWriter (fileName);
myPrinter = new PrintWriter (myWriter);

12. Alternatives End of file character Unix Windows <ctrl-d>
<ctrl-z>