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ECE 122

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  1. ECE 122 April 14, 2005

  2. I/O stream • Java performs I/O through streams. • A stream is linked to a physical device by the Java I/O system. • All stream behave in the same manner, even if the actual physical device is different. • Same I/O classes and methods apply to any physical device. • Java.io package

  3. Byte Stream • Handling input/output of bytes • InputStream abstract class defines input • OutputStream abstract class defines output • Example: System.in (console input from keyboard) System.out (console output to the screen)

  4. Character Stream • Handling input and output of characters • Reader abstract class defines input • Writer abstract class defines output

  5. Console input using Character Streams • BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); • Str = br.readLine(); • Need to catch IOException • Demo ReadLines.java

  6. Console output using Character Streams • PrintWriter(OutputStream os, boolean flushOnNewline) • PrintWriter(System.out, true); • pw.println(something); • Demo PrintWriterDemo.java

  7. File output using FileWriter • FileWriter(String filename, boolean append) throws IOException • fw = new FileWriter(“test.txt”, false); • fw.write(string); • fw.close(); • Demo KtoD.java, a utility that convert keyboard input to disk.

  8. File Input using FileReader • FileReader(String filename) throws FileNotFoundException • FileReader fr = new FileReader(“test.txt”); • BufferedReader br = new BufferedReader(fr); • br.readLine(); • fr.close(); • Demo DtoS.java, a utility that read data from disk and print to screen

  9. One dimensional Array • We have introduced one-dimensional array in our previous lectures. • An array is a collection of variables of the same type, referred by a common name. • type array-name [] = new type[size]; • int age[] = new int[5];//declaration • age[0] = 20;//assignment • Animal animal [] = new Animal[1000];//declare • animal[0] = new Animal();//creation & assignment • Array length: age.length, animal.length

  10. Two dimensional array • int table[][] = new int[3][2];//declare • table[0][1] = 15;//assignment • Demo TwoD.java