File I/O - Absolute Java - page 628

Display 10.19 Binary File I/O of Objects (part 1 of 2)

1 import java.io.ObjectOutputStream;
2 import java.io.FileOutputStream;
3 import java.io.ObjectInputStream;
4 import java.io.FileInputStream;
5 import java.io.IOException;
6 import java.io.FileNotFoundException;

7 /**
8 Demonstrates binary file I/O of serializable class objects.
9 */
10 public class ObjectIODemo
11 {
12 public static void main(String[] args)
13 {
14 try
15 {
16 ObjectOutputStream outputStream =
17 new ObjectOutputStream( new FileOutputStream("datafile"));

18 SomeClass oneObject = new SomeClass(1, 'A');
19 SomeClass anotherObject = new SomeClass(42, 'Z');

20 outputStream.writeObject(oneObject);
21 outputStream.writeObject(anotherObject);

22 outputStream.close();

23 System.out.println("Data sent to file.");
24 }
25 catch (IOException e)
26 {
27 System.out.println("Problem with file output.");
28

}

29 System.out.println(
30 "Now let's reopen the file and display the data.");
31 try
32 {
33 ObjectInputStream inputStream =
34

new ObjectInputStream( new FileInputStream("datafile"));

Notice the type casts.

35 SomeClass readOne = (SomeClass)inputStream.readObject( );
36 SomeClass readTwo = (SomeClass)inputStream.readObject( );

37 System.out.println("The following were read from the file:");
38 System.out.println(readOne);
39 System.out.println(readTwo);
40 }
41 catch (FileNotFoundException e)
42 {
43 System.out.println("Cannot find datafile.");
44 }