ReadWriteData.java

// Write and then read back binary data.
import java.io.*;

public class ReadWriteData {
    public static void main(String[] args)
    {
        int i = 10;
        double d = 1023.56;
        boolean b = true;

        // Write some values.
        try (DataOutputStream dataOut =
                     new DataOutputStream(new FileOutputStream("testdata")))
        {
            System.out.println("Writing " + i);
            dataOut.writeInt(i);
            System.out.println("Writing " + d);
            dataOut.writeDouble(d);
            System.out.println("Writing " + b);
            dataOut.writeBoolean(b);
            System.out.println("Writing " + 12.2 * 7.4);
            dataOut.writeDouble(12.2 * 7.4);
        }
        catch(IOException exc) {
            System.out.println("Write error.");
            return;
        }
        System.out.println();

        // Now, read them back.
        try (DataInputStream dataIn =
                     new DataInputStream(new FileInputStream("testdata")))
        {
            i = dataIn.readInt();
            System.out.println("Reading " + i);
            d = dataIn.readDouble();
            System.out.println("Reading " + d);
            b = dataIn.readBoolean();
            System.out.println("Reading " + b);
            d = dataIn.readDouble();
            System.out.println("Reading " + d);
        }
        catch(IOException exc) {
            System.out.println("Read error.");
        }
    }
}