Binary02.java

/*
    Binary02.java
    David Klick
    2005-01-26

Writes and then reads binary data in a file using a
    class for the record to make life easier.
*/

import java.io.*;

class MyRecord {
    public int n;
    public double x, y, z;
    public void write(DataOutputStream os) throws IOException {
        os.writeInt(n);
        os.writeDouble(x);
        os.writeDouble(y);
        os.writeDouble(z);
    }
    public void read(DataInputStream is) throws IOException {
        n = is.readInt();
        x = is.readDouble();
        y = is.readDouble();
        z = is.readDouble();
    }
    public String toString() {
        return "n = " + n + ", x = " + x + ", y = " + y + ", z = " + z;
    }
}

public class Binary02 {
    public static void main(String[] args) throws IOException {
        MyRecord[] rec = new MyRecord[10];
        MyRecord tmp = new MyRecord();

// initialize array of records
        for (int i=0; i<rec.length; i++) {
            rec[i] = new MyRecord();
            rec[i].n = i * 2;
            rec[i].x = i * 1.1;
            rec[i].y = i * 2.2;
            rec[i].z = 100.0 - i * 3.3;
        }

String filename = "Binary02.dat";

// write data to file
        DataOutputStream ofile = new DataOutputStream(
            new FileOutputStream(filename));
        for (int i=0; i<rec.length; i++) {
            rec[i].write(ofile);
        }
        ofile.close();

// read data from file
        DataInputStream ifile = new DataInputStream(
            new FileInputStream(filename));
        System.out.println("Data read from file:");
        for (int i=0; i<rec.length; i++) {
            tmp.read(ifile);
            System.out.println(i + ": " + tmp);
        }
        ifile.close();
    }
}