datastreams.java

java tutorial.sun公司官方出品。java入门书籍。最新版

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 *
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 *     from this software without specific prior written permission.
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 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.EOFException;

public class DataStreams {
    static final String dataFile = "invoicedata";

    static final double[] prices = { 19.99, 9.99, 15.99, 3.99, 4.99 };
    static final int[] units = { 12, 8, 13, 29, 50 };
    static final String[] descs = { "Java T-shirt",
            "Java Mug",
            "Duke Juggling Dolls",
            "Java Pin",
            "Java Key Chain" };

    public static void main(String[] args) throws IOException {

 
        DataOutputStream out = null;
        
        try {
            out = new DataOutputStream(new
                    BufferedOutputStream(new FileOutputStream(dataFile)));

            for (int i = 0; i < prices.length; i ++) {
                out.writeDouble(prices[i]);
                out.writeInt(units[i]);
                out.writeUTF(descs[i]);
            }
        } finally {
            out.close();
        }

        DataInputStream in = null;
        double total = 0.0;
        try {
            in = new DataInputStream(new
                    BufferedInputStream(new FileInputStream(dataFile)));

            double price;
            int unit;
            String desc;

            try {
                while (true) {
                    price = in.readDouble();
                    unit = in.readInt();
                    desc = in.readUTF();
                    System.out.format("You ordered %d units of %s at $%.2f%n",
                            unit, desc, price);
                    total += unit * price;
                }
            } catch (EOFException e) { }
            System.out.format("For a TOTAL of: $%.2f%n", total);
        }
        finally {
            in.close();
        }
    }
}