Chapter 17

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class Program2 {

    public static void main(String[] args) throws Exception {
        BitOutputStream output = new BitOutputStream(new File("testOutput.dat"));
        output.writeBit("010000100100001001101");
        output.close();
        System.out.println("Done");
    }

    public static class BitOutputStream {

        private FileOutputStream output;
        private int bytePosition = 0;
        private int bits; //initial bit
        //  programs statements

        // Constructor
        public BitOutputStream(File file) throws IOException {
            // one statement will do the job
            output = new FileOutputStream(file);
        }

        public void writeBit(String bitString) throws IOException {
            for (int i = 0; i < bitString.length(); i++) {
                writeBit(bitString.charAt(i));
            }
        }
 
        public void writeBit(char bit) throws IOException {
            // Program statements for this method
            bits = bits << 1;
            bytePosition++;
            if (bit == '1') {
                bits = bits | 1;
            }
            if (bytePosition == 8) {
                output.write(bits);
                bytePosition = 0; //reset position
            }
        }

        /**
         * Write the last byte and close the stream. If the last byte is not
         * full, right-shift with zeros
         */
        public void close() throws IOException {
            // Program statements for this method
            if (bytePosition > 0) {
                bits = bits << 8 - bytePosition; //fills in with 0 for incompleted byte
                output.write(bits);
            }
            output.close();
        }
    }
}