Little-endian And Big-endian

Here is  a program which converts data types written in Java (big endian) to little endian.

ProtocolBuffer converts integer to byte array and String to bytes. Using FileHandler class contents are written on a binary file.

ProtocolBuffer.java

package com;

public class ProtocolBuffer
{
    byte[] content;
    int allocated;
    int consumed;

    public ProtocolBuffer(int size)
    {
        content = new byte[size];
        allocated = size;
        consumed = 0;
    }

    boolean addInteger(int x)
    {
        content[consumed++] = (byte)(x&255);
        content[consumed++] = (byte)((x>>8)&255);
        content[consumed++] = (byte)((x>>16)&255);
        content[consumed++] = (byte)((x>>24)&255);

        return true;

    }

    boolean addString(String s)
    {
        byte[] arr = s.getBytes();
        int len = arr.length;

        for(int i = 0; i < len; i++)
        {
            content[consumed++] = arr[i];
        }
        return true;
    }

    byte[] getBytes()
    {

        return content;
    }


}

FileHandler.java to writes to and reads from binary file.

/**
 *
 */
package com;

        import java.io.RandomAccessFile;
        import java.io.File;

/**
 * @author Godel
 *
 */
public class FileHandler {

    String fname;
    int size;

    public FileHandler(String name)
    {
        fname = name;
        size = 0;
    }

    int getLength()
    {
        File file = new File(fname);
        if(file.exists())
            size =  (int)file.length();
        else
            size = 0;
        return size;
    }

    void writeBytes(byte[] content,int off,int len) throws Exception
    {
        RandomAccessFile raf = new RandomAccessFile(fname,"rw");
        raf.write(content,off,len);
        raf.close();

    }

    int readBytes(byte[] content,int off,int len) throws Exception
    {
        RandomAccessFile raf = new RandomAccessFile(fname,"rw");
        int val =  raf.read(content,off,len);
        raf.close();

        return val;
    }

}

Testing the above program ProtocolBuffer.java

package com;

public class Test {

    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub


        ProtocolBuffer a = new ProtocolBuffer(1024);
        a.addInteger(100);
        a.addInteger(5);
        a.addString("hello");
        System.out.println(a.consumed);

        FileHandler fh = new FileHandler("HandShakeProtocol4.bin");
        fh.writeBytes(a.getBytes(), 0, a.consumed);

        ProtocolBuffer b = new ProtocolBuffer(1024);
        b.addInteger(101);
        b.addInteger(28);
        for(int i = 1001;i < 1008; i++)
        {
            b.addInteger(i);

        }

        System.out.println(b.consumed);
        FileHandler fh2 = new FileHandler("HandShakeProtocol2.bin");
        fh2.writeBytes(b.getBytes(), 0, b.consumed);


    }

}

Java Program (stores data type in big endian) reads a binary file stored in little endian.

/**
 *
 */
package com;


/**
 * @author Godel
 *
 */
public class ProtocolBufferDecoder {

    byte[] content;
    int consumed;
    int allocated;

    public ProtocolBufferDecoder(byte[] b,int size)
    {
        content = b;
        consumed = 0;
        allocated = size;
    }

    int getInteger()
    {
        int x = (content[consumed++] & 0xFF) |
                ((content[consumed++] & 0xFF) << 8) |
                ((content[consumed++] & 0xFF) << 16) |
                ((content[consumed++] & 0xFF) << 24);

        return x;

    }

    String getString()
    {
        int size = allocated - consumed;
        byte[] arr = new byte[size];
        int j = 0;
        for(int i = consumed; i < allocated; i++)
        {
            arr[j] = content[consumed++];
            j++;
        }
        String s = new String(arr);
        return s;
    }



}

/**
 *
 */
package com;

        import java.io.RandomAccessFile;
        import java.io.File;

/**
 * @author Godel
 *
 */
public class FileHandler {

    String fname;
    int size;

    public FileHandler(String name)
    {
        fname = name;
        size = 0;
    }

    int getLength()
    {
        File file = new File(fname);
        if(file.exists())
            size =  (int)file.length();
        else
            size = 0;
        return size;
    }

    void writeBytes(byte[] content,int off,int len) throws Exception
    {
        RandomAccessFile raf = new RandomAccessFile(fname,"rw");
        raf.write(content,off,len);
        raf.close();

    }

    int readBytes(byte[] content,int off,int len) throws Exception
    {
        RandomAccessFile raf = new RandomAccessFile(fname,"rw");
        int val =  raf.read(content,off,len);
        raf.close();

        return val;
    }

}

package com;

public class Test {

    /**
     * @param args
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        // TODO Auto-generated method stub


        ProtocolBuffer a = new ProtocolBuffer(1024);
        a.addInteger(100);
        a.addInteger(5);
        a.addString("elloo");

        System.out.println(a.consumed);

        FileHandler handler = new FileHandler("HandShakeProtocol3.bin");

        handler.writeBytes(a.getBytes(), 0, a.consumed);
        int len = handler.getLength();
        System.out.println(len);
        byte[] b = new byte[1024];
        int num = handler.readBytes(b, 0, len);

        ProtocolBufferDecoder decode = new ProtocolBufferDecoder(b, num);
        System.out.println("Integer value:"+decode.getInteger());
        System.out.println("Integer value:"+decode.getInteger());
        System.out.println("Integer value:"+decode.getString());


    }

}