qdil
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Huffman Compression
Is there a built in class in Java to carry out Huffman compression?
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No comment has been added lately, so it's time to clean up this TA.
I will leave a recommendation in the Cleanup topic area that this question is:
- points to girionis
Please leave any comments here within the
next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !
girionis
Cleanup Volunteer
I will leave a recommendation in the Cleanup topic area that this question is:
- points to girionis
Please leave any comments here within the
next seven days.
PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !
girionis
Cleanup Volunteer
You could try this way, using java.util.zip package:
-------huffman.java-------
import java.util.zip.Deflater;
import java.util.zip.DeflaterOutp
import java.util.zip.InflaterInpu
import java.io.ByteArrayOutputStr
import java.io.ByteArrayInputStre
public class huffman
{
private static final String INPUT = "this is the original. is this the original? this is the original!";
public static void main( String[] args ) throws Throwable
{
Deflater deflater = new Deflater();
deflater.setStrategy( Deflater.HUFFMAN_ONLY );
ByteArrayOutputStream bytes = new ByteArrayOutputStream();
DeflaterOutputStream out = new DeflaterOutputStream( bytes, deflater );
out.write( INPUT.getBytes(), 0, INPUT.length() );
out.close();
deflater.finish();
byte[] compressed = bytes.toByteArray();
System.out.println( "Input length:"+INPUT.length()+" Output length:"+compressed.length
System.out.println( "Compressed data: "+new String( compressed )+"\n-------" );
ByteArrayInputStream compressedBytes = new ByteArrayInputStream( compressed );
InflaterInputStream in = new InflaterInputStream( compressedBytes );
ByteBuffer byteBuffer = new ByteBuffer();
while (in.available()==1)
{
byteBuffer.append( (byte)in.read() );
}
in.close();
String output = new String( byteBuffer.getBytes() );
System.out.println( "Input string: "+INPUT+"\nOutput string: "+output );
}
} /* huffman */
-------huffman.java-------
-------ByteBuffer.java----
public class ByteBuffer
{
// Constants
private static final int DEFAULT_CAPACITY = 32;
// Properties
private byte[] bytes;
private int used;
// Constructor
public ByteBuffer()
{
bytes = new byte[DEFAULT_CAPACITY];
used = 0;
}
// Methods
public void append( byte b )
{
if (used < bytes.length)
{
bytes[used++] = b;
}
else
{
bytes = repack( bytes.length*2 );
append( b );
}
}
public byte[] getBytes()
{
return repack( used );
}
private byte[] repack( int newSize )
{
byte[] newBytes = new byte[newSize];
System.arraycopy( bytes, 0, newBytes, 0, Math.min( used, newSize ) );
return newBytes;
}
} /* ByteBuffer */
-------ByteBuffer.java----
I haven't tried to decompress the codes generated by some other encoder, and also if some other huffman decoder would decompress codes generated by Deflator, but if you need that, you will hopefully test and post here your results :-)
Best wishes,
</ntr> :)