Android™

Compress and Decompress Hex String

See more Compression Examples

Imagine we have data represented as a hex string. This example demonstrates how to decode, compress, and re-encode to a smaller hex string representing the compressed data. An even better choice is to re-encode to a more compact encoding such as base64.

Note: This example requires Chilkat v9.5.0.66 or greater.

Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  This example assumes the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    String strHex = "54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A";

    CkCompression compress = new CkCompression();
    compress.put_Algorithm("deflate");

    CkBinData binDat = new CkBinData();
    //  Load the hex string into a BinData object.
    //  This decodes the hexidecimal. The decoded bytes will be contained in the BinData.
    binDat.AppendEncoded(strHex,"hex");

    //  Compress the BinData.
    compress.CompressBd(binDat);

    //  Get the compressed data in hex format:
    String compressedHex = binDat.getEncoded("hex");
    Log.i(TAG, "compressed hex:");
    Log.i(TAG, compressedHex);

    //  The compressed hex is: 0BC94855282CCD4CCE56482ACA2FCF5348CBAF50C82ACD2D484D51C82F4B2D522801CAE72456552AA4E4A7EBF172850C61E5BC5C00

    //  Even better, get the compressed data in base64 format:
    //  (base64url and modbase64 are other valid choices...)
    String compressedBase64 = binDat.getEncoded("base64");
    Log.i(TAG, "compressed base64:");
    Log.i(TAG, compressedBase64);

    //  The compressed base64 is: C8lIVSgszUzOVkgqyi/PU0jLr1DIKs0tSE1RyC9LLVIoAcrnJFZVKqTkp+vxcoUMYeW8XAA=

    //  Now decompress:
    binDat.Clear();
    binDat.AppendEncoded(compressedHex,"hex");
    compress.DecompressBd(binDat);

    String decompressedHex = binDat.getEncoded("hex");
    Log.i(TAG, "decompressed hex:");
    Log.i(TAG, decompressedHex);

    //  The output is the original hex string:
    //  54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A54686520717569636B2062726F776E20666F78206A756D706564206F76657220746865206C617A7920646F672E0D0A0D0A

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}