Android™

Compressing StringBuilder Data Using CompressSb (Single Call and Chunked)

See more Compression Examples

This example demonstrates how to compress text stored in a StringBuilder using the CompressSb method in two ways:

1. Single-call compression, where the entire input is compressed in one operation.
2. Chunked compression, where the input is split into multiple parts and processed sequentially using the FirstChunk and LastChunk properties.

The example shows how compressed output is appended to a BinData object, and how the result can be verified by decompressing back to the original text. This is useful for both simple use cases and scenarios where data is processed incrementally (such as streaming or large inputs).

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Key Points

• CompressSb converts text to bytes using the Charset property (UTF-8 recommended).
• Compressed data is appended to a BinData object.
• When both FirstChunk and LastChunk are true, compression is done in a single call.
• For chunked processing:
  • First chunk → FirstChunk = true, LastChunk = false
  • Middle chunks → both false
  • Final chunk → LastChunk = true
• Chunked compression is useful when processing data incrementally.

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 has already been unlocked.
    //  See Global Unlock Sample for sample code.

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

    //  ================================================================
    //  1) Single-call compression (entire data in one call)
    //  ================================================================

    CkStringBuilder sb = new CkStringBuilder();
    sb.Append("The quick brown fox jumps over the lazy dog. ");
    sb.Append("This is a simple example using CompressSb.");

    CkBinData bdCompressed = new CkBinData();

    //  When both FirstChunk and LastChunk are true (the defaults),
    //  the entire compression happens in a single call.
    compress.put_FirstChunk(true);
    compress.put_LastChunk(true);

    success = compress.CompressSb(sb,bdCompressed);
    if (success == false) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    String compressedBase64 = bdCompressed.getEncoded("base64");

    Log.i(TAG, "Single-call compressed (base64):");
    Log.i(TAG, compressedBase64);

    //  ================================================================
    //  2) Chunked compression using FirstChunk / LastChunk
    //  ================================================================

    CkBinData bdChunkedOut = new CkBinData();

    //  First chunk
    compress.put_FirstChunk(true);
    compress.put_LastChunk(false);

    CkStringBuilder sbPart = new CkStringBuilder();
    sbPart.Append("The quick brown fox ");

    success = compress.CompressSb(sbPart,bdChunkedOut);
    if (success == false) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    //  Middle chunk
    compress.put_FirstChunk(false);
    compress.put_LastChunk(false);

    sbPart.Clear();
    sbPart.Append("jumps over the lazy dog. ");

    success = compress.CompressSb(sbPart,bdChunkedOut);
    if (success == false) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    //  Final chunk
    compress.put_FirstChunk(false);
    compress.put_LastChunk(true);

    sbPart.Clear();
    sbPart.Append("This is a chunked CompressSb example.");

    success = compress.CompressSb(sbPart,bdChunkedOut);
    if (success == false) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    String chunkedBase64 = bdChunkedOut.getEncoded("base64");

    Log.i(TAG, "Chunked compressed (base64):");
    Log.i(TAG, chunkedBase64);

    //  ================================================================
    //  3) Decompress to verify correctness
    //  ================================================================

    CkStringBuilder sbDecompressed = new CkStringBuilder();

    //  Decompress in a single call (entire data already assembled)
    compress.put_FirstChunk(true);
    compress.put_LastChunk(true);

    success = compress.DecompressSb(bdChunkedOut,sbDecompressed);
    if (success == false) {
        Log.i(TAG, compress.lastErrorText());
        return;
        }

    Log.i(TAG, "Decompressed text:");
    Log.i(TAG, sbDecompressed.getAsString());

  }

  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."
  }
}