How to unzip files programmatically in Android?

The Kotlin way

//FileExt.kt

data class ZipIO (val entry: ZipEntry, val output: File)

fun File.unzip(unzipLocationRoot: File? = null) {

    val rootFolder = unzipLocationRoot ?: File(parentFile.absolutePath + File.separator + nameWithoutExtension)
    if (!rootFolder.exists()) {
       rootFolder.mkdirs()
    }

    ZipFile(this).use { zip ->
        zip
        .entries()
        .asSequence()
        .map {
            val outputFile = File(rootFolder.absolutePath + File.separator + it.name)
            ZipIO(it, outputFile)
        }
        .map {
            it.output.parentFile?.run{
                if (!exists()) mkdirs()
            }
            it
        }
        .filter { !it.entry.isDirectory }
        .forEach { (entry, output) ->
            zip.getInputStream(entry).use { input ->
                output.outputStream().use { output ->
                    input.copyTo(output)
                }
            }
        }
    }

}

Usage

val zipFile = File("path_to_your_zip_file")
file.unzip()

use the following class

    import java.io.BufferedOutputStream;
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.util.zip.ZipEntry;
    import java.util.zip.ZipInputStream;
    import android.util.Log;

    public class DecompressFast {



 private String _zipFile; 
  private String _location; 
 
  public DecompressFast(String zipFile, String location) { 
    _zipFile = zipFile; 
    _location = location; 
 
    _dirChecker(""); 
  } 
 
  public void unzip() { 
    try  { 
      FileInputStream fin = new FileInputStream(_zipFile); 
      ZipInputStream zin = new ZipInputStream(fin); 
      ZipEntry ze = null; 
      while ((ze = zin.getNextEntry()) != null) { 
        Log.v("Decompress", "Unzipping " + ze.getName()); 
 
        if(ze.isDirectory()) { 
          _dirChecker(ze.getName()); 
        } else { 
          FileOutputStream fout = new FileOutputStream(_location + ze.getName()); 
         BufferedOutputStream bufout = new BufferedOutputStream(fout);
          byte[] buffer = new byte[1024];
          int read = 0;
          while ((read = zin.read(buffer)) != -1) {
              bufout.write(buffer, 0, read);
          }

          
          
          
          bufout.close();
          
          zin.closeEntry(); 
          fout.close(); 
        } 
         
      } 
      zin.close(); 
      
      
      Log.d("Unzip", "Unzipping complete. path :  " +_location );
    } catch(Exception e) { 
      Log.e("Decompress", "unzip", e); 
      
      Log.d("Unzip", "Unzipping failed");
    } 
 
  } 
 
  private void _dirChecker(String dir) { 
    File f = new File(_location + dir); 
 
    if(!f.isDirectory()) { 
      f.mkdirs(); 
    } 
  } 


 }

How to use

 String zipFile = Environment.getExternalStorageDirectory() + "/the_raven.zip"; //your zip file location
    String unzipLocation = Environment.getExternalStorageDirectory() + "/unzippedtestNew/"; // destination folder location
  DecompressFast df= new DecompressFast(zipFile, unzipLocation);
    df.unzip();

Permissions

 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
 <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

I'm working with zip files which Java's ZipFile class isn't able to handle. Java 8 apparently can't handle compression method 12 (bzip2 I believe). After trying a number of methods including zip4j (which also fails with these particular files due to another issue), I had success with Apache's commons-compress which supports additional compression methods as mentioned here.

Note that the ZipFile class below is not the one from java.util.zip.

It's actually org.apache.commons.compress.archivers.zip.ZipFile so be careful with the imports.

try (ZipFile zipFile = new ZipFile(archiveFile)) {
    Enumeration<ZipArchiveEntry> entries = zipFile.getEntries();
    while (entries.hasMoreElements()) {
        ZipArchiveEntry entry = entries.nextElement();
        File entryDestination = new File(destination, entry.getName());
        if (entry.isDirectory()) {
            entryDestination.mkdirs();
        } else {
            entryDestination.getParentFile().mkdirs();
            try (InputStream in = zipFile.getInputStream(entry); OutputStream out = new FileOutputStream(entryDestination)) {
                IOUtils.copy(in, out);
            }
        }
    }
} catch (IOException ex) {
    log.debug("Error unzipping archive file: " + archiveFile, ex);
}

For Gradle:

compile 'org.apache.commons:commons-compress:1.18'

Based on zapl's answer, adding try() around Closeable's closes the streams automatically after use.

public static void unzip(File zipFile, File targetDirectory) {
    try (FileInputStream fis = new FileInputStream(zipFile)) {
        try (BufferedInputStream bis = new BufferedInputStream(fis)) {
            try (ZipInputStream zis = new ZipInputStream(bis)) {
                ZipEntry ze;
                int count;
                byte[] buffer = new byte[Constant.DefaultBufferSize];
                while ((ze = zis.getNextEntry()) != null) {
                    File file = new File(targetDirectory, ze.getName());
                    File dir = ze.isDirectory() ? file : file.getParentFile();
                    if (!dir.isDirectory() && !dir.mkdirs())
                        throw new FileNotFoundException("Failed to ensure directory: " + dir.getAbsolutePath());
                    if (ze.isDirectory())
                        continue;
                    try (FileOutputStream fout = new FileOutputStream(file)) {
                        while ((count = zis.read(buffer)) != -1)
                            fout.write(buffer, 0, count);
                    }
                }
            }
        }
    } catch (Exception ex) {
        //handle exception
    }
}

Using Constant.DefaultBufferSize (65536) gotten from C# .NET 4 Stream.CopyTo from Jon Skeet's answer here: https://stackoverflow.com/a/411605/1876355

I always just see posts using byte[1024] or byte[4096] buffer, never knew it can be much larger which improves performance and is still working perfectly normal.

Here is the Stream Source code: https://referencesource.microsoft.com/#mscorlib/system/io/stream.cs

//We pick a value that is the largest multiple of 4096 that is still smaller than the large object heap threshold (85K).
// The CopyTo/CopyToAsync buffer is short-lived and is likely to be collected at Gen0, and it offers a significant
// improvement in Copy performance.

private const int _DefaultCopyBufferSize = 81920;

However, I dialed it back to 65536 which is also a multiple of 4096 just to be safe.

Password Protected Zip File

if you want to compress files with password you can take a look at this library that can zip files with password easily:

Zip:

ZipArchive zipArchive = new ZipArchive();
zipArchive.zip(targetPath,destinationPath,password);

Unzip:

ZipArchive zipArchive = new ZipArchive();
zipArchive.unzip(targetPath,destinationPath,password);

Rar:

RarArchive rarArchive = new RarArchive();
rarArchive.extractArchive(file archive, file destination);

The documentation of this library is good enough, I just added a few examples from there. It's totally free and wrote specially for android.

Here is more concise version of @arsent solution:

fun File.unzip(to: File? = null) {
    val destinationDir = to ?: File(parentFile, nameWithoutExtension)
    destinationDir.mkdirs()

    ZipFile(this).use { zipFile ->
        zipFile
            .entries()
            .asSequence()
            .filter { !it.isDirectory }
            .forEach { zipEntry ->
                val currFile = File(destinationDir, zipEntry.name)
                currFile.parentFile?.mkdirs()
                zipFile.getInputStream(zipEntry).use { input ->
                    currFile.outputStream().use { output -> input.copyTo(output) }
                }
            }
    }
}