Unzip.java

package com.dc.myapplication;

import android.os.Bundle;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class MainActivity extends AppCompatActivity {

  @Override protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    File obbDir = getObbDir();
    File fileToExtract = new File(obbDir, "main.1.com.dc.android.zip");
    File extractTo = new File(Environment.getExternalStorageDirectory(), "Extracted");
    if (!extractTo.exists()) extractTo.mkdir();
    try {
      unzip(fileToExtract, extractTo);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

  public static void unzip(File zipFile, File targetDirectory) throws IOException {
    ZipInputStream zis = new ZipInputStream(new BufferedInputStream(new FileInputStream(zipFile)));
    try {
      ZipEntry ze;
      int count;
      byte[] buffer = new byte[8192];
      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;
        FileOutputStream fout = new FileOutputStream(file);
        try {
          while ((count = zis.read(buffer)) != -1) fout.write(buffer, 0, count);
        } finally {
          fout.close();
        }
            /* if time should be restored as well
            long time = ze.getTime();
            if (time > 0)
                file.setLastModified(time);
            */
      }
    } finally {
      zis.close();
    }
  }
}