Using this, when decompressing a file around 800mb on my nexus 7, the app slows down badly. *SOLUTION: Use asynctask*

MainActivity.java

//Called on a button click in my Main activity file

public MainActivity instance;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    instance = getInstance();
    //rest of code...
}

public MainActivity getInstance() {
    if (instance == null) {
        instance = this;
    }
    return instance;
}

try {
    new ZipTool(instance).decompress();
} catch (IOException e) {
    e.printStackTrace();
}

ZipTool.java

import android.util.Log;

import com.appsbytravis.acmusic.MainActivity;
import com.snatik.storage.Storage;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Locale;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class ZipTool {
    private final MainActivity instance;
    private int prepareAssetsProgress = 0;
    private static final int BUFFER_SIZE = 1024;
    private Storage storage;
    private String path;

    private static final String ASSET_FILE = "/music_assets.zip";
    private static final String ASSETS_PATH = "/assets/";

    public ZipTool(MainActivity instance) {
        this.instance = instance;
        storage = new Storage(instance);
        path = storage.getInternalFilesDirectory();

    }

    public void decompress() throws IOException {
        File file = storage.getFile(path.concat(ASSET_FILE));
        FileInputStream fis = new FileInputStream(file.getPath());
        ZipInputStream zis = new ZipInputStream(new BufferedInputStream(fis));
        ZipEntry entry;
        byte[] bytesIn = new byte[BUFFER_SIZE];
        while ((entry = zis.getNextEntry()) != null) {
            if (instance.isPreparing) {
                String filePath = path.concat(ASSETS_PATH).concat(entry.getName());
                long size = entry.getSize();
                if (!entry.isDirectory()) {
                    Log.d(instance.TAG, entry.getName());
                    FileOutputStream fos = new FileOutputStream(filePath);
                    BufferedOutputStream bos = new BufferedOutputStream(fos);
                    int read;
                    while ((read = zis.read(bytesIn)) != -1) {
                        bos.write(bytesIn, 0, read);
                        prepareAssetsProgress += bytesIn.length;
                        instance.bar.setProgress((int) (prepareAssetsProgress / size));
                        instance.progressTextView.setText(String.format(Locale.US, "%d%%", (int) (prepareAssetsProgress / size)));
                    }
                    fos.close();
                } else {
                    Log.d(instance.TAG, entry.getName());
                    storage.createDirectory(filePath);
                }

                zis.closeEntry();
            } else {
                break;
            }
        }
        zis.close();
    }
}