long byteSize = new File(sourceDir).length();

long Size = new File(sourceDir).length(); 
byteSize = Long.toString(Size);

public long getBytes() throws NameNotFoundException {

		Context context = MainActivity.getAppContext();

		PackageManager packageManager = context.getPackageManager();

		ApplicationInfo applicationInfo = packageManager.getApplicationInfo(

				this.getPackageName(), 0);

		String sourceDir = applicationInfo.sourceDir;

		long byteSize = new File(sourceDir).length();

		return byteSize;

	}

import java.util.Comparator;

import android.content.pm.PackageManager.NameNotFoundException;



public class AppBySizeComparator implements Comparator<App>

{

	int size;

    public int compare(App o1, App o2) {

        try {

        	size = o1.getBytes().compareTo(o2.getBytes());

		} catch (NameNotFoundException e) {

			// TODO Auto-generated catch block

			e.printStackTrace();

		}

		return size;

    }

}