For current Android application package:
public String getDataDir(Context context) throws Exception {
return context.getPackageManager().getPackageInfo(context.getPackageName(), 0).applicationInfo.dataDir;
}
For any package:
public String getAnyDataDir(Context context, String packageName) throws Exception {
return context.getPackageManager().getPackageInfo(packageName, 0).applicationInfo.dataDir;
}