Android licensing Tutorial - Final step

Question

My app is ready for submission now but I have recently learnt about Licensing.

I have found a step by step by tutorial online: http://twistbyte.com/tutorial/using-the-android-licensing-service-step-by-step

I have imported the Licensing library into Eclipse and created the LicenseCheckActivity class as described in the tutorial.

I am on the final step of the tutorial, point number 7. The tutorial says my class should extend LicenseCheckActivity. However, the class in which I would like to check for licensing already extends Activity.

How can I use the checkLicense() method from my LicenseCheckActivity class?

Here is my code:

protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.splash);

    // Check the license
    LicenseCheckActivity  l = new LicenseCheckActivity();
    checkLicense();

This gives me the following error:

Cannot instantiate the type LicenseCheckActivity

Here is my LicenseCheckActivity class

public abstract class LicenseCheckActivity extends Activity {

static boolean licensed = true;
static boolean didCheck = false;
static boolean checkingLicense = false;
static final String BASE64_PUBLIC_KEY = "MY BASE KEY";

LicenseCheckerCallback mLicenseCheckerCallback;
LicenseChecker mChecker;

Handler mHandler;

SharedPreferences prefs;

// REPLACE WITH YOUR OWN SALT , THIS IS FROM EXAMPLE
private static final byte[] SALT = new byte[] { -46, 65, 30, -128, -103,
        -57, 74, -64, 51, 88, -95, -45, 77, -117, -36, -113, -11, 32, -64,
        89 };

private void displayResult(final String result) {
    mHandler.post(new Runnable() {
        public void run() {

            setProgressBarIndeterminateVisibility(false);

        }
    });
}

protected void doCheck() {

    didCheck = false;
    checkingLicense = true;
    setProgressBarIndeterminateVisibility(true);

    mChecker.checkAccess(mLicenseCheckerCallback);
}

protected void checkLicense() {

    Log.i("LICENSE", "checkLicense");
    mHandler = new Handler();

    // Try to use more data here. ANDROID_ID is a single point of attack.
    String deviceId = Settings.Secure.getString(getContentResolver(),
            Settings.Secure.ANDROID_ID);

    // Library calls this when it's done.
    mLicenseCheckerCallback = new MyLicenseCheckerCallback();
    // Construct the LicenseChecker with a policy.
    mChecker = new LicenseChecker(this, new ServerManagedPolicy(this,
            new AESObfuscator(SALT, getPackageName(), deviceId)),
            BASE64_PUBLIC_KEY);

    // mChecker = new LicenseChecker(
    // this, new StrictPolicy(),
    // BASE64_PUBLIC_KEY);

    doCheck();
}

protected class MyLicenseCheckerCallback implements LicenseCheckerCallback {

    public void allow() {
        Log.i("LICENSE", "allow");
        if (isFinishing()) {
            // Don't update UI if Activity is finishing.
            return;
        }
        // Should allow user access.
        displayResult(getString(R.string.allow));
        licensed = true;
        checkingLicense = false;
        didCheck = true;

    }

    public void dontAllow() {
        Log.i("LICENSE", "dontAllow");
        if (isFinishing()) {
            // Don't update UI if Activity is finishing.
            return;
        }
        displayResult(getString(R.string.dont_allow));
        licensed = false;
        // Should not allow access. In most cases, the app should assume
        // the user has access unless it encounters this. If it does,
        // the app should inform the user of their unlicensed ways
        // and then either shut down the app or limit the user to a
        // restricted set of features.
        // In this example, we show a dialog that takes the user to Market.
        checkingLicense = false;
        didCheck = true;

        showDialog(0);
    }

    public void applicationError(int errorCode) {
        Log.i("LICENSE", "error: " + errorCode);
        if (isFinishing()) {
            // Don't update UI if Activity is finishing.
            return;
        }
        licensed = false;
        // This is a polite way of saying the developer made a mistake
        // while setting up or calling the license checker library.
        // Please examine the error code and fix the error.
        String result = String.format(
                getString(R.string.application_error), errorCode);
        checkingLicense = false;
        didCheck = true;

        displayResult(result);
        // showDialog(0);
    }

    public void allow(int reason) {
        // TODO Auto-generated method stub

    }

    public void dontAllow(int reason) {
        // TODO Auto-generated method stub

    }

}

protected Dialog onCreateDialog(int id) {
    // We have only one dialog.
    return new AlertDialog.Builder(this)
            .setTitle(R.string.unlicensed_dialog_title)
            .setMessage(R.string.unlicensed_dialog_body)
            .setPositiveButton(R.string.buy_button,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog,
                                int which) {
                            Intent marketIntent = new Intent(
                                    Intent.ACTION_VIEW,
                                    Uri.parse("http://market.android.com/details?id="
                                            + getPackageName()));
                            startActivity(marketIntent);
                            finish();
                        }
                    })
            .setNegativeButton(R.string.quit_button,
                    new DialogInterface.OnClickListener() {
                        public void onClick(DialogInterface dialog,
                                int which) {
                            finish();
                        }
                    })

            .setCancelable(false)
            .setOnKeyListener(new DialogInterface.OnKeyListener() {
                public boolean onKey(DialogInterface dialogInterface,
                        int i, KeyEvent keyEvent) {
                    Log.i("License", "Key Listener");
                    finish();
                    return true;
                }
            }).create();

}

@Override
protected void onDestroy() {
    super.onDestroy();
    if (mChecker != null) {
        Log.i("LIcense", "distroy checker");
        mChecker.onDestroy();
    }
}

}

Answer 1

You are getting that error because you are trying to

 // Check the license
LicenseCheckActivity  l = new LicenseCheckActivity();

Instance an activity. You never do this! Always use the ActivityManager and Intents to start activities and pass information between them.

The solution :

Since you want your start class to continue extending Activity and cannot have it extend LicenseCheckActivity the only other suggestion would be to move the code in your start class.

Ex:

Take all the code from your LicenseCheckActivity and move it into your MainActivity class and then you can call checkLicense() in the onCreate method of your MainActivity

Answer 2

The tutorial states to extend your Activity with LicenseCheckActivity.

Example:

class ExampleActivity extends LicenseCheckActivity{
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.main);

        Toast.makeText(this, "Checking Application License", Toast.LENGTH_SHORT).show();
        // Check the license
        checkLicense();
    }
}

Because LicenseCheckActivity extends Activity, your class ExampleActivity will still inherit your Activity methods if you extend it with LicenseCheckActivity.

If you need your ExampleActivity class to extend ListActivity, then you could have LicenseCheckActivity extend ListActivity instead of activity.