Blog

Json parsers online

Really useful for debugging JSON data.

http://json.parser.online.fr/
https://jsonformatter.curiousconcept.com/

October 3, 2015
Generate Java Objects from JSON

http://www.jsonschema2pojo.org/

Very useful tool when you need to fetch data from REST API with Retrofit library.

Great example how it used with RxJava: https://youtu.be/JCLZ55M2gVo?t=35m53s

October 2, 2015
Retrolambda – Backport of lambdas

Retrolambda allows to use lambda expressions on Java 7, 6 and 5.

More about Lambda Expressions

October 1, 2015
RxJava magic on Android

RxJava – a library for composing asynchronous and event-based programs by using observable sequences.

September 30, 2015

Barcode Detector – Simple example

1. Dependencies:

dependencies {
    compile 'com.android.support:appcompat-v7:23.0.1'
    compile 'com.google.android.gms:play-services:8.1.0'
}

2. Initialization code:

    private BarcodeDetector detector;
    ...
    private void initAndCheckDetector() {
        detector = new BarcodeDetector.Builder(getActivity().getApplicationContext())
                .setBarcodeFormats(Barcode.DATA_MATRIX | Barcode.QR_CODE | Barcode.EAN_13)
                .build();
        if (!detector.isOperational()) {
            Toast.makeText(getActivity().getApplicationContext(), "Could not set up the detector!", Toast.LENGTH_SHORT).show();
            detector = null;
        }
    }

Recognize Barcode:

    private void recognizeBarcode(Bitmap myBitmap ) {
        if (detector!= null) {
            Frame frame = new Frame.Builder().setBitmap(myBitmap).build();
            SparseArray<Barcode> barcodes = detector.detect(frame);
            Barcode code = barcodes.valueAt(0);
            String result = code.rawValue;
        }
    }

Barcode Detection with the Mobile Vision API

September 29, 2015

LeakCanary – SuperSonic causes an activity leak

After watching “Speed app your app” I tried to use the LeakCanary lib and I was surprised:

SuperSonic that I was using in my current project, caused an activity leak.

SuperSonic

September 28, 2015
Speed app your app

Real examples for performance issues, and how to identify them with the available tools.
http://blog.udinic.com/2015/09/15/speed-up-your-app

September 27, 2015

Software keyboard control

Add soft keyboard listener:

final View activityRootView = getWindow().getDecorView().findViewById(android.R.id.content);
        activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                int heightDiff = activityRootView.getRootView().getHeight() - activityRootView.getHeight();
                if (heightDiff > 100) { // 99% of the time the height diff will be due to a keyboard.
                    if (!isSoftKeyboardOpen) {
                        MyLogger.log(TAG, "Soft keyboard is visible");
                        isSoftKeyboardOpen = true;
                    }
                    isSoftKeyboardOpen = true;
                } else if (isSoftKeyboardOpen) {
                    MyLogger.log(TAG, "Soft keyboard invisible");
                    isSoftKeyboardOpen = false;
                    removeFocusAndSaveToDB();
                }
            }
        });

Opens soft keyboard when alert dialog shown:

alertDialog.getWindow()
    .setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE);

September 26, 2015

Oracle certification, Java SE 7 Programmer I (1Z0-803)
Useful information about this exam:
- Oracle, Java tutorial for Programmer Level I Exam: http://docs.oracle.com/javase/tutorial/extra/certification/javase-7-programmer1.html
- Sample questions: http://education.oracle.com/pls/web_prod-plq-dad/db_pages.getpage?page_id=303&p_certName=SQ1Z0_803
- Questions with detailed explanations: http://enthuware.com/
- This book really helped me pass the exam: https://www.manning.com/books/oca-java-se-7-programmer-i-certification-guide
And this is how the Java SE 7 Programmer I certification looks like:
September 25, 2015

GCM – Push notification code (php)

An example that I used for tests.

define( 'API_ACCESS_KEY', 'fill_here_your_api_access_key' ); 
$registrationIds = array("fill_here_registered_id_of_your _device"); 

$msg = array ( 
    'parameter1' =>; 'Some data that you want to send',
    'parameter2' =>; 'Some additional data...',
);

$fields = array
(
    'registration_ids'  =>; $registrationIds,
    'data'              =>; $msg
);

$headers = array
(
    'Authorization: key=' . API_ACCESS_KEY,
    'Content-Type: application/json'
);

$ch = curl_init();
curl_setopt( $ch,CURLOPT_URL, 'https://android.googleapis.com/gcm/send' );
curl_setopt( $ch,CURLOPT_POST, true );
curl_setopt( $ch,CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ) );
$result = curl_exec($ch );
curl_close( $ch );

echo $result;

September 24, 2015