Drag and Swipe with RecyclerView

Here is good tutorial.

Drag and Swipe with RecyclerView

Working with images

If you're working with images (as background for example) you could face with big sizes of files.
Something like JPEG file 1280X1920px could take about 0.5 - 1.0M depending of content.
And it increases APK size!
Very nice solution I found is WebP.
You can download one of converters here: xnconvert

In my case I have following result: 789kb -> 96 kb (80% quality)

TODO: Implement Realm

realm.io

Market coverage by Android app with minSdkVersion

According google report July 6, 2017. we have following situation:

Version	Codename	API	Distribution	Coverage by app with minSdkVersion
2.3.3 - 2.3.7	Gingerbread	10	0.70%	100.00%
4.0.3 - 4.0.4	Ice Cream Sandwich	15	0.70%	99.30%
4.1.x	Jelly Bean	16	2.80%	98.60%
4.2.x		17	4.10%	95.80%
4.3		18	1.20%	91.70%
4.4	KitKat	19	17.10%	90.50%
5	Lollipop	21	7.80%	73.40%
5.1		22	22.30%	65.60%
6	Marshmallow	23	31.80%	43.30%
7	Nougat	24	10.60%	11.50%
7.1		25	0.90%	0.90%

So, if you're developing with minSdkVersion=21 you cover about 3/4 of market.

And if you're developing with minSdkVersion=19 you cover more than 9/10 of market. 

MBaaS

Some useful links (Russian)

How to intercept event Soft keyboard shown/hidden

This is solution that is composed of code from SO and my enhancement to support various API levels.
Inspired by SO post http://stackoverflow.com/questions/2150078/how-to-check-visibility-of-software-keyboard-in-android

Updated 1/24/2017

Updated 15 Apr. 2017
I hope, this solution is final.

Preparation class:

package my.package.utils;

import android.graphics.Rect;
import android.os.Build;
import android.view.View;
import android.view.ViewTreeObserver;

import java.util.LinkedList;
import java.util.List;

public class SoftKeyboardStateWatcher
        implements ViewTreeObserver.OnGlobalLayoutListener {

    public void onStart() {
        isSoftKeyboardOpened = false;
    }

    public interface SoftKeyboardStateListener {
        void onSoftKeyboardOpened(int keyboardHeightInPx);

        void onSoftKeyboardClosed();

    }

    private SoftKeyboardStateListener listener;

    private final View activityRootView;
    private boolean isSoftKeyboardOpened;
    private int resize;
    private int mKeyboardHeight;

    public SoftKeyboardStateWatcher(
            View activityRootView,
            SoftKeyboardStateListener listener
    ) {
        this(activityRootView, false);
        this.listener = listener;
    }

    private SoftKeyboardStateWatcher(
            View activityRootView,
            boolean isSoftKeyboardOpened
    ) {
        this.activityRootView = activityRootView;
        this.isSoftKeyboardOpened = isSoftKeyboardOpened;
        activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(this);
    }

    @Override    public void onGlobalLayout() {
        Rect r = new Rect();
        activityRootView.getWindowVisibleDisplayFrame(r);
        int heightDiff = activityRootView.getRootView().getHeight() - (r.bottom - r.top);
        int correction = r.top;
        if (!isSoftKeyboardOpened && heightDiff > correction &&
                heightDiff > getStatusBarHeight() + getNavBarHeight()) {
            isSoftKeyboardOpened = true;
            notifyOnSoftKeyboardOpened(heightDiff, correction);
        } else {
            if (isSoftKeyboardOpened && heightDiff <= correction) {
                isSoftKeyboardOpened = false;
                notifyOnSoftKeyboardClosed();
            }else{
                if (!isSoftKeyboardOpened) return;
                if (mKeyboardHeight == heightDiff - correction) return;
                //Keyboard height has changed
            }
        }
    }

    private void notifyOnSoftKeyboardOpened(int keyboardHeightInPx, int correction) {
        if (listener == null) return;
        mKeyboardHeight = keyboardHeightInPx - correction;
        listener.onSoftKeyboardOpened(keyboardHeightInPx);
    }

    private void notifyOnSoftKeyboardClosed() {
        if (listener == null) return;
        listener.onSoftKeyboardClosed();
    }

    public void removeSoftKeyboardStateListener() {
        listener = null;
    }

    private int getStatusBarHeight() {
        int result = 0;
        Resources resources = activityRootView.getResources();
        int resourceId = resources.getIdentifier("status_bar_height", "dimen", "android");
        if (resourceId > 0) {
            result = resources.getDimensionPixelSize(resourceId);
        }
        return result;
    }

    private int getNavBarHeight() {
        Resources resources = activityRootView.getResources();
        int resourceId = resources.getIdentifier("navigation_bar_height", "dimen", "android");
        if (resourceId > 0) {
            return resources.getDimensionPixelSize(resourceId);
        }
        return 0;
    }

    public boolean isSoftKeyboardOpened() {
        return isSoftKeyboardOpened;
    }

}






The next step:
Your activity must implement 
SoftKeyboardStateWatcher.SoftKeyboardStateListener

Declare in your activity

protected SoftKeyboardStateWatcher mSoftKeyboardStateWatcher;


And run following code in onCreate:


int rootId = getRootId();//here you must supply root View id
View root;
if (rootId == 0 || (root = findViewById(rootId)) == null) return;
mSoftKeyboardStateWatcher = new SoftKeyboardStateWatcher(root);
mSoftKeyboardStateWatcher.addSoftKeyboardStateListener(his);

Now you have these methods:

@Override
public void onSoftKeyboardOpened(int keyboardHeightInPx) {
}

@Override
public void onSoftKeyboardClosed() {
}

Also do not forget to remove listener:


@Override
public void onDestroy() {
    if (mSoftKeyboardStateWatcher != null)
        mSoftKeyboardStateWatcher.removeSoftKeyboardStateListener(this);
    super.onDestroy();
}

It's time to choose new ORM

https://www.raizlabs.com/dev/2015/02/go-dbflow-fastest-android-orm-database-library/