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Android: Detect a fling

If you want to detect a fling on a view, create a GestureDetector that for an argument takes a SimpleOnGestureListener.

final static GestureDetector.SimpleOnGestureListener simpleDetector = new GestureDetector.SimpleOnGestureListener() {
    public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
        super.onFling(e1, e2, velocityX, velocityY);
        Log.d("HI", "on fling");
        return true; // If you've consumed it
final static GestureDetector detector = new GestureDetector(simpleDetector);

It’s within these methods you calculate what kind of fling it is.

Within your onTouch event listener return with return detector.onTouchEvent(motionEvent);.

And make sure the view you’re listening on is clickable. And that should be it.

android android-fling

Android: Simple view dragging tutorial

Let’s say you’ve added a touch listener to a view. And in that listener you have a motionEvent.

Use this code to start dragging that view in onTouch.

if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
    ClipData data = ClipData.newPlainText("", "");
    View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(
    view.startDrag(data, shadowBuilder, view, 0);
    return true;
} else {
    return false;

The clipdata is the data passed to the drop area. And the shadowBuilder is what the view looks like when dragged.

There’s no drop area, but you can look that up.

android android-drag-drop

Android and Facebook's Litho: Getting started

Litho allows you to declare your view in code with speed optimisations for lists.

It uses flexbox layout logic, via the Facebook Yoga library, allowing you to use your existing web knowledge. This applies to iOS too since Yoga also exists for iOS.

It supports one-directional data binding, thereby allowing you dive into the flux architecture a little.

Let’s do the basic getting started first. Let’s bung all the depenedencies into your app’s build.gradle.

compile 'com.facebook.litho:litho-core:0.2.0'
compile 'com.facebook.litho:litho-widget:0.2.0'
provided 'com.facebook.litho:litho-annotations:0.2.0'
annotationProcessor 'com.facebook.litho:litho-processor:0.2.0'
compile 'com.facebook.soloader:soloader:0.2.0'
debugCompile 'com.facebook.litho:litho-stetho:0.2.0'
compile 'com.facebook.litho:litho-fresco:0.2.0'

Create an Application class in your app and ensure your manifest points to it. In the onCreate method add this:

SoLoader.init(this, false);

In your Activity’s onCreate change the view layout code to:

 ComponentContext c = new ComponentContext(this);
 setContentView(LithoView.create(c, MyComponent.create(c).build()));

We’re creating a Litho context, and then creating a Litho view with that context, and a component too. Where does that MyComponent come from?

public class MyComponentSpec {
    static ComponentLayout onCreateLayout(ComponentContext c) {
        return Column.create(c)
                .paddingDip(YogaEdge.ALL, 16)


The annoation @LayoutSpec takes the class name minus Spec, thereby creating the MyComponent class via facebook’s annoation processor.

We create a Column using flexbox terminology, with two Text children, which are not TextViews incidentally.

Later tutorials will focus on using Android Views within Litho and events I should think.

android litho

Postgresql: Remove punctuation from field with a regex

Sometimes it’s useful to remove all punctuation from a field.

Take the sentence It's done - and dusted, finally. & that's that.. We’ll use regexp_replace on this.

select regexp_replace(lower($$It's done - and dusted, finally. & that's that. $$),$$\sand\s|[&\.,\s'-]$$,$$$$,$$g$$)

That results in itsdonedustedfinallythatsthat. We’ve also removed the word and.

If we use It's done--and dusted, finally. & that's that. then the \sand\s matcher would fail. It’s an exercise to the reader to work a way around that.

We’ve also not dealt with $ and the like, but that’s also facile to remove using the above.


Using AWK with CSV files with commas inbetween quotation marks

Sometimes you’ll get a CSV like: Here is something, And another thing, "OH LOOK, A COMMA WITHIN QUOTATION MARKS", something else.

This is annoying, since a normal awk separator like -F , will not work. But in modern version of awk, you can use -FPAT to use a regular expression.

Use awk -vFPAT='[^,]*|"[^"]*"'. This says you’re either looking for a field that ends in a comma, or looking for anything that begins and ends with quotation marks.

awk csv

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