Drag and drop in Android. All you need to know
Have you ever been in a situation where you needed to create an Android app with drag and drop feature? I was. And if you were too, I know what you might feel right now, believe me. At the beginning it will look like something very complicated with calculations of touches, drags, movement of the objects and many things like that 🤪, but in reality, there is a very nice API in the Android Framework, so we just need to use it 😌. Let’s see how it works in reality.
Let’s create a simple app, where we will have random words, and from those words we will create a sentence. Each word will be represented as a box, and by dragging and dropping we will form our sentence. So, from the UI point of view, there should be two Recycler Views. One for mixed words, second for a sentence (ordered words).
Basically, this is how our app will look like.
Huh, nice one!
Let’s bring some magic here!
We have two components. The first one is from where the items will be dragged, and the second — where will be dropped.
Let’s start from the first one. In the demo project, drag will start on a long click on each recycler view item. So, in the adapter’s view holder, let’s add a LongClickListener to each item.
Here, the instance of ClipData is a simple data about the draggable item, and the DragShadowBuilder is the image, represented to a user during the drag process.
Now we can drag words, but we can’t drop them.
To be able to drop, let’s implement a DragListener…
… and apply it to sentence recycler view.
What’s next?
Nothing!
Yeah, this is all you need. The basic stuff to implement a simple drag and drop in any Android application. You can add more tweaks to make the drag and drop process more suitable for your application.
I’ve created a demo project, which may be useful, if this guide is not enough for you or you’re just lazy, and the only thing you want to read is a code.
Happy coding!
Also you can follow or contact me:
Twitter: https://twitter.com/RobertLevonyan
Github: https://github.com/robertlevonyan
Email: me@robertlevonyan.com
Website: https://robertlevonyan.com
