As kotlin has taken over most of Android development ecosystem, by now we all are aware of all the goodies that kotlin offers. One of the most liked goodies is extension-functions.
Following are some of the extension-functions that come in handy in day-to-day android application development.
Showing/ hiding views
fun View.visibleOrGone(show: Boolean = false) {
this.visibility = if(show) {
View.VISIBLE
} else {
View.GONE
}
Hide Keyboard
fun View.hideKeyboard() {
(context.getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager)?.let { inputManager ->
inputManager.hideSoftInputFromWindow(windowToken, 0)
}
}
EditText after text changed
We can pass the function to be performed after edit text input changes as closure.
fun EditText.afterTextChanged(afterTextChanged: (String) -> Unit) {
this.addTextChangedListener(object : TextWatcher {
override fun afterTextChanged(s: Editable?) {
afterTextChanged.invoke(s?.toString())
}
override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) { // na
}
override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) { // na
}
})
}
RecyclerView set divider
dividerResId is the divider drawable if we have to provide custom divider.
fun RecyclerView.setDivider(dividerResId: Int? = null, orientation: Int = DividerItemDecoration.VERTICAL) {
val dividerItemDecoration = DividerItemDecoration(this.context, orientation)
dividerResId?.let { resId ->
this.context.getDrawableResource(resId)
?.let { divider ->
dividerItemDecoration.setDrawable(divider)
}
}
this.addItemDecoration(dividerItemDecoration)
}
Accessing resources with ContextCompact
fun Context.getColorResource(colorRes: Int): Int {
return ContextCompat.getColor(this, colorRes)
}
fun Context.getDrawableResource(drawableRes: Int): Drawable? {
return ContextCompat.getDrawable(this, drawableRes)
}
TextView extensions to set drawable
fun TextView.setDrawable(
@DrawableRes
drawable: Int, start: Boolean, end: Boolean, top: Boolean, bottom: Boolean
) {
when {
start -> this.setCompoundDrawablesRelativeWithIntrinsicBounds(drawable, 0, 0, 0)
end -> this.setCompoundDrawablesRelativeWithIntrinsicBounds(0, 0, drawable, 0)
top -> this.setCompoundDrawablesRelativeWithIntrinsicBounds(0, drawable, 0, 0)
bottom -> this.setCompoundDrawablesRelativeWithIntrinsicBounds(0, 0, 0, drawable)
}
this.compoundDrawablePadding = 8
}
I hope this will be helpful. I will add more in future. Please provide feedback in comments.
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