Does AdapterView deserve attention?

[fada21]

I was thinking about adding some AdapterView extentions. Some listeners setting extentions first for those:

• setOnItemClickListener
• setOnItemLongClickListener
• setOnItemSelectedListener

I'm using them for Spinners in my project atm. Should I prepare PR?

[romainguy]

What would the extensions do?

[fada21]

I'll just post method signature here. Later today or tomorrow prepare PR to be more precise and kick off detailed discussion.

@Suppress("UNCHECKED_CAST")
inline fun <ITEM> AdapterView<*>.onItemClick(
    crossinline onItemClick: (item: ITEM) -> Unit
)

@Suppress("UNCHECKED_CAST")
inline fun <ITEM> AdapterView<*>.onItemLongClick(
    crossinline onItemLongClick: (item: ITEM) -> Boolean
)

inline fun AdapterView<*>.onItemSelected(
    crossinline onNothingSelected: () -> Unit = {},
    crossinline onItemSelected: (parent: AdapterView<*>?, view: View?, position: Int, id: Long) -> Unit
)

@Suppress("UNCHECKED_CAST")
inline fun <ITEM> AdapterView<*>.onItemSelected(
    crossinline onNothingSelected: () -> Unit = {},
    crossinline onItemSelected: (item: ITEM) -> Unit
)

Generally some sugar on the AdapterView setting click listeners ceremony.

[sohailehmad]

setOnItemSelectedListener can be shorten as

inline fun <T> AdapterView<*>.doOnItemSelected(crossinline block: (item:T) -> Unit) {
    onItemSelectedListener = object: AdapterView.OnItemSelectedListener {
        override fun onNothingSelected(parent: AdapterView<*>?) {
        }

        @Suppress("UNCHECKED_CAST")
        override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
            block(selectedItem as T)
        }
    }
}

Then we can use this extension like this

adapterView.doOnItemSelected<T> {
    //here Type of it will be T
}

[fada21]

Work in progres PR is ready https://github.com/android/android-ktx/pull/484. I need to finish some tests but most importantly I'm waiting for feedback on implementation.

[fada21]

@sohailehmad please note that with default argument for onNothingSelected you still can use method without specifying both arguments and can invoke it like that:

adapterView.onItemSelected<ITEM> { /* action */ }

I'd agree that onNothingSelected is rarely used but getting rid of of it completely as in your implementation proposition might not be the best options. Especially that we can have concise and general method that handle both arguments.

[fada21]

PR updated and ready for review.