3.4 Searching in a List View

If we wanted to search for an item within a ListView, we would have to somehow get input from the user which is something we can do with a specific view type.

The EditText will allow us to get user input we can then filter our list with.

EditText example

Once we have an EditText we can create an addTextChangedListenerto it to customize the behavior on such actions:

editText.addTextChangedListener(object : TextWatcher {
      override fun afterTextChanged(s: Editable?) {
      }
      override fun beforeTextChanged(s: CharSequence?, start: Int, count: Int, after: Int) {
      }
      override fun onTextChanged(s: CharSequence?, start: Int, before: Int, count: Int) {
      // requery/filter your adapter then set it to your listview
      }
    })

The above code has 3 overridden functions:

• afterTextChanged

  • This method is called to notify you that, somewhere within s, the text has been changed.

• beforeTextChanged

  • This method is called to notify you that, within s, the count characters beginning at start are about to be replaced by new text with length after.

• onTextChanged

  • This method is called to notify you that, within s, the count characters beginning at start have just replaced old text that had length before.

onTextChangedis the method in which we will requery our adapter and then set it to our list view to change the results of what is displayed after searching; effectively searching.