I tried to this code which is mention below, but getting crash during run time. The error occurred is Android Run time:
FATAL EXCEPTION: main Process: com.root.specialbridge, PID: 17706 kotlin.KotlinNullPointerException at com.root.specialbridge.fragments.profile_fragment.WallFragments.initializeView(WallFragments.kt:49)
class WallFragments : Fragment(){
private var wallAdapter: WallAdapter? = null
private var wall_recycler: RecyclerView? = null
private val wallArrayList: ArrayList<Wall>? = null
private var mainlayout: LinearLayout? = null
private var no_result_found_layout: RelativeLayout? = null
private var userProfileWallInterface: UserProfileWallInterface? = null
internal var wallActivityBeanse: MutableList<WallActivityBeans> = ArrayList()
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?, savedInstanceState: Bundle?): View? {
val view = inflater!!.inflate(R.layout.wall_fragments, container, false)
userProfileWallInterface = UserProfileWallPresentation(activity, this)
initializeView()
wallAdapter = WallAdapter(activity, wallActivityBeanse)
wall_recycler!!.adapter = wallAdapter
return view
}
fun initializeView() {
wall_recycler = view!!.findViewById(R.id.wall_recycler_id) as RecyclerView
mainlayout = view!!.findViewById(R.id.mainlayout) as LinearLayout
no_result_found_layout = view!!.findViewById(R.id.no_result_found_layout) as RelativeLayout
wall_recycler!!.layoutManager = LinearLayoutManager(activity)
wall_recycler!!.setHasFixedSize(true)
if (AuthPreference(activity).isGetMemberProfile) {
userProfileWallInterface!!.getMemberProfileWall(view!!)
} else {
userProfileWallInterface!!.getUserProfileWall(AuthPreference(activity).token, AuthPreference(activity).user.id, view!!)
}
}
companion object {
val instance: WallFragments
get() = WallFragments() }}
Add
apply plugin: 'kotlin-android-extensions'
in the app level gradle file and
import
import kotlinx.android.synthetic.main.fragment_your_fragment_name.view.*
in the onCreateView
of your fragment (e.g. if the id of your textview is textView)
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
val view = inflater!!.inflate(R.layout.fragment_splashfragment, container, false)
view.textView.text = "hello" //add your view before id else getting nullpointer exception
return view
}
UPDATE:
declare viewOfLayout in your class instead of view.
class yourfragment:Fragment(){
private lateinit var viewOfLayout: View
override fun onCreateView(inflater: LayoutInflater?, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
viewOfLayout = inflater!!.inflate(R.layout.fragment_splashfragment, container, false)
viewOfLayout.textView.text = "hello" //add your view before id else will get nullpointer exception
return viewOfLayout
}
}
Introducing Kotlin Android Extensions.
You do not have to use findViewById
anymore. Using this plugin you can use the UI component directly as a global field. Supported in Activities
, fragments
and views
.
Example, To refer text view from the layout below,
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="@+id/hello"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Hello World, MyActivity"/>
</android.support.constraint.ConstraintLayout>
in activity you can simply write,
// Using R.layout.activity_main from the main source set
import kotlinx.android.synthetic.main.activity_main.*
class MyActivity : Activity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Instead of findViewById(R.id.hello) as TextView
hello?.setText("Hello, world!")
}
}
in fragments,
// Using R.layout.fragment_content from the main source set
import kotlinx.android.synthetic.main.fragment_content.*
class ContentFragment : Fragment() {
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
inflater.inflate(R.layout.fragment_content, container, false)
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
// Instead of view.findViewById(R.id.hello) as TextView
hello?.setText("Hello, world!")
}
}
and for views,
// Using R.layout.item_view_layout from the main source set
import kotlinx.android.synthetic.main.item_view_layout.*
class ItemViewHolder(view: View) : RecyclerView.ViewHolder(view) {
fun bindData(data: String) {
// Instead of itemView.findViewById(R.id.hello) as TextView
itemView.hello?.setText(data)
}
}
And, you should not use !!
everywhere, unless you want NullPointerException
explicitly.
Instead use anyone from the following:
?.
, Eg. nullableVariable?.method()
?.let{ }
, Eg. nullableVariable?.let { it.method() }
?:
, Eg. nullableVariable ?: <backupValue>
.Read more about Null Safety in Kotlin.
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