I have created a custom button in a Fragment and I am trying to open the Navigation Drawer in the Activity when it is clicked.
The Navigation Drawer still opens ok when you swipe across, but the app just crashes when I click the button.
I guess this is because I am trying to access from the Fragment, but I am at a loss..
Fragment
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
// Inflate the layout for this fragment
val binding: SiteFragmentBinding = DataBindingUtil.inflate(
inflater, R.layout.site_fragment, container, false
)
binding.apply {
siteOverflowOptionsMenuButton.setOnClickListener{
showPopUp(it)
}
siteDrawerMenuButton.setOnClickListener{
drawer_layout.openDrawer(nav_view) // this crashes (also crashes with Gravity.LEFT or similar)
}
}
return binding.root
}
activity.xml
?xml version="1.0" encoding="utf-8"?>
<androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:fitsSystemWindows="true"
tools:openDrawer="start">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<androidx.fragment.app.FragmentContainerView
android:id="@+id/siteNavHostFragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/site_navigation" />
</LinearLayout>
<com.google.android.material.navigation.NavigationView
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:id="@+id/nav_view"
app:headerLayout="@layout/nav_header"
app:menu="@menu/drawer_menu"
/>
</androidx.drawerlayout.widget.DrawerLayout>
site_fragment.xml
<?xml version="1.0" encoding="utf-8"?> <layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools"> <data> </data> <androidx.constraintlayout.widget.ConstraintLayout android:id="@+id/siteMainConstraintLayout" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/white" tools:context=".site.SiteActivity" > <androidx.constraintlayout.widget.ConstraintLayout android:id="@+id/siteLogoConstraintLayout" android:layout_width="wrap_content" android:layout_height="50dp" android:layout_marginTop="16dp" android:foregroundGravity="center_horizontal" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent"> <ImageView android:id="@+id/siteLogoImage" android:layout_width="50dp" android:layout_height="match_parent" android:src="@mipmap/ic_launcher_logo" app:layout_constraintEnd_toStartOf="@id/siteTopHeadingText" app:layout_constraintHorizontal_chainStyle="packed" app:layout_constraintStart_toStartOf="parent" /> <TextView android:id="@+id/siteTopHeadingText" android:layout_width="wrap_content" android:layout_height="match_parent" android:gravity="center_vertical" android:paddingStart="12dp" android:paddingLeft="12dp" android:text="@string/site_top_heading" android:textAppearance="@style/TextAppearance.AppCompat.Medium" android:textSize="18sp" android:textStyle="bold|italic" app:layout_constraintEnd_toEndOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout> <ImageView android:id="@+id/siteOverflowOptionsMenuButton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="16dp" android:layout_marginRight="16dp" app:srcCompat="@drawable/ic_menu_vertical_dots" android:tint="@color/locatorsPurpleCompany" app:layout_constraintBottom_toBottomOf="@+id/siteLogoConstraintLayout" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="@+id/siteLogoConstraintLayout" /> <ImageView android:id="@+id/siteDrawerMenuButton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="16dp" android:layout_marginLeft="16dp" app:srcCompat="@drawable/ic_menu_drawer" android:tint="@color/locatorsPurpleCompany" app:layout_constraintBottom_toBottomOf="@+id/siteLogoConstraintLayout" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="@+id/siteLogoConstraintLayout" /> <androidx.cardview.widget.CardView android:id="@+id/siteFilterOptionsCardView" android:layout_width="match_parent" android:layout_height="60dp" android:layout_marginStart="8dp" android:layout_marginTop="8dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" app:cardBackgroundColor="@color/locatorsGrey" app:cardCornerRadius="18dp" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/siteLogoConstraintLayout"> <androidx.constraintlayout.widget.ConstraintLayout android:id="@+id/siteFilterOptionsConstraintLayout" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageView android:id="@+id/siteFilterIconImageView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" app:srcCompat="@drawable/ic_filter" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <TextView android:id="@+id/siteCurrentFilterTextView" android:layout_width="0dp" android:layout_height="0dp" android:layout_marginStart="8dp" android:layout_marginLeft="8dp" android:layout_marginTop="4dp" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" android:layout_marginBottom="4dp" android:background="@color/white" android:drawableLeft="@drawable/ic_search" android:drawablePadding="8dp" android:ellipsize="end" android:gravity="center_vertical" android:lines="1" android:paddingLeft="12dp" android:paddingRight="12dp" android:text="Search..." app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toStartOf="@+id/siteClearIconImageView" app:layout_constraintStart_toEndOf="@+id/siteFilterIconImageView" app:layout_constraintTop_toTopOf="parent" /> <ImageView android:id="@+id/siteClearIconImageView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="8dp" android:layout_marginRight="8dp" app:srcCompat="@drawable/ic_clear" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout> </androidx.cardview.widget.CardView> <androidx.recyclerview.widget.RecyclerView android:id="@+id/siteRecyclerView" android:layout_width="match_parent" android:layout_height="0dp" android:layout_marginBottom="4dp" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toBottomOf="@+id/siteFilterOptionsCardView" app:layout_constraintVertical_bias="0.0" tools:listitem="@layout/site_list_item" /> <com.google.android.material.floatingactionbutton.FloatingActionButton android:id="@+id/floatingActionButtonAdd" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginEnd="32dp" android:layout_marginRight="32dp" android:layout_marginBottom="24dp" android:backgroundTint="@color/locatorsPurpleCompany" android:clickable="true" android:elevation="28dp" app:borderWidth="0dp" app:fabSize="normal" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="@+id/siteRecyclerView" app:srcCompat="@drawable/ic_add_white" /> </androidx.constraintlayout.widget.ConstraintLayout> </layout>
drawer_menu.xml
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
>
<group android:checkableBehavior="single">
<item
android:id="@+id/nav_first_fragment"
android:icon="@drawable/ic_exit"
android:title="First" />
<item
android:id="@+id/nav_second_fragment"
android:icon="@drawable/ic_priority"
android:title="Second" />
<item
android:id="@+id/nav_third_fragment"
android:icon="@drawable/ic_filter"
android:title="Third" />
</group>
<item android:title="Communicate">
<menu>
<item
android:id="@+id/nav_share"
android:icon="@drawable/ic_contact"
android:title="Share" />
<item
android:id="@+id/nav_send"
android:icon="@drawable/ic_location"
android:title="Send" />
</menu>
</item>
<item android:title="Sub items">
<menu>
<group android:checkableBehavior="single">
<item
android:icon="@drawable/ic_star_full"
android:title="Sub item 1" />
<item
android:icon="@drawable/ic_location"
android:title="Sub item 2" />
</group>
</menu>
</item>
</menu>
Crash Log
2020-02-17 12:31:56.719 23527-23527/com.locators.acorn E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.locators.acorn, PID: 23527
java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.drawerlayout.widget.DrawerLayout.openDrawer(int)' on a null object reference
at com.locators.acorn.site.SiteFragment$onCreateView$$inlined$apply$lambda$2.onClick(SiteFragment.kt:46)
at android.view.View.performClick(View.java:7125)
at android.view.View.performClickInternal(View.java:7102)
at android.view.View.access$3500(View.java:801)
at android.view.View$PerformClick.run(View.java:27336)
at android.os.Handler.handleCallback(Handler.java:883)
at android.os.Handler.dispatchMessage(Handler.java:100)
at android.os.Looper.loop(Looper.java:214)
at android.app.ActivityThread.main(ActivityThread.java:7356)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
In your implementation, you don't do that as drawer_layout
is not accessible from fragment
. Hence you got NullPointerException
. Try to follow below steps:
Step - 1: Create a function in your Activity
to open-close Navigation Drawer
fun openCloseNavigationDrawer(view: View) {
if (drawer_layout.isDrawerOpen(GravityCompat.START)) {
drawer_layout.closeDrawer(GravityCompat.START)
} else {
drawer_layout.openDrawer(GravityCompat.START)
}
}
Step - 2: Invoke openCloseNavigationDrawer
from your fragment
OnClickListener
from your fragment code and add onClick
property through layout and pointed out the function openCloseNavigationDrawer
on siteDrawerMenuButton
. <ImageView
android:id="@+id/siteDrawerMenuButton"
android:onClick="openCloseNavigationDrawer"
... />
openCloseNavigationDrawer
through code by casting your Activity
like below: siteDrawerMenuButton.setOnClickListener{ v ->
(activity as YOUR_ACTIVITY).openCloseNavigationDrawer(v)
}
A bit late to the party, but in case someone finds this useful - it's a single line with Jetpack Binding:
class LoginViewModel ( applicationParam: Application ) : AndroidViewModel ( applicationParam )
{
screenViews = FragmentLoginBinding.inflate ( inflater,container,false )
override fun onViewCreated ( view: View, savedInstanceState: Bundle? )
{
// Set click listener for the Log in button
screenViews.login.setOnClickListener { submitLogin() }
// Set the click listener for the element that selects the register fragment from the navigation drawer
screenViews.goToRegisterFragment.setOnClickListener { findNavController().navigate ( R.id.nav_register ) }
}
}
With LoginViewModel being the view model for a fragment called Login, and R_id_nav_register being an element in mobile_navigation.xml and activity_main_drawer.xml
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