findViewById(R.id.icon) returns null

Question

R.id.icon is already defined in Android API level 1. However, I am getting an NPE in a Android Design Support Library internal code while accessing an imageview inflated using R.id.icon.

NOTE: I am not targetting Oreo as my targetSdk is currently 25 .

Here is the stacktrace:

   Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference
   at android.support.design.internal.BottomNavigationItemView.setChecked(BottomNavigationItemView.java:172)
   at android.support.design.internal.BottomNavigationItemView.initialize(BottomNavigationItemView.java:97)
   at android.support.design.internal.BottomNavigationMenuView.buildMenuView(BottomNavigationMenuView.java:276)
   at android.support.design.internal.BottomNavigationPresenter.updateMenuView(BottomNavigationPresenter.java:62)
   at android.support.design.widget.BottomNavigationView.inflateMenu(BottomNavigationView.java:238)
   at android.support.design.widget.BottomNavigationView.<init>(BottomNavigationView.java:167)
   at android.support.design.widget.BottomNavigationView.<init>(BottomNavigationView.java:116)
   at java.lang.reflect.Constructor.newInstance(Native Method) 
   at java.lang.reflect.Constructor.newInstance(Constructor.java:288) 
   at android.view.LayoutInflater.createView(LayoutInflater.java:607) 
   at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:743) 
   at android.view.LayoutInflater.rInflate(LayoutInflater.java:806) 
   at android.view.LayoutInflater.inflate(LayoutInflater.java:504) 
   at android.view.LayoutInflater.inflate(LayoutInflater.java:414) 
   at android.view.LayoutInflater.inflate(LayoutInflater.java:365) 
   at android.support.v7.app.AppCompatDelegateImplV9.setContentView(AppCompatDelegateImplV9.java:292) 
   at android.support.v7.app.AppCompatActivity.setContentView(AppCompatActivity.java:140) 
  at com.who.android.app.layout.activities.Sample_Mock.onCreate(Sample_Mock.java:40) 
  at android.app.Activity.performCreate(Activity.java:6033) 
  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106) 
  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278) 
  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) 
  at android.app.ActivityThread.access$800(ActivityThread.java:151) 
  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
  at android.os.Handler.dispatchMessage(Handler.java:102) 
  at android.os.Looper.loop(Looper.java:135) 
  at android.app.ActivityThread.main(ActivityThread.java:5254) 
  at java.lang.reflect.Method.invoke(Native Method) 
  at java.lang.reflect.Method.invoke(Method.java:372) 
  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)

On investigation, I found out that the code in BottomNavigationItemView.java is trying to access a null ImageView inflated with R.id.icon resource.

            LayoutParams iconParams = (LayoutParams) mIcon.getLayoutParams();

where mIcon is null and has been inflated as

    mIcon = (ImageView) findViewById(R.id.icon);

Edit: I created a new BottomNavigationActivity from Android's Gallery and redirected the navigation to this mock class instead of mine. Still I am facing the same issue. Here are the pristine java code and the layout xml code for the new mocked activity :

package com.who.android.app.layout.activities;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.support.v7.app.AppCompatActivity;
import android.view.MenuItem;
import android.widget.TextView;

import com.who.android.app.R;

public class Sample_Mock extends AppCompatActivity {

  private TextView mTextMessage;

  private BottomNavigationView.OnNavigationItemSelectedListener mOnNavigationItemSelectedListener
        = new BottomNavigationView.OnNavigationItemSelectedListener() {

    @Override
    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
        switch (item.getItemId()) {
            case R.id.navigation_home:
                mTextMessage.setText(R.string.title_home);
                return true;
            case R.id.navigation_dashboard:
                mTextMessage.setText(R.string.title_dashboard);
                return true;
            case R.id.navigation_notifications:
                mTextMessage.setText(R.string.title_notifications);
                return true;
        }
        return false;
    }

  };

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_sample__mock);

    mTextMessage = (TextView) findViewById(R.id.message);
    BottomNavigationView navigation = (BottomNavigationView) findViewById(R.id.navigation);
    navigation.setOnNavigationItemSelectedListener(mOnNavigationItemSelectedListener);
  }

}

Here is the pristine layout file where I use the BottomNavigationView (as created by Android, I have not touched it)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com._._._._.activities.Sample_Mock">

    <FrameLayout
        android:id="@+id/content"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1">

        <TextView
            android:id="@+id/message"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginBottom="@dimen/activity_vertical_margin"
            android:layout_marginLeft="@dimen/activity_horizontal_margin"
            android:layout_marginRight="@dimen/activity_horizontal_margin"
            android:layout_marginTop="@dimen/activity_vertical_margin"
            android:text="@string/title_home"/>

    </FrameLayout>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:background="?android:attr/windowBackground"
        app:menu="@menu/navigation"/>

</LinearLayout> 

The version of Android Design Support Library and Android AppCompat support libraries I am using are both 25.3.1

com.android.support:design:25.3.1
com.android.support:appcompat-v7:25.3.1

Can anyone help me in understanding why I am getting a null reference out of inflating from R.id.icon ? This code is beyond my control as it is internal to the Android Design Support library. Also, as I showed that this problem occurs in a newly created BottomNavigationActivity as well, is there a problem with the library version I am using? Because this version has been working fine for last several months for me.

Edit 2: I created another project altogether with just one BottomNavigationActivity in it. Guess what? Same error there. So it seems to me do be an Android Design Support Library issue.

Edit 3: menu/navigation.xml As you can see, it is standard.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">

    <item
        android:id="@+id/navigation_home"
        android:icon="@drawable/ic_home_black_24dp"
        android:title="@string/title_home"/>

    <item
        android:id="@+id/navigation_dashboard"
        android:icon="@drawable/ic_dashboard_black_24dp"
        android:title="@string/title_dashboard"/>

    <item
        android:id="@+id/navigation_notifications"
        android:icon="@drawable/ic_notifications_black_24dp"
        android:title="@string/title_notifications"/>

</menu>

Answer 1

I had similar issue after increasing target API level to 31.

Due to requirement for pending intents mutability, I had to update Navigation dependency to 2.4.0-alpha04 or higher, so that pending intents created via NavDeepLinkBuilder.createPendingIntent() specify mutability. However, the application started crashing with an exception similar to yours.

The solution was to replace R.id.icon with R.id.navigation_bar_item_icon_view.