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Android Studio – java.lang.NullPointerException null object reference viewpager

I am stuck while coding and need help on that.
I am using view binding in my project.
I have unable binding and that is working fine.
I have used same code in my earlier project except view binding and that project was working fine.

Here is my XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="5dp"
tools:context=".Home">

<androidx.viewpager.widget.ViewPager
    android:id="@+id/pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_above="@id/bottom_navigation" />

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/bottom_navigation"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    app:menu="@menu/bottom_navigation_menu" />

</RelativeLayout>

Here is my Java code

package com.example.professionals;

public class Home extends AppCompatActivity {

private ActivityHomeBinding Homebinding;
protected ViewPager viewPager;
protected Mypager_Adapter mypager_adapter;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    Homebinding = ActivityHomeBinding.inflate(getLayoutInflater());
    View view = Homebinding.getRoot();
    setContentView(view);

    Homebinding.pager.findViewById(R.id.pager);
    mypager_adapter = new Mypager_Adapter(this);
    viewPager.setAdapter(mypager_adapter);

    Homebinding.bottomNavigation.setOnItemSelectedListener(new 
    NavigationBarView.OnItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()) {
                case R.id.home:
                    showMsg("Home");
                    break;
                case R.id.profile:
                    showMsg("Profile");
                    break;
            }
            return false;
        }
    });
}

private void showMsg(String msg) {
    Toast toast = Toast.makeText(this, msg, Toast.LENGTH_LONG);
    toast.show();
}
}

Here is the error list

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.professionals, PID: 17743
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.professionals/com.example.professionals.Home}: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.viewpager.widget.ViewPager.setAdapter(androidx.viewpager.widget.PagerAdapter)' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2473)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2535)
    at android.app.ActivityThread.access$1100(ActivityThread.java:154)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1396)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:148)
    at android.app.ActivityThread.main(ActivityThread.java:5582)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void androidx.viewpager.widget.ViewPager.setAdapter(androidx.viewpager.widget.PagerAdapter)' on a null object reference
    at com.example.professionals.Home.onCreate(Home.java:32)
    at android.app.Activity.performCreate(Activity.java:6321)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1108)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2426)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2535) 
    at android.app.ActivityThread.access$1100(ActivityThread.java:154) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1396) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5582) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

Thanks in advance for help!

Tags:

2

Answers


  1. 0

    You need to add

    viewPager = findViewById<ViewPager>(R.id.pager)

    Before this line

    viewPager.setAdapter(mypager_adapter);

    Edit:

    Actually it seems like you’re attempting to use ViewBinding as well as regular findViewById, if I were you I’d stick with ViewBinding and delete this line

    protected ViewPager viewPager;

    Then try this instead

    Homebinding.pager.setAdapter(mypager_adapter);
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  2. 0

    You haven’t initialize your ViewPager.

    You need initialize your viewPager. For that you have couple of options

    Initialize with findViewById before setting adapter.

    viewPager = findViewById(R.id.pager)

    As you are using view binding would be the good idea

    Homebinding.pager.setAdapter(mypager_adapter)
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