How can I remove my NullPointerException?

Question

I retry to post my question because I don't have receive an answer : my app close itself when i click, an I find as cause that :

    Process: fr.amseu.mystretching, PID: 15005
    java.lang.RuntimeException: Unable to start activity ComponentInfo{fr.amseu.mystretching/fr.amseu.mystretching.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3556)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:237)
        at android.app.ActivityThread.main(ActivityThread.java:7948)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ImageButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at fr.amseu.mystretching.MainActivity.onCreate(MainActivity.kt:17)
        at android.app.Activity.performCreate(Activity.java:7955)
        at android.app.Activity.performCreate(Activity.java:7944)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1307)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3531)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3703) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2216) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:237) 
        at android.app.ActivityThread.main(ActivityThread.java:7948) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1075)

As context, I give my Main activity :


    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val exerciseButton = findViewById<ImageButton>(R.id.imageButton)

        exerciseButton.setOnClickListener {
            val intent = Intent(this, SecondActivity::class.java)
            startActivity(intent)
        }

My layout which contain the Image button. It is a part of a recycler view if it change anything ? :

<ImageButton
            android:id="@+id/imageButton"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            android:src="@drawable/lower_legs"
            android:contentDescription="@string/home_page_first_button" />

And I have finally my second activity (as a kotlin class file), where the click should redirect me :

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_exercices)
    }
}

Thanks for any help...

Please don’t repost questions. Update the existing one with additional detail. — Tenfour04, Apr 24 '21 at 19:20

score 0 · Answer 1 · answered Apr 24 '21 at 19:22

My layout which contain the Image button. It is a part of a recycler view if it change anything ?

It does change a lot. You're trying to find a view that does not exist when onCreate is called because you have not initialized the recycler view or its adapter (as far as the code you showed).

See this post for handling a click on a RecyclerView item: RecyclerView onClick

How can I remove my NullPointerException?

1 Answers1