My app worked just fine, i could go from one activity to another then i add some Toast messages for Registration button then i got this error when i'm trying to go from **MainActivity** to **RegistrationActivity**..

*MainActivity.kt*

```
import android.widget.Toast
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import kotlinx.android.synthetic.main.activity_main.*
import java.io.File
import java.io.FileReader
import java.io.InputStream
import java.util.jar.Manifest

class MainActivity : AppCompatActivity() {

    // private val STORAGE_PERMISSION_CODE = 1

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

        btnLogin.setOnClickListener {
            Toast.makeText(this,"Some message", Toast.LENGTH_SHORT).show()
        }

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

```

*RegistrationActivity.kt*

```
package com.example.myapplication

import android.content.Intent
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import kotlinx.android.synthetic.main.activity_registration.*

class RegistrationActivity : AppCompatActivity(){

    val userName = etUserName.text.toString()
    val userEmail = etUserEmail.text.toString()
    val userPassword = etPassword.text.toString()
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_registration)

        btnRegistration.setOnClickListener {
            if(validate() == false)
                 Toast.makeText(this,"Incomplete data", Toast.LENGTH_SHORT).show()
             else
             {
                 Toast.makeText(this, "Registration successed", Toast.LENGTH_SHORT).show()
                 // update database
             }
        }
    }

```

*activity\_main.xml*

```
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/btnLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Login"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.569" />

    <TextView
        android:id="@+id/tvGoToRegistration"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Go to registration"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btnLogin" />
</androidx.constraintlayout.widget.ConstraintLayout>

```

*activity\_registraion.xml*

```
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    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:orientation="vertical">

    <EditText
        android:id="@+id/etUserName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="name.."
        android:inputType="textPersonName"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.155" />

    <EditText
        android:id="@+id/etUserEmail"
        style="@android:style/Widget.DeviceDefault.Light.EditText"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="email.."
        android:inputType="textEmailAddress"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etUserName"
        app:layout_constraintVertical_bias="0.147" />

    <EditText
        android:id="@+id/etPassword"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:ems="10"
        android:hint="password.."
        android:inputType="textPassword"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etUserEmail"
        app:layout_constraintVertical_bias="0.165" />

    <TextView
        android:id="@+id/tvBackToLogin"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Already sign in? Login"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.497"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btnRegistration" />

    <Button
        android:id="@+id/btnRegistration"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Register"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/etPassword"
        app:layout_constraintVertical_bias="0.383" />
</androidx.constraintlayout.widget.ConstraintLayout>

```

*manifest*

```
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myapplication">
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <activity android:name=".RegistrationActivity"/>
        <activity android:name=".Test"/>
    </application>

</manifest> 

```

*And logchat*

> 
> 2019-12-09 09:08:16.171 28691-28691/com.example.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
>  Process: com.example.myapplication, PID: 28691
>  java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.myapplication/com.example.myapplication.RegistrationActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
>  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2548)
>  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
>  at android.app.ActivityThread.-wrap12(ActivityThread.java)
>  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
>  at android.os.Handler.dispatchMessage(Handler.java:102)
>  at android.os.Looper.loop(Looper.java:154)
>  at android.app.ActivityThread.main(ActivityThread.java:6077)
>  at java.lang.reflect.Method.invoke(Native Method)
>  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
>  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
>  Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.pm.ApplicationInfo android.content.Context.getApplicationInfo()' on a null object reference
>  at android.content.ContextWrapper.getApplicationInfo(ContextWrapper.java:149)
>  at android.view.ContextThemeWrapper.getTheme(ContextThemeWrapper.java:157)
>  at android.content.Context.obtainStyledAttributes(Context.java:575)
>  at androidx.appcompat.app.AppCompatDelegateImpl.createSubDecor(AppCompatDelegateImpl.java:692)
>  at androidx.appcompat.app.AppCompatDelegateImpl.ensureSubDecor(AppCompatDelegateImpl.java:659)
>  at androidx.appcompat.app.AppCompatDelegateImpl.findViewById(AppCompatDelegateImpl.java:479)
>  at androidx.appcompat.app.AppCompatActivity.findViewById(AppCompatActivity.java:214)
>  at com.example.myapplication.RegistrationActivity.\_$\_findCachedViewById(RegistrationActivity.kt)
>  at com.example.myapplication.RegistrationActivity.(RegistrationActivity.kt:10)
>  at java.lang.Class.newInstance(Native Method)
>  at android.app.Instrumentation.newActivity(Instrumentation.java:1079)
>  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2538)
>  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
>  at android.app.ActivityThread.-wrap12(ActivityThread.java) 
>  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
>  at android.os.Handler.dispatchMessage(Handler.java:102) 
>  at android.os.Looper.loop(Looper.java:154) 
>  at android.app.ActivityThread.main(ActivityThread.java:6077) 
>  at java.lang.reflect.Method.invoke(Native Method) 
>  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
>  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 
> 
> 
> 

I think the error is caused by startActivity(intent) in MainActivity but when i run it in debbuger i can go past that line but i can't enter the RegistrationActivity class