ActivityNotFoundException {com.example.greetingcard/androidx.fragment.app.FragmentActivity};

Issue

class FragmentActivity : AppCompatActivity() {

    lateinit var binding : ActivityFragmentBinding

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        binding= ActivityFragmentBinding.inflate(layoutInflater)
        setContentView(binding.root)

        binding.fragment1Button.setOnClickListener {
            replaceFragment(BlankFragment2())
        }

        binding.fragment2Button.setOnClickListener {
            replaceFragment(BlankFragment2())
        }
    }

    private fun replaceFragment(fragment: Fragment) {
        val fragmentManager = supportFragmentManager
        val fragmentTransaction = fragmentManager.beginTransaction()
        fragmentTransaction.replace(R.id.fragment_container_view,fragment)
        fragmentTransaction.commit()
    }
}

This is the Fragment activity.

<activity android:name=".fragments.FragmentActivity">
        </activity>

Declaration in the manifest file.

        fragmentActivityButton.setOnClickListener {
            var intent = Intent(this@MainActivity, FragmentActivity::class.java)
            startActivity(intent)
        }

This is in the MainActivity.(startActivity(intent) is throwing the exception.)

<?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:background="@drawable/button_shape"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/goToSecondButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/button_shape"
        android:backgroundTint="@null"
        android:text="Go to second Activity"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/childLinearLayout" />

    <Button
        android:id="@+id/recyclerViewButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/button_shape"
        android:backgroundTint="@null"
        android:text="go to recycler activity"
        app:layout_constraintBottom_toTopOf="@+id/fragmentButton"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.5" />

    <Button
        android:id="@+id/fragmentButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/button_shape"
        android:backgroundTint="@null"
        android:text="go to fragment activity"
        app:layout_constraintBottom_toTopOf="@+id/text"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/recyclerViewButton"
        app:layout_constraintVertical_bias="0.5" />

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:paddingLeft="5dp"
        android:paddingRight="5dp"
        android:text="Have a good day!"
        android:textAppearance="@style/TextAppearance.AppCompat.Display1"
        android:textColor="@color/white"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <LinearLayout
        android:id="@+id/childLinearLayout"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="5dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/text">

        <Button
            android:id="@+id/resetButton"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:baselineAligned="false"
            android:text="reset"
            app:layout_constraintStart_toStartOf="parent" />

        <Button
            android:id="@+id/changeButton"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp"
            android:layout_weight="1"
            android:baselineAligned="false"
            android:text="change"
            app:layout_constraintEnd_toEndOf="parent" />

    </LinearLayout>


</androidx.constraintlayout.widget.ConstraintLayout>

This is mainactivity xml.

plugins {
    id 'com.android.application'
    id 'org.jetbrains.kotlin.android'
}

android {
    namespace 'com.example.greetingcard'
    compileSdk 33

    defaultConfig {
        applicationId "com.example.greetingcard"
        minSdk 24
        targetSdk 33
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

    buildFeatures{
        viewBinding true
    }

    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.appcompat:appcompat:1.6.1'
    implementation 'com.google.android.material:material:1.9.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.4'
    testImplementation 'junit:junit:4.13.2'
    androidTestImplementation 'androidx.test.ext:junit:1.1.5'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.5.1'
}

This is build.gradle file.

<?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"
    tools:context=".fragments.FragmentActivity">

    <androidx.fragment.app.FragmentContainerView
        android:layout_width="match_parent"
        android:layout_height="600dp"
        android:id="@+id/fragment_container_view"
        android:name="com.example.greetingcard.fragments.BlankFragment" />

    <Button
        android:layout_width="150dp"
        android:layout_height="60dp"
        android:id="@+id/fragment1_button"
        android:backgroundTint="@color/black"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="50dp"
        android:layout_marginStart="30dp"
        android:text="Fragment 1"/>

    <Button
        android:layout_width="150dp"
        android:layout_height="60dp"
        android:id="@+id/fragment2_button"
        android:backgroundTint="@color/black"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="50dp"
        android:layout_marginEnd="30dp"
        android:text="Fragment 1"/>


</RelativeLayout>

This is FragmentActivity xml.

Couldn't find the problem behind the exception. Thanks in advance.

App is crashing giving activity not found exception.

Solution

After many attempts i found the problem.

In your MainActivity you imported the uncorrect FragmentActivity, you named your second activity "FragmentActivity" but FragmentActivity is an Android default Activity of androidx library.

the solution is very easy: import correct activity!

from your MainActivity remove

import androidx.fragment.app.FragmentActivity

and add

import com.example.greetingcard.fragments.FragmentActivity

Answered By - Stappo