activity_main.xml: MainActivity.java: package com.example.apppp; import androidx.appcompat.app.AppCompatActivity; import android.os.Bundle; public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } }   ---- when i am running this file ,it shows  Could not identify launch activity: Default Activity not found Error while Launching activity Failed to launch an application on all devices whats this wrong and how can i fix it .

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"
tools:layout_editor_absoluteX="-10dp"
tools:layout_editor_absoluteY="-74dp">

<ImageView
android:id="@+id/imageView2"
android:layout_width="140dp"
android:layout_height="100dp"
android:contentDescription="TODO"
android:src="@drawable/caa"
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="0.283" />

<TextView
android:id="@+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="48dp"
android:text="Email"
android:textColor="@color/black"
android:textSize="16sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/editTextTextEmailAddress"
app:layout_constraintHorizontal_bias="0.881"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.517" />

<EditText
android:id="@+id/editTextTextEmailAddress"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:hint="someone@example.com"
android:inputType="textEmailAddress"
android:minHeight="48dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.726"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.499" />

<EditText
android:id="@+id/editTextTextPassword2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Password"
android:inputType="textPassword"
android:minHeight="48dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.726"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.6" />

<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Password"
android:textColor="@color/black"
android:textSize="16sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toStartOf="@+id/editTextTextPassword2"
app:layout_constraintHorizontal_bias="0.702"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.598" />

<Button
android:id="@+id/button2"
android:layout_width="193dp"
android:layout_height="48dp"
android:background="#FF0000"
android:text="Login"
android:textColor="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.669"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.69"
tools:ignore="TextContrastCheck" />

<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Fill your content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.956" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java:

package com.example.apppp;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

}
}

----

when i am running this file ,it shows 

Could not identify launch activity: Default Activity not found
Error while Launching activity
Failed to launch an application on all devices

whats this wrong and how can i fix it .