Why, after deleting the button in the Android Android studio’s layout, does it still see it?

Question

I removed the signUp button from my layout, android studio does not see it, but when the application starts, it appears.

<?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:backgroundTint="@color/colorPrimaryDark"
    android:layout_height="match_parent"
    tools:context=".home.MainActivity">

    <FrameLayout
        android:id="@+id/nav_host_fragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toTopOf="@id/roundLayout"/>

    <com.github.florent37.shapeofview.shapes.RoundRectView
        android:id="@+id/roundLayout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginBottom="8dp"
        android:layout_marginLeft="8dp"
        android:layout_marginRight="8dp"
        android:elevation="12dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:shape_roundRect_bottomLeftRadius="22dp"
        app:shape_roundRect_bottomRightRadius="22dp"
        app:shape_roundRect_topLeftRadius="8dp"
        app:shape_roundRect_topRightRadius="8dp">

        <com.ismaeldivita.chipnavigation.ChipNavigationBar
            android:id="@+id/chipNavigationMenu"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_gravity="bottom"
            android:background="@color/white"
            app:cnb_menuResource="@menu/bottom_menu"/>

    </com.github.florent37.shapeofview.shapes.RoundRectView>

</androidx.constraintlayout.widget.ConstraintLayout>

Here is the class code that calls activity_home. After I transferred the activity_home code to another layout, it worked, but immediately hung again and did not change.

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.os.PersistableBundle
import androidx.fragment.app.Fragment
import cheprasov.egor.cchat.R
import cheprasov.egor.cchat.fragments.favorite.favorites
import cheprasov.egor.cchat.fragments.home.homeFragment
import cheprasov.egor.cchat.fragments.settings.settings
import com.google.firebase.auth.FirebaseAuth
import com.ismaeldivita.chipnavigation.ChipNavigationBar

class MainActivity : AppCompatActivity() {

    private lateinit var auth: FirebaseAuth
    private lateinit var mAthListner: FirebaseAuth.AuthStateListener
    private lateinit var menu: ChipNavigationBar
    private var fragment: Fragment? = null
    private lateinit var fragmentsHome: Fragment
    private lateinit var fragments: Fragment

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

        if(fragment== null){
            val transaction = supportFragmentManager.beginTransaction()
            fragmentsHome = homeFragment()
            transaction.replace(R.id.nav_host_fragment,fragmentsHome)
            transaction.commit()
        }
        menu.setOnItemSelectedListener { id ->
            val option = when (id){
                R.id.home -> {
                    fragments = fragmentsHome
                    setFragment(fragments)
                }
                R.id.favorited -> {
                    fragments = favorites()
                    setFragment(fragments)
                }
                R.id.settings ->{
                    fragments = settings()
                    setFragment(fragments)
                }
                else -> finish()
            }
        }
    }

    private fun setFragment(fragment: Fragment){
        val transaction = supportFragmentManager.beginTransaction()
        transaction.replace(R.id.nav_host_fragment,fragment)
        transaction.commit()
    }


    private fun init(){
        auth = FirebaseAuth.getInstance()
        menu = findViewById(R.id.chipNavigationMenu)
    }

    override fun onStop() {
        super.onStop()
    }

    override fun onPause() {
        super.onPause()
    }

    override fun onRestoreInstanceState(savedInstanceState: Bundle) {
        super.onRestoreInstanceState(savedInstanceState)
    }

    override fun onResume() {
        super.onResume()
    }

    override fun onSaveInstanceState(outState: Bundle, outPersistentState: PersistableBundle) {
        super.onSaveInstanceState(outState, outPersistentState)
    }

    override fun onBackPressed() {
        super.onBackPressed()
        moveTaskToBack(true)
    }

    private fun signOut(){
        auth.signOut()
    }
}

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Answer 1

Quickest solution

Try restarting the app on the emulator using the run or debug icon on Android Studio.

Cleaner solution

1. Delete the app from emulator.
2. Delete the apk files created in the app/build/outputs/apk/debug/app-debug.apk

Usually this problem happens in either of the following cases

1. When App is not rerun, only the layout is changed
2. When you use Instant run, sometimes it might not re-render instantly, It takes a few seconds..