Can't view another activity in kotlin

Question

It moves to the activity but I get an empty page

MainActivit.kt

This is the block I use to move

binding.fab2.setOnClickListener {
            val intent = Intent(this, InfoActivity::class.java)
            startActivity(intent)
        }

The other activity

I removed the package

package ...

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle

import com.m.anwer.astudy.databinding.ActivityInfoBinding

public class InfoActivity : AppCompatActivity() {

    private var _binding: ActivityInfoBinding? = null

    

    private val binding: ActivityInfoBinding

      get() = checkNotNull(_binding) { "Activity has been destroyed" }

    

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        _binding = ActivityInfoBinding.inflate(layoutInflater)

        setContentView(binding.root)

        

    }

    

    override fun onDestroy() {

        super.onDestroy()

        _binding = null

    }


}

activity_info.xml

All seems good

<?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=".InfoActivity">

    

    <com.google.android.material.appbar.AppBarLayout

        android:id="@+id/appbar"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:theme="@style/ThemeOverlay.MaterialComponents.Dark.ActionBar"

        app:layout_behavior="com.google.android.material.appbar.AppBarLayout$Behavior">

        <com.google.android.material.appbar.MaterialToolbar

            android:id="@+id/toolbar"

            android:layout_width="match_parent"

            android:layout_height="?attr/actionBarSize"

            app:popupTheme="@style/ThemeOverlay.MaterialComponents.Light" />

        

        <TextView

            android:id="@+id/tv1"

            android:layout_height="wrap_content"

            android:layout_width="wrap_content"

            android:text="Welcome"

            android:textSize="18sp"

            android:textStyle="bold"

            android:layout_margin="16dp"

            app:layout_constraintRight_toRightOf="parent"

            app:layout_constraintTop_toTopOf="parent" />

    </com.google.android.material.appbar.AppBarLayout>

</androidx.constraintlayout.widget.ConstraintLayou
t>

Manifest

I added the another activity manually

<?xml version="1.0" encoding="utf-8"?>

<manifest 

    xmlns:android="http://schemas.android.com/apk/res/android">

    <application 

        android:allowBackup="true" 

        android:icon="@drawable/graduate_hat" 

        android:roundIcon="@drawable/graduate_hat" 

        android:label="@string/app_name" 

        android:supportsRtl="true" 

        android:theme="@style/AppTheme">

        <activity 

            android:name=".MainActivity" 

            android:exported="true">

            <intent-filter>

                <action 

                    android:name="android.intent.action.MAIN" />

                <category 

                    android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

        <activity android:name=".InfoActivity" />

    </application>

</manifest>

All seems good but I don't know what is wrong

I have tried it without binding and the same problem. Tried to move to MainActivity from the same Activity and worked

Answer 1

Looks like the activity_info.xml nesting might be the problem.

You have

ConstraintLayout
    AppBarLayout
        MaterialToolBar
        TextView

Your Textview has constraint layout attributes but isn't in the constraint layout. The AppBarLayout doesn't have constraint layout attributes.

I think you're looking for something like

CoordinatorLayout
    AppBarLayout
        MaterialToolbar
    ConstraintLayout
        TextView (or other content)

AppBarLayout should cooperate with the CoordinatorLayout (for expand/collapse etc.) and the TextView should be in the main content area (the ConstraintLayout)

For example:

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2023 Google LLC.
     SPDX-License-Identifier: Apache-2.0
-->
<androidx.coordinatorlayout.widget.CoordinatorLayout 
    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:fitsSystemWindows="true"
    tools:context=".InfoActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:fitsSystemWindows="true">

        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize" />

    </com.google.android.material.appbar.AppBarLayout>

    <androidx.constraintlayout.widget.ConstraintLayout     
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">

        <TextView
            android:id="@+id/tv1"
            android:layout_height="wrap_content"
            android:layout_width="wrap_content"
            android:text="Welcome"
            android:textSize="18sp"
            android:textStyle="bold"
            android:layout_margin="16dp"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />

    </androidx.constraintlayout.widget.ConstraintLayout>
</androidx.coordinatorlayout.widget.CoordinatorLayout>