Why is the top toolbar not displayed in the application?

Question

Android

android studio.
And so the problem is that, as you can see from the picture, there should be a toolbar, but it is not in reality. I noticed the loss when I was writing Java application code. When removing the code, the toolbar is not returned. I did not touch anything in the parameter files to intentionally disable the toolbar. Only EditText hangs.
The situation is the same without the emulator - on a regular device.
Java code cut. And so and so the same thing, but the limit swears.

package myrause.mrconnect;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.Socket;
import java.util.Calendar;
import java.util.Enumeration;
import java.util.StringTokenizer;
import java.util.regex.Pattern;

public class main extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        send = (Button) findViewById(R.id.action_send);
        console = (Button) findViewById(R.id.action_console);
        delete = (Button) findViewById(R.id.action_delete);
        editText = (EditText) findViewById(R.id.editText);
        
        //IpV4();
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }
}

menu_main.xml

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item android:id="@+id/action_send"
        android:title="SEND"
        android:orderInCategory="102"
        app:showAsAction="always"
        android:icon="@android:drawable/ic_menu_send" />

    <item android:id="@+id/action_console"
        android:title="CONSOLE"
        android:orderInCategory="101"
        app:showAsAction="always"
        android:icon="@android:drawable/ic_menu_sort_by_size"/>

    <item android:id="@+id/action_delete"
        android:title="DELETE"
        android:orderInCategory="100"
        app:showAsAction="always"
        android:icon="@android:drawable/ic_menu_close_clear_cancel"/>
</menu>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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="myrause.mrconnect.main">
    <EditText   android:layout_height="fill_parent"
        android:layout_width="fill_parent"
        android:id="@+id/editText"
        android:gravity="top|left"
        android:inputType="textMultiLine" />

</android.support.constraint.ConstraintLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="myrause.mrconnect">
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".main">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

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

</manifest>

As you can see, I did little, but the jamb appeared.
Could this be an IDE, Windows and components issue when compiling? Have you ever experienced this? What do you think to do?

Answer 1

Add Toolbar to your markup file (activity_main.xml) and inherit AppTheme from any theme with NoActionBar