title: android.support.v7.widget.AppCompatTextView cannot be cast to android.widget.RelativeLayout
body: <p>I am learning Android with <a href="http://developer.android.com/index.html" rel="noreferrer">http://developer.android.com/index.html</a>, but when I reach <a href="http://developer.android.com/training/basics/firstapp/starting-activity.html" rel="noreferrer">http://developer.android.com/training/basics/firstapp/starting-activity.html</a> Display the Message section, point 6 I have an error </p>
  
  <pre><code>android.support.v7.widget.AppCompatTextView cannot be cast to android.widget.RelativeLayout 
  </code></pre>
  
  <p>I did everything step by step like it was in tutorial. So why it doesn't work?</p>
  
  <pre><code>DisplayMessageActivity.java
  
      package com.example.flover.hellloworld;
  
      import android.content.Intent;
      import android.os.Bundle;
      import android.support.v7.app.AppCompatActivity;
      import android.view.Menu;
      import android.view.MenuItem; 
      import android.widget.RelativeLayout;
      import android.widget.TextView;
  
      public class DisplayMessageActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
  
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_display_message);
  
  
          Intent intent = getIntent();
          String message = intent.getStringExtra(MyActivity.EXTRA_MESSAGE);
          TextView textView = new TextView(this);
          textView.setTextSize(40);
          textView.setText(message);
  
          RelativeLayout layout = (RelativeLayout) findViewById(R.id.content);
          layout.addView(textView);
      }
  
      @Override
      public boolean onCreateOptionsMenu(Menu menu) {
          // Inflate the menu; this adds items to the action bar if it is present.
          getMenuInflater().inflate(R.menu.menu_display_message, menu);
          return true;
      }
  
      @Override
      public boolean onOptionsItemSelected(MenuItem item) {
          // Handle action bar item clicks here. The action bar will
          // automatically handle clicks on the Home/Up button, so long
          // as you specify a parent activity in AndroidManifest.xml.
          int id = item.getItemId();
  
          //noinspection SimplifiableIfStatement
          if (id == R.id.action_settings) {
              return true;
          }
  
          return super.onOptionsItemSelected(item);
      }
  }
  </code></pre>
  
  <p>activity_display_message.xml</p>
  
  <pre><code>&lt;RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context="com.example.flover.hellloworld.DisplayMessageActivity"&gt;
  
      &lt;TextView
          android:id="@+id/content"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          &gt;&lt;/TextView&gt;
  
  &lt;/RelativeLayout&gt;
  </code></pre>