title: You must call removeView() on the child's parent first! How to get rid of this error?
body: <p>I have made this simple app that uses explicit intents to move from an activity to another. </p>
  
  <p><a href="https://i.stack.imgur.com/XSPLs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/XSPLs.png" alt="enter image description here"></a></p>
  
  <p>It works fine for all activities (e.g. move from <code>MainActivity</code> to <code>FamilyActivity</code>) but it doesn't wok when it comes to move from <code>MainActivity</code> to <code>NumbersActivity</code> and it show this <strong>LogCat</strong> : </p>
  
  <pre><code>09-05 08:04:02.518 26820-26820/com.example.android.miwok E/AndroidRuntime: FATAL EXCEPTION: main
                                                                         java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.miwok/com.example.android.miwok.NumbersActivity}: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
                                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2372)
                                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424)
                                                                             at android.app.ActivityThread.access$600(ActivityThread.java:162)
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
                                                                             at android.os.Handler.dispatchMessage(Handler.java:107)
                                                                             at android.os.Looper.loop(Looper.java:194)
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5400)
                                                                             at java.lang.reflect.Method.invokeNative(Native Method)
                                                                             at java.lang.reflect.Method.invoke(Method.java:525)
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:837)
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604)
                                                                             at dalvik.system.NativeStart.main(Native Method)
                                                                          Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
                                                                             at android.view.ViewGroup.addViewInner(ViewGroup.java:3430)
                                                                             at android.view.ViewGroup.addView(ViewGroup.java:3301)
                                                                             at android.view.ViewGroup.addView(ViewGroup.java:3246)
                                                                             at android.view.ViewGroup.addView(ViewGroup.java:3222)
                                                                             at com.example.android.miwok.NumbersActivity.onCreate(NumbersActivity.java:40)
                                                                             at android.app.Activity.performCreate(Activity.java:5122)
                                                                             at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
                                                                             at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2336)
                                                                             at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2424) 
                                                                             at android.app.ActivityThread.access$600(ActivityThread.java:162) 
                                                                             at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364) 
                                                                             at android.os.Handler.dispatchMessage(Handler.java:107) 
                                                                             at android.os.Looper.loop(Looper.java:194) 
                                                                             at android.app.ActivityThread.main(ActivityThread.java:5400) 
                                                                             at java.lang.reflect.Method.invokeNative(Native Method) 
                                                                             at java.lang.reflect.Method.invoke(Method.java:525) 
                                                                             at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:837) 
                                                                             at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:604) 
                                                                             at dalvik.system.NativeStart.main(Native Method) 
  </code></pre>
  
  <p><strong>MainActivty.java</strong></p>
  
  <pre><code>    package com.example.android.miwok;
  
  import android.app.Activity;
  import android.content.Intent;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.view.View;
  import android.widget.TextView;
  import android.widget.Toast;
  
  public class MainActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
  
          // Set the content of the view to use the activity main.xml
          setContentView(R.layout.activity_main);
  
          // Find the view that shows the numbers category
          //TextView numbers = (TextView)findViewById(R.id.numbers);
  
          // Find the view that shows the numbers category, then set a clickListener on it
          TextView numbers= (TextView)findViewById(R.id.family);
          numbers.setOnClickListener(new View.OnClickListener(){
              @Override
              public void onClick(View view) {
                  Intent i = new Intent(MainActivity.this, NumbersActivity.class);
                  startActivity(i);
              }
          });
  
          // Repeat the same for other categories
          TextView family= (TextView)findViewById(R.id.family);
          family.setOnClickListener(new View.OnClickListener(){
              @Override
              public void onClick(View view) {
                  Intent i = new Intent(MainActivity.this, FamilyMembersActivity.class);
                  startActivity(i);
              }
          });
  
          TextView colors = (TextView)findViewById(R.id.colors);
          colors.setOnClickListener(new View.OnClickListener(){
              @Override
              public void onClick(View view) {
                  Intent i = new Intent(MainActivity.this, ColorsActivity.class);
                  startActivity(i);
              }
          });
  
          TextView phrases = (TextView)findViewById(R.id.phrases);
          phrases.setOnClickListener(new View.OnClickListener(){
              @Override
              public void onClick(View view) {
                  Intent i = new Intent(MainActivity.this, PhrasesActivity.class);
                  startActivity(i);
              }
          });
      }
  }
  </code></pre>
  
  <p><strong>NumbersActivity.java</strong> </p>
  
  <pre><code>package com.example.android.miwok;
  
  import android.content.DialogInterface;
  import android.support.v7.app.AppCompatActivity;
  import android.os.Bundle;
  import android.util.Log;
  import android.view.View;
  import android.widget.LinearLayout;
  import android.widget.TextView;
  import android.widget.Toast;
  
  import java.util.ArrayList;
  
  public class NumbersActivity extends AppCompatActivity {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_numbers);
      }
  }
  </code></pre>
  
  <p><strong>MainActivity.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;LinearLayout 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"
      android:background="@color/tan_background"
      android:orientation="vertical"
      tools:context="com.example.android.miwok.MainActivity"&gt;
  
      &lt;TextView
          android:id="@+id/numbers"
          style="@style/CategoryStyle"
          android:background="@color/category_numbers"
          android:text="@string/category_numbers" /&gt;
  
      &lt;TextView
          android:id="@+id/family"
          style="@style/CategoryStyle"
          android:background="@color/category_family"
          android:text="@string/category_family" /&gt;
  
      &lt;TextView
          android:id="@+id/colors"
          style="@style/CategoryStyle"
          android:background="@color/category_colors"
          android:text="@string/category_colors" /&gt;
  
      &lt;TextView
          android:id="@+id/phrases"
          style="@style/CategoryStyle"
          android:background="@color/category_phrases"
          android:text="@string/category_phrases" /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p><strong>NumbersAtivity.xml</strong></p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &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"
      android:paddingBottom="@dimen/activity_vertical_margin"
      android:paddingLeft="@dimen/activity_horizontal_margin"
      android:paddingRight="@dimen/activity_horizontal_margin"
      android:paddingTop="@dimen/activity_vertical_margin"
      tools:context="com.example.android.miwok.NumbersActivity"&gt;
  &lt;/RelativeLayout&gt;
  </code></pre>