Soy nuevo en el mundo del desarrollo de Android y he creado una aplicación simple "Hello World". Primero, la actividad solicita un texto. Cuando se hace clic en el botón "Ir", la aplicación inicia la segunda actividad que muestra el texto de entrada.

Si hago clic en el botón INICIO y luego en el ícono de la aplicación, la aplicación inicia la primera actividad nuevamente, pero si presiono el botón de inicio y hago clic en el ícono de la barra de "Aplicaciones recientes", se reanuda la aplicación donde lo dejé.

¿Cómo evito esto?

Necesito que mi aplicación se reanude incluso si se hace clic en el icono del iniciador.

MainActivity.java,

package com.example.myfirstandroidapp;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;

public class MainActivity extends Activity {
  public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
  }
  /** Called when the user clicks the Send button */
  public void sendMessage(View view){
    // Do something in response to button
    Intent intent = new Intent(this, DisplayMessageActivity.class);
    EditText editText = (EditText) findViewById(R.id.txtName);
    String message = editText.getText().toString();
    intent.putExtra(EXTRA_MESSAGE, message);
    startActivity(intent);
  }
}

DisplayActivity.java,

package com.example.myfirstandroidapp;

import android.annotation.TargetApi;
import android.app.Activity;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class DisplayMessageActivity extends Activity {

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    // Get the message from the intent
    Intent intent = getIntent();
    String message = intent.getStringExtra(MainActivity.EXTRA_MESSAGE);

    // Create the text view
    TextView textView = new TextView(this);
    textView.setTextSize(40);
    textView.setText(message);

    // Set the text view as the activity layout
    setContentView(textView);

    // Show the Up button in the action bar.
    setupActionBar();
  }

  /**
   * Set up the {@link android.app.ActionBar}, if the API is available.
   */
  @TargetApi(Build.VERSION_CODES.HONEYCOMB)
  private void setupActionBar() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
      getActionBar().setDisplayHomeAsUpEnabled(true);
    }
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.display_message, menu);
    return true;
  }

  @Override
  public void onDestroy(){
    super.onDestroy();
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case android.R.id.home:
      // This ID represents the Home or Up button. In the case of this
      // activity, the Up button is shown. Use NavUtils to allow users
      // to navigate up one level in the application structure. For
      // more details, see the Navigation pattern on Android Design:
      //
      // http://developer.android.com/design/patterns/navigation.html#up-vs-back
      //
      NavUtils.navigateUpFromSameTask(this);
      return true;
    }
    return super.onOptionsItemSelected(item);
  }


}

activity_main.xml,

    <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=".MainActivity" >

        <EditText
            android:id="@+id/txtName"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="70dp"
            android:ems="10" >

            <requestFocus />
        </EditText>

        <Button
            android:id="@+id/btnGo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignBottom="@+id/txtName"
            android:layout_alignParentRight="true"
            android:onClick="sendMessage"
            android:text="Go!" />

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignLeft="@+id/txtName"
            android:layout_alignParentTop="true"
            android:layout_marginTop="18dp"
            android:text="Please input your name:"
            android:textAppearance="?android:attr/textAppearanceMedium" />

    </RelativeLayout>

activity_display_message.xml,

<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=".DisplayMessageActivity" >

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />



</RelativeLayout>

AndroidManifest.xml,

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myfirstandroidapp"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="9"
        android:targetSdkVersion="10" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.myfirstandroidapp.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name="com.example.myfirstandroidapp.DisplayMessageActivity"
            android:label="@string/title_activity_display_message"
            android:parentActivityName="com.example.myfirstandroidapp.MainActivity" >
            <meta-data
                android:name="android.support.PARENT_ACTIVITY"
                android:value="com.example.myfirstandroidapp.MainActivity" />
        </activity>
    </application>

</manifest>