Does my app lack of something?

[vuquanghoang]

I want to learn about exlicit intent in Android, I just creat a new project in Eclipse with some following files:

1. 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" >

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:layout_marginTop="47dp"
            android:text="@string/main" />

        <EditText
            android:id="@+id/editText1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_alignParentTop="true"
            android:ems="10"
            android:hint="@string/main_writeSomething" >

            <requestFocus />
        </EditText>

    </RelativeLayout>

-------------------------------------------------------------
2. Activity_main.java

package com.example.myfirstapplication;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.support.v4.app.NavUtils;

public class MainActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        final EditText et = (EditText) findViewById(R.id.textView1);
        Button b = (Button) findViewById(R.id.button1);
        b.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, Second.class);
                intent.putExtra("thetext", et.getText());
                startActivity(intent);
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }


}

-------------------------------------------------------------
3. Second.java

 package com.example.myfirstapplication;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class Second extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.second);

        TextView tv = (TextView) findViewById(R.id.textView1);
        tv.setText(getIntent().getExtras().getString("thetext"));
    }
}

-------------------------------------------------------------
4. second.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/editText1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:ems="10" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="" />

</LinearLayout>

-------------------------------------------------------------
5.AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.myfirstapplication"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="15" />

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

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
             android:name=".Second"
             android:label="@string/app_name" 
          />
    </application>

</manifest>

I run the first activity normally, but when I have finished type something into the text field and click "go the the second activity", it display error: The application MyFirstApplication (process com.example.myfirstapplication) has stopped unexpectedly. Please try again. I don't know why. I have already declare all of actitivity in the manifest file. Please help me discorver the error :(