Apps android application stopps

[oriz]

Hello i started learning android from that site Starting Another Activity | Android Developers

and whati did doesnt working.
here is the files

activity_main XML

        <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    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/content"
        android:layout_width="220dp"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send"
        android:onClick="SendMessage"/>
</LinearLayout>

MainActivity:

         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;
    }
    public void SendMessage(View view)
    {
        Intent i = new Intent (this,Another.class);
        EditText t = (EditText) findViewById(android.R.id.content);
        String s = t.getText().toString();
        i.putExtra(EXTRA_MESSAGE, s);
        startActivity(i);
    }

Another

            protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Intent i = getIntent();
        String s = i.getStringExtra(MainActivity.EXTRA_MESSAGE);
        setContentView(R.layout.activity_another);
       
        TextView t = new TextView(this);
        t.setTextSize(40);
        t.setText(s);
        setContentView(t);
    }

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

and the manifest

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

    <uses-sdk
        android:minSdkVersion="4"
        android:targetSdkVersion="18" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.first.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.first.Another"
            android:label="@string/title_activity_another" >
        </activity>
    </application>

</manifest>

When i am pushing send buttton the program get terminated and i dont know why
please help me.