空的安卓工程添加activity

1.编写类继承activity，并重写onCreate方法

package org.tonny;

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

public class FirstActivity extends Activity
{

	@Override
	protected void onCreate(Bundle savedInstanceState)
	{
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.layout_first);
	}

}

2.编写布局文件

<?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" >

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Hello"/>

</LinearLayout>

3.修改清单文件

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

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="21" />

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

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

4.开启即可运行