01_04_Activity初步

01_04_Activity初步
1、Activity的主要作用
2、创建一个Activity的方法
3、在AndroidManifest.xml文件当中注册应用Activity的方法
4、在Activity中添加控件的方法


创建Activity的要点
        1、一个Activity就是一个类，并且这个类要继承Activity类（来源自android.jar这个包）
        2、需要复写onCreate方法（一个Activity运行时，首先调用OnCreate方法，由Android的操作系统调用的）
        3、每一个Activity必须在AndroidManifest.xml中注册并配置
        4、为Activity添加必要的控件

创建Activity的要点
        1、一个Activity就是一个类，并且这个类要继承Activity类（来源自android.jar这个包）
        2、需要复写onCreate方法（一个Activity运行时，首先调用OnCreate方法，由Android的操作系统调用的）

//Activity01.java
package com.lwb.myactivity_01;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.Button;
import android.widget.TextView;
/*
 * 创建Activity的要点
 * 1、一个Activity就是一个类，并且这个类要继承Activity类（来源自android.jar这个包）
 * 2、需要复写onCreate方法（一个Activity运行时，首先调用OnCreate方法，由Android的操作系统调用的）
 * 3、每一个Activity必须在AndroidManifest.xml中注册并配置
 * 4、为Activity添加必要的控件
 * */
public class Activity01 extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState); //首先，调用父类的onCreate()方法
        setContentView(R.layout.activity_activity01); //设置这个Activity的布局文件为activity_activity01
        TextView myTextView=(TextView)findViewById(R.id.myTextView);//通过控件的Id找到控件
        Button myButton =(Button)findViewById(R.id.myButton);
        myTextView.setText("我的第一个TextView");
        myButton.setText("我的第一个Button"+"\n"+"test");


    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity01, menu);
        return true;
    }

}

        3、每一个Activity必须在AndroidManifest.xml中注册并配置
       

<?xml version="1.0" encoding="utf-8"?>
<!--AndroidManifest.xml  myActivity_01 Manifest.xml -->
<manifest xmlns:android=""

    package="com.lwb.myactivity_01"
    android:versionCode="1"
    android:versionName="1.0" >
      <!--包名  package="com.lwb.myactivity_01"-->
    <uses-sdk
        android:minSdkVersion="10"
        android:targetSdkVersion="17" />
        <!--SDK 最低版本10即 2.3.3  -->
        <!--SDK 最高版本17  -->

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <!--应用程序的图标 -->
        <!--应用程序的标签 -->
        <activity
            android:name="com.lwb.myactivity_01.Activity01"

            android:label="@string/app_name" >
             <!--Activity名  -->
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
             <!-- 某个应用程序中，配置了intent-filter，表这个Activity是程序中第一个运行的Activity -->
        </activity>
    </application>

</manifest>

        4、为Activity添加必要的控件

<!-- activity_activity01.xml -->
 <!-- 布局，通常一个Activity对应着一个布局，当然，可一个多个Activity使用一个布局 -->
<!--
线性布局LinearLayout，android:orientation="vertival"
 绝对布局AbsoluteLayout、
 相对布局RelativeLayout
 框架布局FranworkLayout
 表格布局TableLayout-->
<LinearLayout xmlns:android=""
    xmlns: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=".Activity01" >

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

    <Button
        android:id="@+id/myButton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />

</LinearLayout>

R.java文件如下：

/* AUTO-GENERATED FILE.  DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found.  It
 * should not be modified by hand.
 */

package com.lwb.myactivity_01;

public final class R {
    public static final class attr {
    }
    public static final class dimen {
        /**  Default screen margins, per the Android Design guidelines.

         Customize dimensions originally defined in res/values/dimens.xml (such as
         screen margins) for sw720dp devices (e.g. 10" tablets) in landscape here.

         */
        public static final int activity_horizontal_margin=0x7f040000;
        public static final int activity_vertical_margin=0x7f040001;
    }
    public static final class drawable {
        public static final int ic_launcher=0x7f020000;
    }
    public static final class id {
        public static final int action_settings=0x7f080002;
        public static final int myButton=0x7f080001;
        public static final int myTextView=0x7f080000;
    }
    public static final class layout {
        public static final int activity_activity01=0x7f030000;
    }
    public static final class menu {
        public static final int activity01=0x7f070000;
    }
    public static final class string {
        public static final int action_settings=0x7f050001;
        public static final int app_name=0x7f050000;
        public static final int hello_world=0x7f050002;
    }
    public static final class style {
        /**
        Base application theme, dependent on API level. This theme is replaced
        by AppBaseTheme from res/values-vXX/styles.xml on newer devices.


            Theme customizations available in newer API levels can go in
            res/values-vXX/styles.xml, while customizations related to
            backward-compatibility can go here.


        Base application theme for API 11+. This theme completely replaces
        AppBaseTheme from res/values/styles.xml on API 11+ devices.

 API 11 theme customizations can go here.

        Base application theme for API 14+. This theme completely replaces
        AppBaseTheme from BOTH res/values/styles.xml and
        res/values-v11/styles.xml on API 14+ devices.

 API 14 theme customizations can go here.
         */
        public static final int AppBaseTheme=0x7f060000;
        /**  Application theme.
 All customizations that are NOT specific to a particular API-level can go here.
         */
        public static final int AppTheme=0x7f060001;
    }
}

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