Android学习笔记01

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Mars老师讲的很好，不记笔记会忘的

从第四讲开始吧

创建Activity要点

1.一个Activity就是一个类，并且这个类要继承Activity

2.需要复写onCreate方法

3.每一个Activity都需要在AndroidMainfest.xml中配置

4.为Activity添加必要的控件

添加控件步骤

先在activity_main.xml中添加代码，注意控件的android:id属性

<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" >    <TextView        android:id="@+id/mytextview"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:layout_centerVertical="true"        tools:context=".MainActivity" />    <Button android:id="@+id/mybutton"         android:layout_width="wrap_content"android:layout_height="wrap_content"/></RelativeLayout>

保存好后会在R.java下生成相应的代码

/* 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 fengda.activity01;public final class R {    public static final class attr {    }    public static final class drawable {        public static final int ic_action_search=0x7f020000;        public static final int ic_launcher=0x7f020001;    }    public static final class id {        public static final int menu_settings=0x7f070002;        public static final int mybutton=0x7f070001;        public static final int mytextview=0x7f070000;    }    public static final class layout {        public static final int activity_main=0x7f030000;    }    public static final class menu {        public static final int activity_main=0x7f060000;    }    public static final class string {        public static final int app_name=0x7f040000;        public static final int hello_world=0x7f040001;        public static final int menu_settings=0x7f040002;        public static final int title_activity_main=0x7f040003;    }    public static final class style {        public static final int AppTheme=0x7f050000;    }}

回到Activity.java中

使用findViewById来寻找到textview及button

package fengda.activity01;import fengda.activity01.R.id;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.widget.TextView;import android.widget.Button;public class MainActivity extends Activity {    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);                TextView myTextView = (TextView) findViewById(id.mytextview);        Button myButton = (Button) findViewById(id.mybutton);        myTextView.setText("哈哈，我出来了！");        myButton.setText("点我啊！");    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        getMenuInflater().inflate(R.menu.activity_main, menu);        return true;    }}

运行，效果如下图,才刚学，能显示出效果就行了，布局知识还没学到