android学习历程4--activity

1.Activity的主要作用

 

 

2.创建一个Activity的方法

          创建Activity方法：

           1>.一个Activity就是一个类，并且要继承自Activity

           2>.需要复写onCreate方法(在Activity第一次运行的时候就会调用onCreate方法）

 

 

 

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

           public class activity_02 extends Activity{
                     private TextView myTextView = null;
                     protected void onCreate(Bundle savedInstanceState) {
                                super.onCreate(savedInstanceState);
                                 setContentView(R.layout.textview);
                                Intent intent = getIntent();
                               String value = intent.getStringExtra("myBtnClick");
                              myTextView = (TextView)findViewById(R.id.myTextView);
                              //myTextView.setText(R.string.app_text);
                               myTextView.setText(value);
                       }
 

}

 

 

 

           3>.每一个Activity都需要在AndroidManifest.xml文件中进行配置

           4>.为Activity添加必要的控件

 

 

 

3.在AndroidManifest.xml文件中注册应用Activity的方法

                 <activity android:name=".activity_02"
                                  android:label="@string/app_text">
                 </activity>

 

4.在Activity当中添加控件的方法

                 设置res/layout/*.xml

                  <?xml version="1.0" encoding="utf-8"?>
                   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                  android:orientation="vertical"
                  android:layout_width="fill_parent"
                  android:layout_height="fill_parent"
                  >
                <Button
                      android:id="@+id/myButton"
                      android:layout_width="fill_parent"
                      android:layout_height="wrap_content"
                 />
                </LinearLayout>