Basic steps to write an Activity:
1. Define a subclass of the Activity class, SecondActivity
2. Configure the components defined in ActivityManifest.xml
3. Define the layout file activity_second.xml
4. Rewrite Activity's onCreate() to load the layout file
Start an Activtiy
General startup:
Start with callback:
How to carry extra data
intent.putExtra(name,value)
How to get carry extra data
xxx.intent.getxxxExtra(name)
how to get started intent
Intent getIntent()
end an Activity
general end
finish（）
end with result
setResult(int resultCode , Intent data)
finish()
Activity life cycle and state
Activity的TaskStack
In Activity, the system uses the taskStack structure to store and manage the Activity objects that are started.
When an application starts, the system will create a corresponding taskStack for it to store and manage the Activity object of the application
Only the Activity at the top of the top task stack can be displayed in the window
Activity的launchMode
standard:
Standard mode, a new instance is generated each time the startActivity() method is called
singleTop
If there is already an instance at the top of the Activity stack, no new instance will be created
If it is not at the top of the stack, a new instance will be created
singleTask
There is only one instance, by default in the current Task
singleInstance
There is only one instance, a new booth will be created when it is created, and there can be no other objects in this stack
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call text code
MainActivity:
private EditText et_main_num;
private EditText et_main_sms;private Button btn_main_call;
private Button btn_main_send;
protected void onCreate(Bundle savedInstanceState){
super.onCreate (savedInstanceState);
setContentView(R.layout.activity_main);
//Initialize the control object. There are many button settings on the page to monitor
et_main_num=(EditText) findViewById(R.id.et_main_num);
et_main_sms=(EditText) findViewById(R.id.et_main_sms);
btn_main_call=(Button) findViewById(R.id.btn_main_call);
btn_main_send=(Button) findViewById(R.id.btn_main_send);
//Set the click listener for the button
btn_main_call.setOnClickListener(onClickListener);
btn_main_send.setOnClickListener(onClickListener);
//Set long press click listener
btn_main_call.setOnLongClickListener(this);
btn_main_send.setOnLongClickListener(this);
}
//click listener
private OnClickListener onClickListener=new View.OnClickListener() {
public void onClick(View v){
if (v==btn_main_call){//Call
//1. Create Intent Implicit
String action="android.intent.action.DIAL";
Intent intent=new Intent(action);
//2. Carry data
String number=et_main_num.getText().toString().trim();
intent.setData(Uri.parse("tel:"+number));
//3. Start Activity
startActivity(intent);
}else if(v==btn_main_send){//Send SMS
Intent intent = new Intent(Intent.ACTION_SENDTO);//Create an Intent object
String number= btn_main_send.getText().toString().trim(); //carry data
String sms=et_main_sms.getText().toString().trim();
intent.setData(Uri.parse("smsto:"+number));//Set data
intent.putExtra("sms_body", sms);
startActivity(intent); //Start Activity
}
}
}；
//Long press click listener
public boolean onLongClick(View v){
if (v==btn_main_call) {
Intent intent = new Intent(Intent.ACTION_CALL);
String number=et_main_num.getText().toString().trim();
intent.setData(Uri.parse("tel:"+number));
startActivity(intent);
}else if(v==btn_main_send){
SmsManager smsmanager = SmsManager.getDefault();
String number= btn_main_send.getText().toString().trim();//carry data
String sms=et_main_sms.getText().toString().trim();
//send messages
smsmanager.sendTextMessage (number, null, sms, null, null);
}
return true;//Indicates that this event has been consumed, and the click event will not be triggered again
}
}
activit_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<!--
LinearLayout中的 android:orientation="horizontal" 水平排列
android:orientation="vertical" 垂直排列
-->
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/tel" />
<EditText
android:id="@+id/et_main_num"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/input_num"
>
</EditText>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/sms" />
<EditText
android:id="@+id/et_main_sms"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="@string/input_content"
>
</EditText>
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
>
<Button
android:id="@+id/btn_main_call"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/call"
/>
<Button
android:id="@+id/btn_main_send"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/send"
/>
</LinearLayout>
</LinearLayout>
Strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">App02_Call_SMS</string>
<string name="hello_world">Hello world!</string>
<string name="tel">电话号码：</string>
<string name="sms">短信内容：</string>
<string name="call">打电话</string>
<string name="send">发短信</string>
<string name="input_num">请输入号码</string>
<string name="input_content">请输入短信内容</string>
</resources>