The first line of code: Android Learning Note: Activity & Intent

The first line of code: Android Guo Lin (2.2) basic usage of activity

• Hide title bar
  • Configured in Androidmanifest.xml, as a global configuration, takes effect within all activity scopes
    • Android:theme= "@android: Style/theme.notitlebar"
  • Configured in code, the method must be called before Setcontentview (), only if the current activity is active
    • Requestwindowfeature (Window.feature_no_title);
  • Set in Style.xml

2.3 Intent Application Scenarios

• Activity
• Service
• Broadcastreceiver

2.3.1 Explicit Intent

• Intent Intent = new Intent (currentactivity.this, Nextactivity.class);
• StartActivity (Intent);
• Explicitly specify the next Activity

2.3.2 Implicit Intent code creates intent objects without explicitly pointing to specific activity. The action/category/data of the intent object is set, and when startactivity (intent) is called, the system calls the Androidmanifest.xml registered in activity,< The action/category/data specified in the intent-filter> must be exactly the same as the code's settings.

• Action
  • Intent Intent = new Intent (Intent.action_view);
  • The Action_view here is the action. Each intent object has only one action, which can be customized
  • Intent.action_view Response to open browser action
  • Intent.action_dial response call "dialing" action
• Category
  • Intent.addcategory ("My_category");
  • Add category with Addcategory (), each intent object can be set to multiple category , customizable
• Data
  • More precisely specify the type of intent the activity can respond to, setting multiple data
  • Android:scheme
  • Android:host
  • Android:mimetype
  • etc.

Transfer data between 2.3.4 activity (set activity A to B pass data)

• is passed through intent in the form of key-value, such as the HashMap object
  • Intent.putextra ("My_key", value);
• a replace startactivity () with Startactivityforresult () and pass in Requestcode Identity (flag)
  • Startactivityforresult (Intent, Requestcode) when the data returned by the other activity is received as a;
• b obtains data by obtaining the Intent object passed by a
  • Intent Intent = Getintent ();
  • String data = Intent.getstringextra ("My_key");
• If B is going to return data to a, you need to add ReturnCode
  • Intent Intent = new Intent ();
  • Intent.putextra (key, value);
  • Setresult (RESULT_OK, intent);
  • finish ();
• A processes data that is returned by B in Onactivityresult ()
  • using a switch statement based on Requestcode
  • can root According to ResultCode ( result_ok/result_cancel)
• B Pass data when you click the back key
  • overwrite Onbackpresse D ();
  • super.onbackpressed (); Be sure to comment out or put at the end, otherwise you will return directly in this step

The first line of code: Android Learning Note: Activity & Intent