Head Fisrt Android Development读书笔记（7）Multi Screep Apps

Screen Navigation

1.Create a new Activity and configure it to use a new Layout

2.Create an Intent

3.Call startActivity or startActvityForResult to launch a new screen

4.onActivityResult to deal with data result from launched activity

 

New Menu Steps

1.Create a new menu XML file from the new XML file wizard

2.Add menu items

3.Inflate the menu using the MenuInflater in the onCreateOptionsMenu method in your activity /// getMenuInflater();

4.Process the menu action in onMenuItemSelected in your activity.

startActivity & Intent

Android maintains a stack of Activities your app has started, beginning with the first Activity in your app. As you start new Activtities like you did with the time entry screen, it's automatically added to the back of Activities.

Intent is an abstracted description of an operation to be performed. It can be used with startActivtiy to launch an Activity

Intent intent = new Intent(this, AddTimeActivity.class); // from , to

Intent intent = getIntent() calling getIntent() retrieves the starting intent from a running Activity.

intent.putExtra("time", ....)

this.setResult(RESULT_OK, intent);

call finish() to complete a screen and automatically display the previous screen on the back stack

startActivityForResult

EditText

use EditText for text entry

  <EditText ... />

 

Menu

/res/menu for menu layout

activity onCreateOptionsMenu()

public void onCreateOptionsMenu(Menu m) {

 super.onCreateOptionsMenu(m);

 MenuInflater menuInflater = getMenuInflatter();

 menuInflater.inflate(R.menu.time_list_menu, menu);

}

capture the menu action: onMenuItemSelected

Adapter

adapter.notifyDataSetChanged(); this method let list know the data has changed and update the diaplay