Mobile Computing Lecture#11 Adapters and Dialogs

Lecture Contents  Adapter  SimpleCursorAdapter  ArrayAdapter  Dialog  Dialog Class  Dialog-themed Activity  Toasts 2

Adapters Adapters are bridging classes that bind data to Views (such as List Views) used in the user interface. The adapter is responsible for 1. Creating the child Views used to represent each item within the parent View (say a ListView) 2. Providing access to the underlying data (say an ArrayList) 3

Simple Cursor Adapter  An easy adapter to map columns from a cursor to TextViews or ImageViews  You can specify which columns you want, which views you want to display the columns, and the XML file that defines the appearance of these views. 4

Simple Cursor Adapte Example 5

6

ArrayAdapter  The Array Adapter uses generics to bind an Adapter View to an array of objects of the specified class  By default the Array Adapter uses the toString() value of each object in the array to create and populate Text Views  Alternative constructors enable you to use more complex layouts  You can even extend the class to use alternatives to Text Views (to display data) 7

ArrayAdapter Example Steps Involved:::: 1. Layout Definitions 2. Adapter Class 3. Activity to show elements 8

ArrayAdapter Example (Adapter Class) 9

10 ArrayAdapter Example (Main Class)

ArrayAdapter Example (row.xml) 11

ArrayAdapter Example (main.xml) 12

ArrayAdapter Example (Output) 13

ArrayAdapter Complex Example Steps Involved:::: 1. Layout Definitions 2. View Data Class 3. Adapter Class 4. Activity to show elements 14

Layouts 15

Data Class 16

Student Adapter 17

Main 18

Dialogs  Dialog boxes are a common UI metaphor in desktop, web, and mobile applications  They’re used to help users answer questions, make selections, and confirm actions, and to display warning or error messages  Dialog boxes in Android are partially transparent, floating Activities that appear upon activities that launch them 19

Implementing Dialogs There are three ways to implement a dialog in Android: 1. Using Dialog class 2. Dialog-themed Activity 3. Toasts 20

Using Dialog Class or Its Extensions  Android includes a number of specialist classes that extend Dialog  Each is designed to provide specific dialog-box functionality  Dialog-class-based screen is constructed entirely within its calling Activity, so it doesn’t need to be registered in the manifest  Dialog’s life cycle is controlled entirely by the calling Activity 21

Dialog Creation Dialog d = new Dialog(MyActivity.this); // Have the new window tint and blur the window it obscures. Window window = d.getWindow(); int flag = WindowManager.LayoutParams.FLAG_BLUR_BEHIND; window.setFlags(flag, flag); d.setTitle("Dialog Title"); // Set title d.setContentView(R.layout.dialog_view); // Inflate layout // Find the TextView used in the layout and set its text value TextView text = (TextView)d.findViewById(R.id.dialog); text.setText("This is the text in my dialog"); d.show(); 22

Dialog output 23

Dialog with Buttons final Context context = Main.this; String title = "It is Pitch Black"; String message = "You are likely to be eaten by a ghost"; String button1String = "Go Back"; String button2String = "Move Forward"; AlertDialog.Builder ad = new AlertDialog.Builder(context); ad.setTitle(title); d.setMessage(message); ad.setPositiveButton(button1String, new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int arg1) { //Do something positive } }); ad.setNegativeButton(button2String, new DialogInterface.OnClickListener(){ public void onClick(DialogInterface dialog, int arg1) { //Do something negative } }); ad.show(); 24

Dialog with Buttons 25

Toast  Android allows us to display a message without any button like 'OK' or 'Cancel'  Its helps us to display a short message in short time  Call Toast.makeText()  Provide necessary arguments (Context, Message, Duration)  Call show() message to display toast 26

Syntax/Example 27  Toast Syntax Toast.makeText(Context, Message, Duration).show() ToastExample::::: Toast.makeText(MyActivity.this, “You have been assigned a project”, Toast.LENGTH_LONG).show();

Custom Toast Toast toast = new Toast(MyActivity.this); TextView toastView = new TextView(MyActivity.this); toastView.setText("Here goes your message"); toastView.setBackgroundColor(Color.WHITE); toastView.setTextColor(Color.RED); toastView.setPadding(10,10,10,10); toast.setView(toastView); toast.setDuration(Toast.LENGTH_LONG); toast.setGravity(Gravity.CENTER, 0, 0); toast.show(); 28

Regular/Custom Toast 29