Android Dialogs Overview

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Questions and Answers

Which method is used to detect touch events in a view?

onTouchEvent(View v, MotionEvent event)

onClick(View v)

onLongClick(View v)

onTouch(View v, MotionEvent event) (correct)

What information does the getX() method provide in MotionEvent?

The X coordinate of the touch relative to the widget. (correct)

The raw X coordinate including screen offsets.

The X coordinate of the touch regarding the entire screen.

The X coordinate of the last touch event only.

What does the getAction() method of MotionEvent return?

The number of fingers touching the screen.

The specific X, Y coordinates of the event.

The type of touch action performed. (correct)

The duration of the touch event.

What is the purpose of returning true in the onTouch method?

To confirm that the event has been consumed. Signup and view all the answers

Which of the following actions is NOT part of the possible return values of getAction()?

ACTION_CLICK Signup and view all the answers

What is the purpose of a dialog in a user interface?

To prompt users for additional information without dominating the interface. Signup and view all the answers

Which of the following is a predefined dialog type used for selecting a specific time?

TimePickerDialog Signup and view all the answers

Which method is used to set the positive button in an AlertDialog?

setPositiveButton() Signup and view all the answers

What does the method builder.setCancelable(false) accomplish in a dialog?

Prevents the dialog from being dismissed by the user. Signup and view all the answers

What type of dialog is deprecated for general use in newer APIs?

ProgressDialog Signup and view all the answers

Which method is specifically used to incorporate radio buttons into a dialog?

setSingleChoiceItems() Signup and view all the answers

In creating a custom dialog, what element can you define at will?

The layout of the dialog Signup and view all the answers

What is the correct syntax to instantiate an AlertDialog.Builder in a given class?

new AlertDialog.Builder(MainActivity.this); Signup and view all the answers

What is the primary purpose of the AlertDialog in the given code?

To provide a layout for user input Signup and view all the answers

Which class is used to create an AlertDialog Builder in the provided code?

ContextThemeWrapper Signup and view all the answers

What is the role of the OnClickListener within the AlertDialog?

To define what happens when a button is clicked Signup and view all the answers

Why can't a listener be attached directly to a screen according to the content?

Listeners are only available for specific widget types Signup and view all the answers

In the context of input mechanisms, what is unique about sensor listeners compared to other input methods?

They function independently from the application interface Signup and view all the answers

What does the 'setCancelable(false)' method call do in the AlertDialog Builder?

Disallows dismissal of the dialog when the user clicks outside it Signup and view all the answers

What happens when the 'Done' button is clicked within the dialog?

The input text is retrieved and a listener is triggered Signup and view all the answers

Which of the following methods is NOT mentioned as a way to handle input in the content provided?

Mouse clicks Signup and view all the answers

In the context of adding listeners, what does 'EditView' specifically refer to?

A widget that accepts user text input Signup and view all the answers

What is the purpose of using 'FragmentEditNameBinding' in the provided code?

To facilitate data binding for UI components Signup and view all the answers

Which of the following attributes is essential for a View to function with listeners?

android:focusableInTouchMode Signup and view all the answers

What method must be overridden to implement keyboard input handling in a View?

onKey(View v, int keyCode, KeyEvent event) Signup and view all the answers

What is a primary advantage of using DialogFragments over traditional AlertDialogs?

They are lifecycle-aware and better aligned with fragments. Signup and view all the answers

Which of the following is NOT a method that can be overridden when extending a View class?

onLayout(boolean changed, int left, int top, int right, int bottom) Signup and view all the answers

In the provided code, which purpose does the 'show' method serve when working with DialogFragments?

It triggers the dialogFragment to appear on the screen. Signup and view all the answers

What will the event.getMatch(char[] chars) method return if there is no match found?

An empty string Signup and view all the answers

What does the second parameter of 'setSingleChoiceItems' method in AlertDialog signify?

The default selected item index. Signup and view all the answers

Which key code would be used to check for a press on the camera button?

KeyEvent.KEYCODE_CAMERA Signup and view all the answers

What must you implement in a DialogFragment to manage its creation and lifecycle?

onCreateDialog(Bundle) Signup and view all the answers

To add a key listener to an ImageView, which of the following is the correct way?

iv.setOnKeyListener(new MyKeyListener()) Signup and view all the answers

What is a limitation of using AlertDialog.Builder when compared to DialogFragments?

AlertDialog lacks lifecycle awareness. Signup and view all the answers

Which of the following character codes can be used to identify the ZERO key?

KeyEvent.KEYCODE_0 Signup and view all the answers

What is one of the steps to show a DialogFragment as illustrated?

Use the show method with the FragmentManager. Signup and view all the answers

When a key event is triggered, which of the following methods is NOT directly associated with handling that event?

onUserInteraction() Signup and view all the answers

Which option is NOT a valid operation defined in the items array?

Change Walls Signup and view all the answers

What does invoking iv.setOnKeyListener(new myKeyListener()) accomplish?

Registers a key listener for keyboard input on the ImageView. Signup and view all the answers

When creating a dialog using DialogFragment, which lifecycle method is optional to implement?

onCreateView(LayoutInflater, ViewGroup, Bundle) Signup and view all the answers

What does the dismiss method do in the context of a DialogFragment?

It closes the dialog and releases any resources. Signup and view all the answers

Which of the following is true about the focus state of a View when using a key listener?

The View must be focused to receive key events. Signup and view all the answers

What does the default index (-1) in the setSingleChoiceItems method indicate?

No item is selected by default. Signup and view all the answers

Study Notes

Dialogs

A dialog is a small window that provides additional information without filling the whole screen.
It prompts users for decisions (e.g., Save, Cancel, Exit).
It displays extra information (e.g., Progress, Date/Time).

Dialog Types

AlertDialog: Standard dialog, up to three buttons (e.g., Positive, Negative, Cancel).
ProgressDialog: Displays progress (deprecated for general newer APIs).
DatePickerDialog and TimePickerDialog: Predefined dialogs for selecting dates or times.
Custom Dialogs: User-defined layouts used in dialogs.

Creating a Dialog

Use AlertDialog.Builder to create a dialog.
Up to three buttons: "positive," "negative," and "cancel".
Set positive and negative buttons, disable cancel if needed.

AlertDialog

Instead of buttons, you can use radio buttons (more than just three).
Use Builder.setSingleChoiceItems.
Provide a CharSequence array for the items (e.g., "Remove Walls," "Add Walls").

DialogFragment

Use DialogFragment instead of AlertDialog.Builder.
Implement onCreateDialog(Bundle).
Optionally implement onCreateView.
DialogFragments can be added to a frameLayout or use show method.

Why Use DialogFragments?

Lifecycle-aware.
Better alignment with fragments in modern Android.

Input (Keyboard, Touch, Controllers, and Device Sensors )

For most inputs, add a custom listener to the view class.
EditText has a keyboard listener since it accepts input.
You add a listener to a view (widgets), and then it only works for that widget.
Unless a view takes up the entire screen, there's no listener for a "screen".
The exception is the sensor, where it's for the device.

View

A View class to extend and create custom views.
Use ImageView widget and add listeners.
Note: Views need attributes to work with listeners (android:focusable="true", android:focusableInTouchMode="true", and android:clickable="true").

Keyboard Input

This is a section concerning standard keyboard input.

View.OnKeyListener

Implements View.OnKeyListener.
Override the onKey method (public boolean onKey(View v, int keyCode, KeyEvent event)).
Note: There's no char field; you get the KeyCode.

View.OnKeyListener (What key was pressed?)

Use event.getMatch(char[] chars) to check against character arrays.
Returns the character if a match is found, \0 otherwise.
Use KeyEvent.Constants (e.g., KEYCODE_0).
Example constants (e.g., KEYCODE_CAMERA, KEYCODE_DPAD_LEFT).

View.OnKeyListener (Adding a listener)

Add a listener to the view (e.g., ImageView).
iv.setOnKeyListener(new myKeyListener()).
Listener is called when the view gets focus.

View Overrides

When extending a View class you also override onKeyDown(int, KeyEvent), onKeyUp(int, KeyEvent), onTrackballEvent(MotionEvent).

Touch Input

There's an OnTouchListener.
You can also use OnClickListener and OnLongClickListener, especially for buttons.

View.OnTouchListener

Implements View.OnTouchListener.
Override onTouch(View v, MotionEvent event).
onTouch returns true if the event is handled, false otherwise.
This method has info about the touch event (MotionEvent).

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Description

Explore the various types of dialogs in Android, including AlertDialog, ProgressDialog, and custom dialogs. This quiz covers their functionalities and how to create them using builders, as well as the specifics like buttons and choice options.