UI Non-Container Elements

Button
- Represents a push-button widget.
- Push-buttons can be pressed by the user to perform an action.
- Attributes
  - text - to put a text label in the button
  - foreground - to set the colour or image for the button foreground (the whole button)
  - background - to set the colour or image for the button background (the whole button)
ImageButton
- Displays a button with an image (instead of text).
- Seems less useful than a normal Button with a specified background, because the latter gets scaled.
RadioButton
- A radio button is a two-states button that can be either checked or unchecked.
- When the radio button is unchecked, the user can press or click it to check it.
- Knows it's own state.
- Radio buttons are normally used together in a RadioGroup. When several radio buttons live inside a radio group, checking one radio button unchecks all the others.
- Attributes
  - checked indicates that radio button is on.
ToggleButton
- Displays checked/unchecked states as a button with a "light" indicator.
- Knows it's own state.
- Attributes
  - textOn and textOff are the button texts for the on and off states.
  - checked is a Boolean that indicates that the button is on (default false).
CheckBox
- A two-state button that can be either checked or unchecked.
- Knows it's own state.
- Attributes
  - text - text that is written next to the button.
  - checked is a Boolean that indicates that the button is checked (default false).
ImageView
- Displays an arbitrary image, scaled appropriately.
- Attributes
  - src - the source of the image
  - Various attributes to control the scaling.
Example
MainActivity.java
activity_main.xml
strings.xml
colors.xml
dimens.xml
happy.png, sad.png, death.png, no_death.png
TextView
- Displays text.
- Attributes
  - text - text that is displayed
  - textSize - size of text. Express in sp
  - textColor - color of the text
  - textStyle - style (bold, italic, bolditalic) for the text
  - typeface - typeface (normal, sans, serif, monospace) for the text
  - lines - the number of text lines in the view
  - clickable - to make the text clickable - by default text is not clickable.
EditText
- Editable text.
- Attributes
  - See TextView
  - hint - hint text to display when field is empty
  - inputType - indicates the type of input (text, email address, number, etc.) to help the keyboard configure itself.
  - singleLine - constrains the text to be a single scrolling line
RatingBar
- Shows a rating in stars.
- Attributes
  - isIndicator - whether this rating bar is an indicator (and non-changeable by the user).
  - numStars - number of stars in the rating
  - rating - the default number of stars to color
ProgressBar
- Visual indicator of progress in some operation.
- Can be determinate (bar) or indeterminate (cycle).
- User code is responsible for updating the bar, using a thread, or an anonymous inner class that implements Runnable, or something like that.
- Attributes
  - max - maximal value for the bar
  - progress - how mauch of the maximal value is showing
  - indeterminate - indeterminate mode
  - indeterminateBehavior - how an indeterminate progress bar behaves when empty
Example
MainActivity.java
activity_main.xml
strings.xml
dimens.xml
happy.png
WebView
- Displays web pages.
- To access web pages off the internet, you must add INTERNET permissions to the manifest
```
    <uses-permission android:name="android.permission.INTERNET" />
```
- A webview is not a browser - it simply displays HTML. If you want to browse as part of your app, start the browser application from your app.
```
    Intent browser,
    browser  = new Intent(Intent.ACTION_VIEW,Uri.parse("http://www.example.com"));
    startActivity(browser);
```
Example
MainActivity.java
activity_main.xml
strings.xml
AndroidManifest.xml
DatePicker and TimePicker
- Widgets for selecting a date and time.
- A date can be selected by spinners or a calendar.
- Attributes for DatePicker
  - spinnersShown - whether the spinners are shown.
  - calendarViewShown - whether the CalendarView is shown.
  - startYear - the first year available
  - endYear - the last year available
- A time can be selected by hour and minute spinners, and an AM/PM button.
- (Only) spinners call back to onDateChanged and onTimeChanged when a change is made.
Example
MainActivity.java
activity_main.xml
strings.xml
dimens.xml