Styles, Dialog Boxes, and Menus

1. Styles, Dialog Boxes, and Menus

2. Styles

3. Styles • Allow creation of a common format • placed in res/values/styles.xml • file name is incidental • Can be applied to multiple widgets, layouts, etc. • When applied to layout, contained widgets are not affected • If applied to different kinds of widgets, attributes that do not apply are simply ignored • One style can inherit another • attributes can be overridden • Can be used to set a theme at the application or activity level

4. Example In styles.xml: <?xml version="1.0" encoding="utf-8"?> <resources> <style name=“myStyle"> <item name="android:layout_width">wrap_content</item> <item name="android:layout_height">wrap_content</item> <item name="android:textColorHint">#FF0000</item> </style> </resources> In Activity’s corresponding .xml file: <TextView style="@style/myStyle" android:text="I am using a style template" android:id="@+id/tvStyling " />

5. Example of Inheritance Added to styles.xml: <style name="myInheritingStyle" parent="myStyle"> <item name="android:textColorHint">#0000FF</item> <item name="android:layout_marginTop">20dp</item> </style> In Activity’s corresponding .xml file: <TextView style="@style/myInheritingStyle" android:text="I am using an inheriting style template" android:id="@+id/tvInheriting " />

6. Example of a theme In styles.xml: <style name="myCustomTheme" parent="android:Theme.Light"> <item name="android:colorBackground">#0F0F0F</item> </style> In Manifest file (as an attribute of either the Activity or Application): android:theme="myCustomTheme"

7. Dialog Boxes

8. Dialog boxes • Presents information to the screen • error message • confirmation of a process • other • Overlays another Activity • usually translucent and modal

9. Dialog Boxes • Can be created in XML or programmatically • if created in XML: • use an Activity with the Dialog theme • onPause and onResume of parent fired off • advantage: can be as robust as needed • disadvantage: relatively unwieldy to pass information back from Dialog • if created programmatically • use AlertDialog class • no focus events fired off • advantage: low overhead and access to all class entities • disadvantage: interface is limited

10. Creating a DialogBox via xml

11. Creating DialogBox via xml • Create an Activity with DialogBox theme • In Manifest file: <activity android:name=".Dialog" android:label="Data Entry Error" android:theme="@android:style/Theme.Dialog"> </activity>

12. Creating DialogBox via xml • Component is technically an Activity, and all requirements remain the same • Manifest file entry, .xml file, and .java file • launched via the startActivity() method in parent Activity • intent must be created • Dialog Activity presented modally ‘in front’ of parent activity • Using an Activity with the Dialog theme allows for added functionality

13. Creating DialogBox via xml • openXMLDialog below is an example of a method within the main Activity public void openXMLDialog () { Intent i = new Intent(this, XMLDialog.class); startActivity(i); }

14. Creating a DialogBox programmatically

15. Creating DialogBox programmatically • Component is created within the current Activity • No Manifest file entry, .xml file, or .java file • launched via the show() method in AlertDialog class (from a method in the parent Activity) • Dialog Activity presented modally ‘in front’ of parent activity • setCancelable method determines if user can cancel the Dialog via the back button on the device • Minimal effort, minimal functionality

16. Creating DialogBox programmatically • Can use one, two, or three buttons • all buttons automatically dismiss the dialog after corresponding code is executed • buttons appear right to left in following order • positive • neutral • negative • No difference between the three • If none are chosen, program will be stuck with the modal dialog box • no build errors

17. Creating DialogBox programmatically public void inputError() { AlertDialog.Builder builder = new AlertDialog.Builder(this); builder.setCancelable(false); builder.setTitle("Data entry error"); builder.setMessage("Please enter a positive number in the number field"); builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() { public void onClick(DialogInterface dialog, int which) { //Functionality goes here } }); ((EditText)findViewById(R.id.etNumField)).requestFocus(); AlertDialog alert = builder.create(); alert.show(); }

18. Menus

19. Menus • Can be created in xml or programmatically • If created in .xml, placed in res\menu\ folder • Menu displayed by means of menu key on phone • Must override the following methods in Activity • onCreateOptionsMenu • creates the menu • ‘inflates’ xml code or programmatically creates menu • onOptionsItemSelected • provide the functionality to the menu

20. Creating a menu via xml

21. Creating a menu using xml • This xml file would reside in the res\menu folder <menu xmlns:android="http://schemas.android.com/apk/res/android"> <item android:id="@+id/mi1" android:title="First" android:orderInCategory="1“ android:showAsAction="never" /> <item android:id="@+id/mi2" android:title="Second" android:orderInCategory="2“ android:showAsAction="never" /> </menu>

22. Creating a menu using xml • onCreateOptionsMenu() overridden in the corresponding Activity • called only once – first time menu is displayed • onPrepareOptionsMenu is called every time menu is displayed • here ‘choices’ reflects the name of the menu xml file • a return value of true allows the menu to be shown @Override public booleanonCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.choices, menu); return true; }

23. onCreateOptionsMenu • return value • true • menu can displayed • false • menu cannot display • Scenario • When Activity is displayed, may want the Menu available under certain conditions and not otherwise if (condition met) return true; else return false;

24. Creating a menu using xml • onOptionsItemSelected() overridden in the corresponding Activity • Here ‘miX’ reflects the name of the menu item in the xml file @Override public booleanonOptionsItemSelected(MenuItem item) { switch(item.getItemId()) { case (R.id.mi1): //Functionality here case (R.id.mi2): //Functionality here } return true; }

25. onOptionsMenuItem • return value • true • consume menu processing here • will not call super class’ onOptionsMenuItem • false • will call super class’ onOptionsMenuItem • Scenario • May have one activity that implements the menu, and others that subclass it • if subclass handles subset of cases, handle those and return false in any case that is not handled

26. Creating a menu programmatically

27. Creating a menu programmatically • onCreateOptionsMenu() overridden in the corresponding Activity • Each menu item added via the ‘add’ method in the Menu class • parameters are: • group id, item id, order, title • group id useful if actions need to be taken on a group of items • removeGroup(), setGroupVisible(), etc. • item id is the unique id (value returned by getItemId()) • items will appear in numerical order by order parameter public booleanonCreateOptionsMenu(Menu menu) { menu.add(Menu.NONE, 1, 1, "First"); menu.add(Menu.NONE, 2, 2, "Second"); return true; }

28. Creating a menu programmatically • onOptionsItemSelected() overridden in the corresponding Activity • getItemId() matches those set in onCreateOptionsMenu() @Override public booleanonOptionsItemSelected(MenuItem item) { switch(item.getItemId()) { case 1: //Functionality here case 2: //Functionality here } return true; }