Realm: Create reactive mobile apps in a fraction of the time
The key class in Android menu support is misjon.info These relationships are graphically represented in Figure 5–1. Strictly speaking, this is not a class diagram, but a structural diagram Structure of Android menu classes You can group menu items together by assigning each one a group ID, which is merely an. Does not appear on workstation touchscreens. Does not The following figure shows the relationship between the menu item master and menu item definitions. Here's a quick example of how to access an Android MenuItem in a Java with the id menuItemPinQuote like this in your Android/Java code.
Using ActionProvider and ShareActionProvider Similar to an action view, an action provider replaces an action button with a customized layout. However, unlike an action view, an action provider takes control of all the action's behaviors and an action provider can display a submenu when pressed. You can build your own action provider by extending the ActionProvider class, but Android provides some pre-built action providers such as ShareActionProvider which facilitates a "share" action by showing a list of possible apps for sharing.
You can learn about this provider in the Sharing Content with Intents guide. You can also see the ActionProvider section of the ActionBar guide for more details.
This is not based on the navigation history but rather on the relationship between screens. For example, in a mail client "Back" might take the user to a previous email but "Up" would always take the user to the list of mail in the inbox. First, specify that the home icon should be used as "Up": Compile-time Configuration To specify the "up" activity at compile-time we can set the logical parent of an activity in the AndroidManifest. If you want to navigate up from current activity to its parent, but want that parent activity to preserve its state, then also specify the launch mode for the parent activity in AndroidManifest.
The existing parent activity instance will be re-used, receiving the intent through onNewIntent. Configuring the ActionBar from a Fragment Configuring the action bar from a fragment is very similar to how it's done from an activity, with a couple small differences. By default, Android assumes that fragments don't want to contribute items to the action bar.
When a fragment actually wants to add items to the action bar, it needs to tell Android about this by calling setHasOptionsMenu true in its onCreate method: Keep in mind that any action bar items added by the fragment will be appended to any existing action bar items.
This includes action bar items added by the containing activity. You can use the orderInCategory property of your action bar items to control the ordering yourself. Adding items to the menu is very similar to how it's done in an activity.
These types may have the value null. Required fields The Required annotation can be used to tell Realm to disallow null values in a field, making it required rather than optional.
If you add it to other field types, compilation will fail. Fields with primitive types and the RealmList type are required implicitly. Fields with RealmObject type are always nullable. The field type must be either a string String or an integer byte, short, int, long, Byte, Short, Integer, and Long.
Using a string field as a primary key automatically indexes the field: These looks for an object with a given primary key, and either updates it if an object with that key already exists or creates it if the key does not exist.
When you use primary keys, reads queries will be slightly faster, but writes creating and updating objects will be a little slower. If the object is a class with a primary key, this could create a conflict—there might be an object with that primary key set already.
To avoid this, you can create an unmanaged object, set its field values, then add it to the Realm with copyToRealm or insert: Indexing properties To index a field, use the annotation Index. Like primary keys, this makes writes slightly slowerbut makes reads faster. It also makes your Realm file slightly larger, to store the index.
You can index String, byte, short, int, long, boolean and Date fields. Fields marked static and transient are always ignored, and do not need the Ignore annotation. Counters Realm offers MutableRealmInteger as a special integer type. MutableRealmInteger exposes an additional API that can more clearly express intent and generate better conflict resolution steps when using Synchronized Realms.
Traditionally, a counter would be implemented by reading a value, incrementing it and setting it myObj. This will not work well in an asynchronous situation — for example when two clients are offline — because both parties will read a value, say 10, increment it, and store the value as MutableRealmIntegers are backed by traditional integer types, so no migration is required when changing a field from byte, short, int or long to MutableRealmInteger.
UI Real Estate: App Bar, Tabs, Pages and Fragments
MutableRealmInteger is not an immutable type standard like primitive number types in Java. This means the value contained inside the MutableRealmInteger can change when a Realm is written to. For this reason MutableRealmInteger fields must be marked final.
Calling set can potentially override increment and decrement operations coming from other devices pr. In some cases you might want to change this behaviour: To support two model classes with the same simple name but in different packages.
To make it easier to work with cross platform schemas as naming conventions are different. To use a Java class name that is longer than the 57 character limit enforced by Realm.
Tabs Tabs in the action bar are often where you put titles for different pages in your app. They make it easy to explore and switch between different views or functional aspects of your app, or to browse categorized data sets. Check out the Google Play app on your phone for a quick demonstration of scrollable tabs, where tab strip indicators move smoothly from tab to tab.
Extended ActionBar Guide | CodePath Android Cliffnotes
Users can gain continuous touch feedback as they swipe between pages. At onCreatethe MainActivity will load these two components to render the sliding tabs and swipeable pages.
To use the ViewPager class, you need to import support library v4 to your project. Check a previous post on how to import the library in Android Studio.
ViewPager is most often used in conjunction with Fragment, which is a convenient way to supply and manage the lifecycle of each page. There are standard adapters implemented for using fragments with the ViewPager, which cover the most common use cases.
Menu resource | Android Developers
These are FragmentPagerAdapter and FragmentStatePagerAdapter; each of these classes have simple code showing how to build a full user interface with them. In Android, adapters are a bridge between Adapter View e.
We will revisit the concept of adapter in the week 4. We put these two files under the view folder of our app package, as they are specifically created for rendering tasks. Once the tabs are set up we create 4 new fragments; we simply use the new key word in front of the class names for each of the fragments created in the files: Each fragment inflates its own layout e. Next, in our customized ActionTabsViewPagerAdapter we set up the titles for each of the created tabs.
We show a few items below. The object ID is set up; note Android has a number of nice icons we can use and in the case below we use the search and send icons from android: You can specify that a menu item appear as an action item in the XML file by using android: Depending on space could be a tablet or phone, or could be a phone flipping between portrait and landscape the item might be in the actionbar or if there is no room it will appear in the overflow menu.
You can add menu items to the menu programmatically using onCreateOptionsMenu but in our example we simply inflate the items set up in main. When any of the options are selected by the user the onOptionsItemSelected is called with the reference to the related MenuItem. In most cases the callback justs displays toast but in the case of quit we call finish to close the app. The previous example each screen is associated with an activity that is used to render and manage the user interaction with the view.
All that changes in this lecture. We move away from activities and start to use fragments -- a fragment is now used to render and manager a particular UI view. Think of fragments as lightweight activities for now. Your application still needs activities but we don't use them to solely render views.Menu with Sub Items - Android Studio Tutorial
Most applications, and ones we will develop, include one or more activity and fragments.