Category «Android Basics»

RelativeLayout in Android

The RelativeLayout is the most powerful layout available. All children in a RelativeLayout can be positioned relative to each other or to their parent. For example : you can tell a view to be positioned to the left or right of another view. Or, you can specify that a view is aligned to the bottom …

LinearLayout in Android

A LinearLayout is a layout that arranges its children either horizontally or vertically, depending on the value of its orientation property. The LinearLayout is the easiest layout to use. A LinearLayout can also have a gravity attribute that affects its gravity. A horizontal LinearLayout Example <LinearLayout xmlns:android=“http://schemas.android.com/apk/res/android” xmlns:tools=“http://schemas.android.com/tools” android:orientation=“horizontal” android:layout_width=“match_parent” android:layout_height=“match_parent”> <ImageButton android:src=”@android:drawable/btn_star_big_on” android:layout_width=“wrap_content” android:layout_height=“wrap_content”/> …

Android Layouts

Layouts are important because they directly affect the look and feel of application. Technically, a layout is a view that arranges child views added to it. Android comes with a number of built-in layouts, ranging from LinearLayout, which is the easiest to use, to RelativeLayout, which is the most powerful. Layout Overview An important Android component, …

Android PendingIntent Class

A PendingIntent encapsulates an Intent and an action that will be carried out when its send method is invoked. Since a PendingIntent is a pending intent, the action is normally an operation that will be invoked some time in the future, most probably by the system. For example, a PendingIntent can be used to construct …

Android Notifications

A notification is a message on the status bar. Unlike a toast, a notification is persistent and will keep showing until it is closed or the device is shut down. A notification is an instance of android.app.Notification. The most convenient way to create a notification is by using a nested class called Builder, which can …

Android AlertDialog

AlertDialog is a window that provides feedback to the user. Unlike a Toast that fades by itself, however, an AlertDialog shows indefinitely until it loses focus. In addition, an AlertDialog can contain up to three buttons and a list of selectable items. A button added to an AlertDialog can be connected to a listener that gets …

Android APK File

An Android application is packaged into an apk file, which is basically a zip file and can be opened using WinZip or a similar program. All applications are signed with a private key. This process sounds hard enough, but thankfully Android Studio takes care of everything. When you run an Android application from inside Android …

Android Manifest file

Every Android application must have a manifest file called AndroidManifest.xml file that describes the application. A sample manifest <?xml version=“1.0” encoding=“utf-8”?> <manifest xmlns:android=“http://schemas.android.com/apk/res/android” package=“com.example.firstapp” > <application android:allowBackup=“true” android:icon=”@drawable/ic_launcher” android:label=”@string/app_name” android:theme=”@style/AppTheme” > <activity android:name=“com.example.firstapp.MainActivity” android:label=”@string/app_name” > <intent-filter> <action android:name=“android.intent.action.MAIN” /> <category android:name=“android.intent.category.LAUNCHER” /> </intent-filter> </activity> </application> </manifest> A manifest file is an XML document with manifest as …

Adding Swipe-to-Refresh To Your App in Android

The swipe-to-refresh user interface pattern is implemented entirely within theSwipeRefreshLayout widget, which detects the vertical swipe, displays a distinctive progress bar, and triggers callback methods in your app. You enable this behavior by adding the widget to your layout file as the parent of a ListView or GridView, and implementing the refresh behavior that gets …