ANDROID 4.4 APP DEVELOPMENT ESSENTIALS BOOK PDF
Development Essentials. Page 2. ii. Android App Development Essentials – First Edition. ISBN The content of this book is provided for informational purposes only. Neither the publisher nor Save as PDF. You are currently reading the Eclipse - Android Edition of this book. Purchase the fully updated Android Studio / Android 9 / Jetpack. The goal of this free book is to teach the skills necessary to develop Android based applications using the Eclipse Integrated Development Environment (IDE) .
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android 44 app development essentials is available in our book collection an online access to it is Android App Development Essentials: Neil Smyth. Download [PDF] Android 4 4 App Development Essentials Free. Android App Development Essentials The goal of this book is to teach the skills necessary to develop Android based applications using. Android App Development Essentials Neil Smyth This book is for sale at This version was published on This is a Leanpub book. Leanpub.
Check the online developer documentation for your device to find out if emulator definitions are available for download and installation into the ADT environment. When launched, an AVD will appear as a window containing an emulated Android device environment.
New AVDs are created and managed using the Android Virtual Device Manager, which may be used either in command-line mode or with a more user-friendly graphical user interface. Alternatively, the tool may be launched from the command-line using the following command: Within the dialog, perform the following steps to create a first generation Nexus 7 compatible emulator: Enter a descriptive name for example Nexus7 into the name field.
Note that spaces and other special characters are not permitted in the name. Set the Device menu to Nexus 7 x Set the Target menu to Android 4. Keep in mind however, that it may be necessary to reduce the RAM value below M on Windows systems with less available memory. If the host computer contains a web cam the Front Camera: Alternatively, an emulated camera may be selected. If camera functionality is not required by the application, simply leave this set to None.
Whether or not you enable the Hardware Keyboard and Display skin with hardware controls options is optional. When the hardware keyboard option is selected, it will be possible to use the physical. As such, the Android software keyboard will not appear within the emulator. The skin with hardware controls option controls whether or not buttons appear as part of the emulator to simulate the hardware buttons present on the sides of the physical Android device.
Note that it may also be possible to speed the performance of the emulator by enabling the Use Host GPU option. In the event that the emulator crashes during startup when this option is selected, edit the virtual device properties and disable this option.
Figure 3 3 illustrates the dialog with the appropriate settings implemented for a Nexus 7 emulator. Once the configuration settings are complete, click on the OK button. The emulator will appear in a new window and, after a short period of time, the android logo will appear in the center of the screen. The first time the emulator is run, it can take up to 10 minutes for the emulator to fully load and start.
On subsequent invocations, this will typically reduce to a few minutes.
In the event that the startup time on your system is considerable, do not hesitate to leave the emulator running. The ADT system will detect that it is already running.
Creating an Android Virtual Device AVD 22 and attach to it when applications are launched, thereby saving considerable amounts of startup time. Once fully loaded, the emulator will display either the standard Android lock screen. This is achieved using the android tool in conjunction with some command-line options.
Once initiated, the tool will prompt for additional information before creating the new AVD. Assuming that the system has been configured such that the Android SDK tools directory is included in the PATH environment variable, a list of available targets for the new AVD may be obtained by issuing the following command in a terminal or command window: Available Android targets: Android 4.
Platform API level: Once a new AVD has been created from the command line, it may not show up in the Android Device Manager tool until the Refresh button is clicked. In addition to the creation of new AVDs, a number of other tasks may be performed from the command line.
For example, a list of currently available AVDs may be obtained using the list avd command line arguments: KindleFireHD7 Path: Nexus7 Path: Nexus7Google Path: These settings may be changed directly within the configuration file and will be adopted by the AVD when it is next invoked.
Note that a change to the image. AVDs are created and managed using the Android AVD Manager tool which may be used either as a command line tool or using a graphical user interface.
When creating an AVD to simulate a specific Android device model it is important that the virtual device be configured with a hardware specification that matches that of the physical device. Now that we have created and configured an AVD, the next step is to create a simple application and run it within the AVD.
Creating an Example Android Application The preceding chapters of this book have covered the steps necessary to configure an environment suitable for the development of Android applications. Before moving on to slightly more advanced topics, now is a good time to validate that all of the required development packages are installed and functioning correctly.
Android Studio 2.3 Development Essentials - Android 7 Edition.pdf
The best way to achieve this goal is to create a simple Android application, compile it and then run it within an Android Virtual Device AVD emulator. Begin, therefore, by launching Eclipse and accepting the default path to your workspace in the Workspace Launcher dialog as illustrated in Figure 4 1 or choose another location if the default is unsuitable. Note that if you do not wish to be prompted for the location of the workspace each time Eclipse loads, simply select the Use this as the default and do not ask again option before clicking on OK.
Creating an Example Android Application 26 Figure 4 1 Once the workspace has been selected, the main Eclipse workbench window will appear ready for a new project to be created.
The Package Name is used to uniquely identify the application within the Android application ecosystem. It should be based on the reversed URL of your domain name followed by the name of the application.
For example, if your domain is and the application has been named AndroidTest, then the package name might be specified as:. Creating an Example Android Application 27 com. Once these settings have been configured, the dialog should match that shown in Figure 4 2: Figure 4 2.
Within this screen, a number of different configuration options are provided. Make sure that the Create Activity and Create customer launcher icon options are selected. The former setting will ensure that the project is preconfigured with a template activity that will make the task of creating an example application easier. An activity is a single task that can be performed by the user within the context of an application and is typically analogous to a single user interface screen within an application.
In asking for Eclipse to create an activity for us, therefore, the project will be primed with both a window onto which a user interface may be displayed and the code to ensure that the window appears when the application runs.
The custom launcher selection, on the other hand, will provide the option to specify the icon that will represent the application on the device screen. Before the application can be submitted to the Google Play app store for sale it will need to have an icon associated with it.
This icon is displayed on the screen of the Android device and is touched by the user to launch the application. The launch icon can take the form of a set of PNG image files, clipart or even text. Options are also provided on this screen to configure the background color of the launcher and to change the shape surrounding the icon. When assigning image files for the launcher icon, images for a variety of screen resolutions and densities may be specified.
If only a single image size is provided, the Android system will scale the. Creating an Example Android Application 30 image for different screens, potentially leading to some image quality degradation. For the purposes of this example, however, it is adequate to use the default icon images: A range of different activity types is available when developing Android applications. On the final screen Figure 4 6 name the activity AndroidTestActivity.
Finally, since this is a very simple, single screen activity, there is no need to select a navigation type, so leave this menu set to None. Finally, click on Finish to initiate the project creation process.
If the Welcome! The newly created project and references to associated files are listed in the Package Explorer located in a panel on the left hand side of the main Eclipse window. Clicking on the right facing arrow next to the AndroidTest project name will unfold the project and list the various files and sub-folders contained therein.
This essentially mirrors the directory hierarchy and files located in the project s workspace folder on the local file system of the development computer:. Creating an Example Android Application 33 Figure 4 7 The example project created for us when we selected the option to create an activity consists of a user interface containing a label that will read Hello World when the application is executed.
If, at this point, more than one AVD emulator has been configured on the system, a window will appear providing the option to select which AVD environment the application will run in.
Introduction to Android 4.4 App Development Essentials
If multiple AVDs are listed, select the Nexus7 emulator created in the earlier chapter. In the event that only one AVD is available, Eclipse will automatically launch that virtual device. The AVD window typically appears immediately, but a delay may be encountered as the emulator starts up and loads the Android operating system. Once the operating system has loaded, the example application will run and appear within the emulator as shown in Figure 4 8: Figure 4 8 In the event that the activity does not automatically launch, check to see if the launch icon has.
Creating an Example Android Application 34 appeared on the emulator screen. If it has, simply click on it to launch the application. When the application has launched, an additional window may appear asking whether or not LogCat messages should be monitored. When an application is running, a range of diagnostic messages is output by the system.
In addition, the application developer may have included diagnostic messages into the application code. It is generally recommended, therefore, that monitoring of these messages be enabled. Assuming that the application loads into the emulator and runs as expected, we have safely verified that the Android development environment is correctly installed and configured.
It is also possible to manually stop a running application from within the Eclipse environment. The default configuration for Eclipse is to launch showing the Java perspective and for a button to be located in the top right hand corner of the main Eclipse screen Figure 4 9 that allows the DDMS perspective to be displayed.
Creating an Example Android Application 36 Figure 4 10 The left hand panel, entitled Devices, lists any devices or emulators to which the development environment is attached. Under each device is a list of processes currently running on that device or emulator instance.
Figure 4 11, for example, shows the Devices panel with the AndroidTest application running:. Creating an Example Android Application 37 Figure 4 11 To terminate the AndroidTest application, select the process from the list and click on the red Stop button located in the Devices panel toolbar.
To return to the main Java development perspective, simply click on the Java button in the Eclipse toolbar. Using the Package Explorer panel, locate this file as illustrated in Figure 4 Creating an Example Android Application 38 Figure 4 12 Once located, double click on the file to load it into the user interface builder tool which will appear in the center panel of the Eclipse main window: Figure 4 13 In the toolbar across the top of the layout editor panel is a menu that is currently set to Nexus One.
Since we are designing a layout for the screen of a Nexus 7 device, click on the menu and select the Nexus 7 x The visual representation of the device screen will subsequently change to reflect the dimensions of the Nexus 7 device. If you have created a custom AVD for another device, this may also be selected from the menu so that the design canvas matches that device.
To change the orientation between landscape and portrait simply use the drop down menu.
Creating an Example Android Application 39 immediately to the right of the device selection menu showing the icon. In the center of the panel is the graphical representation of the user interface design, now within the context of a Nexus 7 device.
As can be seen, this includes the label that displays the Hello World message. Running down the left hand side of the panel is a palette containing different categories of user interface components that may be used to construct a user interface, such as buttons, labels and text fields. It should be noted, however, that not all user interface components are obviously visible to the user.
One such category consists of layouts.
Android supports a variety of different layouts that provide different levels of control over how visual user interface components are positioned and managed on the screen.
Though it is difficult to tell from looking at the visual representation of the user interface, the current design has been created using a RelativeLayout. This can be confirmed by reviewing the information in the Outline panel that, by default, is located on the upper right hand side of the Eclipse main window and is shown in Figure 4 Figure 4 14 As we can see from the outline, the user interface consists of a RelativeLayout parent that has as a child the TextView object.
The first step in modifying the application is to delete the TextView component from the design. Begin by clicking on the TextView object within the user interface view so that it appears with a blue border around it. Once selected, press the Delete key on the keyboard.
From the Palette panel, select the Form Widgets category if it is not already selected. Click and drag the Large TextView object and drop it in the center of the user interface design green marker lines will appear to indicate the center of the display:. When developing applications, attributes and values such as text strings should be stored in the form of resources wherever possible.
Doing so enables changes to the appearance of the application to be made by modifying resource files instead of changing the application source code. This can be especially valuable when translating a user interface to a different spoken language. If all of the text in a user interface is contained in a single resource file, for example, that file can be given to a translator who will then perform the translations and return the translated file for inclusion in the application. This enables multiple languages to be targeted without the necessity for any source code changes to be made.
In this instance, we are going to create a new resource named welcomestring and assign the string Welcome to Android to it. On returning to the Resource Chooser, make sure welcomestring is selected before clicking on OK. Once changes have been made to a file within Eclipse, it is important to remember to save the changes before moving on to other tasks.
Eclipse also allows multiple files to be open for editing simultaneously. Each open file is represented by a tab along the top edge of the editing panel. To close an open file, simply click on the X next to the file name in the corresponding tab.
Clicking on this will display a dropdown list of all open files. Figure 4 16, for example, shows tabs for three currently open files together with an indication that another seven.
Java beans provide support for encapsulating the data. Member variables are troublesome in servlets; they can cause errors that are hard to debug.
A helper class is introduced to allow the application to use member variables. Inheritance is used to separate the first group into a base class that can be reused by all servlets. Chapter 4 adds features to the web application and provides code for simplifying some of the common tasks of a controller. The Log4j package is added to the web application and a logger is added to the controller.
Chapter 5 introduces required validation and data persistence are. Both are implemented using the Hibernate package. Recent Books. IT Research Library. Miscellaneous Books. Computer Languages. Computer Science. Electronic Engineering.
Linux and Unix. Microsoft and. Mobile Computing.Appcelerator, Inc. Within the Android SDK Manager, make sure that the check boxes next to the following packages are listed as Installed in the Status column:. Adapt the syntax and design of mobile web pages to target smartphone models.
Introduction to Android 4.4 App Development Essentials
Eclipse editions with which the ADT Plugin is compatible are as follows:. A helper class is introduced to allow the application to use member variables. Using the Package Explorer panel, locate this file as illustrated in Figure 4 If camera functionality is not required by the application, simply leave this set to None.
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