Week 1: Lesson 2: Learning & Understanding XML Layout-Introduction To Java For Android Course Blog

Lesson 2: Learning and Understanding XML Layout

INTRODUCTION

In this lesson you will be introduced to the folder structure of the IDE Eclipse environment and understand the difference between Relative and Linear Layouts using XML with Java for Android applications. You will also be introduced to the process for changing, viewing and manipulating the text in various XML layouts.

Lesson Objectives

By the end of this lesson you will be able to:

Section #1: What Is XML?

1. Identify the XML language and how you may use it to develop your app
2. Determine the best way to complete design and development tasks while working within the structure of the IDE Eclipse environment

Section #2: What Can XML Layouts Do for Android?

3. Examine XML Layouts in Android Development

Section #3: Differentiating between Relative and Linear Layouts in XML

4. Discern the difference between Relative and Linear Layouts using XML with Android

Section #4: Video Demonstration

5. Demonstrate how to edit and change XML code
6. Use XML code to develop the desired layout for your app project

LEARNING SEQUENCE

Required Reading	Reading the following: What is XML? by the W3C, the Internet leaders in setting standards for the Web Android Developers Layouts by multiple authors. Read down the full page to review all topics from Layouts to Filling an adapter view with data Creating an Android UI in Java Code by multiple authors. Read down the full page to review topics from Java Code vs XML Layout Files, to the final section and summary Building Menus in Android with Java and XML by Abbas Suterwala. Read the full page from Creating Menus with XML to the conclusion
Resources	View and follow the steps to the following: 1.  Eclipse (Integrated Development Environment) 2.  Android Development Tools (ADT) 3.  Video Tutorial: XML Video Tutorial: https://www.youtube.com/watch?v=91K25FRKScA Java For Android 1: Introduction To The Eclipse/Android Development Environment
Assignments	Complete the following: Video Tutorial: Java For Android 1

INSTRUCTION

Section #1: What Is XML?

In this section you will be introduced to the XML language and understand its power to support Android development.

Read: http://www.w3.org/standards/xml/core

In this reading you will be provided a definition of XML as a language and its main purpose with programming. There is a sample of the code included with descriptions for how the language is formatted. At the conclusion of reading, you will understand the benefits of using XML language and how to write it.

Section #2: What Can XML Layouts Do for Android?

In this section you will be introduced to XML layouts and the options for using them in the development of a layout for an Android application.

Read: Describe the XML for layouts used in Android Applications using Java.

http://developer.android.com/training/basics/firstapp/building-ui.html

Section #3: Differentiating between Relative and Linear Layouts in XML

Read: Android Developers Layouts

Read: http://www.techotopia.com/index.php/Creating_an_Android_User_Interface_in_Java_Code

Read: http://www.sitepoint.com/menus-in-android/

Section #4: Lesson Project Tutorial (video) XML Video Tutorials

In this video demonstration and tutorial, you will learn what the default XML code is, how to edit it, and how changing the code will impact your project. Please pause and review the video, as necessary, to complete tasks and meet these objectives:

• Recognize default code in XML
• Create your own code for the XML
• Understand what the new code does in the XML

Complete Section #4: The video will lead you through the following steps:

1. You’ll than want to begin typing what is on screen, starting with the xml version and then continuing downwards
2. The LinearLayout is the home of how your app will be set up. ‘android:orientation’ tells the device that the application will be vertical, meaning it locks the accelerometer, you can change this to being horizontal for future apps
3. ‘android:layout_width’ and ‘android:layout_height’ both control where your app is positioned. ‘Fill_parent’ describes that the app will fill the whole screen, not leaving any space on the outside of the app
4. ‘TextView’ is the code for displaying what the text in the app shows. ‘wrap_content’ describes that the text will expand to as big as the text will be, so it leaves space for the other parts of your app
5. ‘android:textSize’ describes how big you want the text to be. For this you
6. can type out px for pixel or dp for density independent pixels which is a ratio for the pixels to the screen size of the phone. Allowing the text to scale up or down depending on if you have a big size phone
7. the ‘layout_gravity’ and ‘gravity’ refer to the position of the app. The ‘layout_gravity’ tells the text where it is located on screen, it defaults to being at the top of the app, and centering it will make it in the center of the top of the app. ‘gravity’ describes that the text will be centered in the middle of it’s home in the app, which is at the top of the screen.
8. ‘id’ describes the identification of the ‘TextView’ in the Java, allowing it to be used and changed in the Java
9. The coding in the button portion of the app is the same as the ‘TextView’, just changing the ‘Button:Text’ and the ‘Button:id’ to distinguish which is adding and which is subracting
10. You have just successfully created the layout of your app. Congratulations.

SUMMARY

Additional Information Discussed In Class

JQuery Layouts

Responsive Web Apps

HTML5

Phonegap

API's

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