Application
Programming
Hend Alkittawi

Leaderboard App
An App to Demo File IO, Exception
Handling, Scroll Views and Dynamic
Image Loading

ANDROID APP DEVELOPMENT
-

Roadmap
-

Gather requirements

-

Design views
-

-

Design model classes
-

-

(layout xml files - setup views ids)
(classes to represent app data)

Design controller
-

(classes to connect the views and model classes with methods
to handle user interactions and to manage the data flow and
update views)

-

Create your data files

ANDROID APP DEVELOPMENT
-

At this point we have most of the tools needed to create an
application.

-

To create an application, start by gathering requirements based on
which tasks and subtasks can be identified.

-

Important questions to ask
-

What is the main purpose of the application?

-

How will the user interact with it?

-

What technology will we use?

WRITING DATA TO A FILE
-

The Assets folder is read-only, we cannot write data to the files
in the Assets folder.

-

What if we need to modify data within a file located in the Assets
folder or create a file for both reading and writing data?
-

A work around this is to create a copy of the file from the Assets
to the AVD memory, then use the “copy file” for reading and writing
data.

-

To write data to a file, create a file in the AVD memory.

-

Once created, the file can be located in the AVD memory by
navigating to View > Tool Windows > Device Explorer then data >
user > 0 > edu.utsa.cs3443.projectName > files

SCROLL VIEWS
-

A ScrollView is a view group that allows the view hierarchy
placed within it to be scrolled.

-

A ScrollView may have only one direct child placed within it.

-

To add multiple views within the ScrollView, make the direct
child you add a view group, for example LinearLayout, and
place additional views within that LinearLayout.
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</ScrollView>

IMAGE VIEWS
-

An ImageView can display an image from the drawable folder
-

statically (hard-code)
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:src="@drawable/rowdylogo"/>

-

dynamically (xml and controller class)
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/dynamic_image" />

public void displayImage(String filename){
ImageView dynamicImage = (ImageView) findViewById(R.id.dynamic_image);
int imageResource = getResources().getIdentifier(filename, "drawable", getPackageName());
dynamicImage.setImageResource(imageResource);
}

DYNAMIC LOADING OF VIEWS
-

MainActivity can dynamically place buttons in its layout
(screen)
private void dynamicSetupButton(String player){
// create a layout object
LinearLayout rootLayout = (LinearLayout) findViewById(R.id.root_layout);
Button myButton = new Button(this);
myButton.setText(player);
myButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) { Log.i(TAG, "Clicked on " + myButton.getText()); }
});
// setup the attributes for the button
LinearLayout.LayoutParams buttonAttributes
= new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
// add the button to the layout
rootLayout.addView(myButton, buttonAttributes);
}

DO YOU HAVE ANY
QUESTIONS?

THANK
YOU!

@

hend.alkittawi@utsa.edu

By Appointment
Online