In this exercise you will be introduced to the mobile operating
system
Android through the
Android Studio IDE.
Preferably, you will install and use Android Studio on your own
machine, but bear in mind that it is a large system and the recommended
minimum system requirements are:
- CPU class: Intel Core i3 1.8 GHz
- RAM memory: 8 GB
If you feel your machine is not up to the task, you can install Android
Studio on your personal UMD disk space and run it on the development
machines in Heller Hall 314.
In this lab you will create an app with opening screens for an Android
version of your problem solving framework from earlier assignments.
The requirements for the app are that it:
- Provides an opening screen that:
- Introduces the problem solver, and
- Allows the user to choose the farmer, wolf, goat and cabbage
(FWGC) or 8-puzzle problem
- Depending on the user's choice, navigates to new screens that:
- Describe the FWGC or 8-puzzle problem, showing the
introduction to the problem as well as the start and end
states, and
-
Allow navigation back to the opening screen
- Displays pleasing styles
Example screens are shown in the menu at left.
Implementing the screens for actually solving the problems is the
subject of the last assignment.
As part of this lab, you should complete an Android tutorial (see menu).
This section shows example screens for this app. You need not reproduce them
exactly; in fact, you are encouraged to improve on them.
The opening screen introduces the problem solver and presents a choice.
Clicking on either button brings up a description screen for the chosen
problem.
Note:
- String output is acceptable for state display
- The "Up" (upward navigation) button
in the app bar returns the user to
the opening screen
- The "Begin FWGC Problem" button need not be responsive at
this time
The same considerations apply for the 8 puzzle description screen.
Note that the FWGC and 8 puzzle screens have different color styles.
The Android developer site has a valuable
tutorial:
Building Your First App. Be sure to study and follow
its entirety.
Note that the tutorial describes how to run the app both by running an
emulator and by connecting it to a physical Android device.
When working correctly, this app:
- Opens with a screen containing a text
input field and a SEND button
- After typing a message into the text
field, the user clicks the button and the message is displayed in a
second screen
Don't worry if the details in the tutorial do not correspond exactly to
your experience (due to your version of Android Studio being newer than
that assumed by the tutorial) — the objective of the tutorial is to
familiarize yourself with what you need to know to accomplish this lab.
- Name your project "Problem Solver"
- So that you can use Java 8 (streams and lambdas), choose a
minimum API level of 24
- You can lay out your screens using the drag-and-drop editor
for ConstraintLayouts as described in the
tutorial. However, if you prefer:
- You can lay out your screens by directly writing the XML code
- You can use layout containers such
as LinearLayout and RelativeLayout
- You can lay out your screens programmatically
(i.e. using Java code) as you did for your JavaFX problem
solver. This requires that you use the Android API.
- Make sure that all your strings, colors, and styles are
defined as resources in your project. These are found
in app/res/values as shown below.
See the menu at left for examples.
Make sure that all
strings
displayed in your screens are defined
in your
strings.xml file. For example:
When you have
strings.xml open, you can click
, which displays your string names
(keys) and their values.
With a key selected, you can click
, which allows you to enter long strings
(including
\n characters for preformatting) on multiple lines.
Make sure that all
colors
used in your screens are defined
in your
colors.xml file. For example:
defines a test color that is black. Once a color is
defined, a small
color swatch (in this case
)
will appear in the left margin opposite the
definition.
Clicking on the color swatch will produce a color
editor like that shown below on the left.
After using the editor's controls you might produce a color like that
on the right.
Make sure that all
styles used in your screens are defined in
your
styles.xml file. For example, the
MediumMono style
below could be used to display string representations of problem
states. Note:
- As you type in the body of a style item, Android Studio will
suggest values suitable for the item
- In the example below, @color/testColor refers to the color defined
in colors.xml
See the procedure for submitting Android projects on the menu to the
left.
Your project will be downloaded and run by the lab instructor.
