Description
Homework 1 (100 Points)
In this assignment you will build your second Android application. You will get familiar
with common Android components and how to interact with them. You will build a
single activity Blood Alcohol Content (BAC) Level Calculator application.
Figure 1, Application User Interface
Part 1 (30 Points): Building the Interface
The interface should be created to match the user interface (UI) presented in Figure 1.
You will be using layout files, strings.xml, and drawable files to create the user
interface. The layout XML file can be modified through the raw xml, or through the GUI
tools provided within Android Studio. To build the UI, please follow the following tasks:
1. Your application should have an application launcher icon, please select your launcher
icon to represent your app.
2. The string values used for the text labels, button labels and hints should be read
from the strings.xml file and should not be hardwired in the layout file.
3. Use an EditText component for the user to enter his/her weight in pounds. The
EditText component should be setup to limit the weight value to only positive
numbers. When the application starts the weight value EditText should be empty, and
should display the hint message “Enter Weight” as indicated in Figure 1.
4. Use a Switch widget to allow a user to set his/her gender as either Male or Female.
5. Create a Save button to save the weight and gender; you just need to save them in a
public variables. Whenever these are entered, all calculations going forward should
use the new weight and gender. Note that the text for the button should be retrieved
from the string.xml file.
6. Use a RadioGroup containing RadioButtons to enable the user to pick from the drink
size options of 1 ounce (a shot), 5 ounces (a glass), or 12 ounces (a can or bottle).
When the application starts the 1 ounce choice should be selected.
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2:30
BAC Calculator
Weight (lbs)
Drink Size
Alcohol %
Your Status:
Add Drink
Gender
1 oz 5 oz 12 oz
12%
Reset
Save
Be careful…
BAC Level: 0.04
Current Alcohol %
Indicator
Alcohol %
(Slider)
RadioGroup &
RadioButton
Gender
Toggle Switch
BAC Level
Accumulated BAC
(Progress Bar)
App Name &
App Icon
Weight
(TextView & EditText)
Save Weight
Button
Labels
(TextView)
Add Drink & Reset
Buttons
Status Label
(TextView)
hi
Enter weight
7. Use the SeekBar to enable the user to pick a custom percentage of alcohol per
volume for the selected drink. The maximum alcohol percentage value should be set
to 25%, and the slider should move in increments of 5%. When the application starts
the percentage value should be set to 5%. On the right of the SeekBar use a
TextView to display the current progress of the SeekBar, which represents the current
alcohol percentage.
8. Create an Add Drink button and a Reset button; note that the text for the buttons
should be retrieved from the string.xml file.
9. Use TextView components for creating the “BAC Level“ and “Your Status” labels.
When the application starts the “BAC Level” should be set to “0.00” and the “Your
Status” should be set to “You’re safe.”
10. Use a ProgressBar to indicate the BAC level after each drink. The maximum
progress should be set when the BAC reaches .25 or higher. When the application
starts, the ProgressBar should be set to 0.
Part 2 (70 Points): Event Handlers and App Behavior (MainActivity)
In this part you will build the required logic for the BAC calculator app. The
requirements are as follows:
1. The BAC level cannot be calculated without a weight and gender value. If a user
does not enter in and save a weight value and tries to add a drink, use the
setError() method to display an error message informing the user to “Enter the
weight in lb.”
2. If the user presses the Add Drink button, you should calculate what the current BAC
level is using the currently selected weight, gender, and drink options, based on a
(a) BAC calculated after the
first drink
(b) BAC calculated after a
drink is added
(c) BAC calculated with new
weight and additional drink
Figure 2, Application Screen Shots
2:30
BAC Calculator
Weight (lbs)
Drink Size
Alcohol %
Your Status:
Add Drink
Gender
1 oz 5 oz 12 oz
4%
Reset
Save
BAC Level: 0.04
You’re safe
150
2:30
BAC Calculator
Weight (lbs)
Drink Size
Alcohol %
Your Status:
Add Drink
Gender
1 oz 5 oz 12 oz
12%
Reset
Save
Be careful…
BAC Level: 0.07
150
Over the limit!
2:30
BAC Calculator
Weight (lbs)
Drink Size
Alcohol %
Your Status:
Add Drink
Gender
1 oz 5 oz 12 oz
18%
Reset
Save
BAC Level: 0.20
165
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simplified version of the “Widmark BAC Formula:” % BAC = (A x 6.24 / (W x r)).
[Here we are ignoring the passage of time in the formula.] See Figure 2(a).
a. A = liquid ounces of alcohol consumed = ounces * alcohol percentage (i.e. 5 x .
15)
b. W = a person’s weight in pounds
c. r = a gender constant of alcohol distribution (.68 for men and .55 for women)
d. More information on calculating BAC can found here: http://www.teamdui.com/
bac-widmarks-formula/
3. Once the BAC is calculated for the current drink, it should be added to the previous
BAC level and the “BAC Level:” label should be updated to reflect the new BAC.
Similarly, the ProgressBar should be updated to reflect the BAC, and should reach the
max whenever the BAC is equal to .25 or higher.
4. Whenever the weight/gender is changed and the Save button is pressed, the
accumulated BAC level should be recalculated based on the new weight/gender.
5. When the BAC level is less than or equal to .08, the “Your Status” label should read
“You’re safe.” See Figure 2(b). When it is greater than .08 but less than .20, it should
read “Be careful…” and when .20 or greater, it reads “Over the limit!” See Figure 2(c).
6. Whenever the BAC level reaches .25, the all buttons should be disabled, except for
the Reset button. This should be the case, even if BAC was under .25 given a
previous weight/gender, but reaches .25 or greater when recalculated with a new
weight/gender. Display a Toast that says “No more drinks for you.”
7. If the user presses the Reset button, this should reset the drink size and alcohol %
parameters to their default values, and clear the saved weight and gender values.
Any disabled buttons should be enabled again, if applicable.
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