Allan SWC Exercises Stamp
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RHS
Allan SWC Exercises Stamp
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The problem
You are to develop a program, which can find the price for
a stamp for a letter depending on the letters weight.
The table below shows the relation between letters weight and stamp price
Letter |
Stamp price |
|||||||
0 g |
< |
weight |
<= |
50 g |
4.50 DKK |
|||
50 g |
< |
weight |
<= |
100 g |
6.50 DKK |
|||
100 g |
< |
weight |
<= |
250 g |
12.50 DKK |
|||
250 g |
< |
weight |
<= |
500 g |
21.00 DKK |
|||
500 g |
< |
weight |
<= |
1000 g |
29.00 DKK |
|||
1000 g |
< |
weight |
42.00 DKK |
The solution
Create a project "Stamp" and create a new "Java class" and give it the
name StampCalculator - uncheck the "Create Main Class" as we will create the application class later.
Declare a method in StampCalculator using the template below:
public double getPrice(int weight) {
.....
}
Construct the code so it returns the price relevant for the given weight using the table above -
you'll need a lot of nested if-else statements!
Compile it.
Testing the calculator
Now add a new file, choose "Java GUI Forms -> JFrame Form" - give it the name
StampTestForm
Place a JPanel on the form and
add a label and a text-field for entering the weight value, a label for
showing the output (the price of the stamp) and a button to activate the action.
Your form should look something like:
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Important: Add a instance variable of the StampCalculator type in the form-class (at the bottom of the file as usual) - remember to construct the object!
Now add code to the buttons action-event handler so a click will read the value from the text-field, typecast it to numerical (use Integer.parseInt()) and activates the getPrice() method in the StampCalculator object using the numerical value as argument.
The return value from this method should be put
into the output-label.
Below is an example of this:
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Adapting the StampCalculator
In your study-group discuss the following:
Change the method getPrice() into static and do the necessary changes in StampTestForm