COMP3200 Anonymous Questions and Answers

This page lists the various questions and answers. To submit a question, use the anonymous questions page. You may find the keyword index and/or top-level index useful for locating past questions and answers.

We have taken the liberty of making some minor typographical corrections to some of the questions as originally put. Although most of the questions here will have been submitted anonymously, this page also serves to answer some questions of general interest to those on the course.

Question 40:

Submission reference: IN3685

Hello David, after finishing the first bit of Assignment 2 restaurant. Should we create Restaurant Selector in a different class in the same project or should we start a different one altogether?

Answer 40:

The skeleton code we have provided contains an outline RestaurantSelector class. Complete the code in that class. The links to access the code are given in the assignment brief on the first page.

Keywords: assign2

Question 39:

Submission reference: IN3684

Hi Daivd, im currently got one error in the test class, i realise its to do with my code only taking the first element of the array that is the smallest and not going with the one that is the actual smallest. Im not sure where to go next though. Thanks

code deleted

Answer 39:

I think you have to recognise that your choice of a for-each loop means that you intend to examine every restaurant in the list. However, you are subverting that by returning from inside the body of the loop. You should not use a return statement inside a for-each loop. You can only be sure that you have found the right restaurant once the loop has fully completed. So, you need to find a way to remember that you have found a possibility but that you want to keep looking in case of something better later on in the list.

Keywords: assign2 , method-findBestPrice

Question 38:

Submission reference: IN3683

Hello, David I'm having issues with my error keeps coming up and I don't know why could you help me with it please?

code deleted

Answer 38:

You have only sent the code. What are the errors that you are having problems with? I have noticed that this code is not correct:

public int getNumberOfRestaurants() // getter method for the
NumberofRestaurants{

I would delete the comment - because it is not useful - and reformat your code like this:

public int getNumberOfRestaurants() {

Keywords: assign2

Question 37:

Submission reference: IN3682

hi there , so i wanted to ask if you can give an sample or past exam on how the limited timed assessment would look like. Since i want to start practicing for the real one that will happen on 2nd December.

Answer 37:

We will release a 'mock' in time to practice before the real thing.

Question 36:

Submission reference: IN3681

The restaurant test code that was uploaded on moodle has two errors and won't let me compile to test my restaurant class. How do i fix this? These are the lines of code on the test class that are showing up as errors, in specific ".setFoodType" and ".setAveragePrice" :

@Test
    public void testSetFoodType()
    {
	String updatedFoodType = "Italian " + rand.nextInt(10);
	aRestaurant.setFoodType(updatedFoodType);
	assertEquals(updatedFoodType, aRestaurant.getFoodType(),
		"The correct food type was not set.");
    }

and 

@Test
    public void testSetAveragePrice()
    {
	int updatedPrice = averagePrice + 1 + rand.nextInt(20);
	aRestaurant.setAveragePrice(updatedPrice);
	assertEquals(updatedPrice, aRestaurant.getAveragePrice(),
		"The correct average price was not set.");
    }

Answer 36:

What are the errors? It is your code that is likely wrong in some way. Check that you have the correct spelling of the required method names for the Restaurant class.

Keywords: assign2

Question 35:

Submission reference: IN3680

Here is my code for the removeType method:

code deleted

code deleted

Answer 35:

Remember that variable names should start with a lower-case letter, so avoid calling the variable Restaurant (upper-case 'R') because it causes confusion with the class name Restaurant.

You will need to use a different type of loop for this task. Take a look at how to iterate with a 'while loop' as the preferred solution.

You are comparing the food type correctly, so there is no need to find an alternative to that part. It is not inefficient.

Keywords: assign2 , method-removeType

Question 34:

Submission reference: IN3679

Were the test classes not given to us for the second assignment yet?

Answer 34:

That's correct. Not given to you yet.

Question 33:

Submission reference: IN3678

whats javas equivalent of the python keyword "pass". For example in python i can do:

if foo == bar:
   pass
else:
   do something

if (number >= input) {
   here is where i want to pass
   }
else {
   System.out.println("print something");
}

Answer 33:

There isn't an equivalent keyword, but you can just leave the curly brackets empty. However, in both cases, you could simply invert the condition and dispense with the else-part:

if foo != bar:
   do something

if (number < input) {
   System.out.println("print something");
}

Question 32:

Submission reference: IN3677

How detailed should the Javadoc be in our assignments? For example do we need to write a description of "The getter for the X field" and "@return X" for every getter we write?

Answer 32:

Yes, include a sentence describing the purpose and also the @return and @param tags.

Question 31:

Submission reference: IN3676

Here is the code of my class:

code deleted

Answer 31:

Because you have used = which is assignment rather than == which is the test for equality.

Question 30:

Submission reference: IN3675

Good afternoon, I'm completing exercise 5.10 in the week 13 exercises and I'm confused about what is required of me. I've written:

Book bookName;
library.add(bookName);

Student studentName;
comp3200.add(studentName);

MusicTrack songName;
track.add(songName);

Answer 30:

Sorry if the question is not clear. What it wants you to do is write the code that creates each ArrayList object and assigns that object to the field names you defined in the previous exercises. Hopefully, that is clearer.

Keywords: ex-5-10

Question 29:

Submission reference: IN3674

Hi, quick question using IntelliJ for the exercises. Some of the questions say we should look at the inspector, but this only applies to BlueJ. Can we still do this somehow in IntelliJ? Should we quickly add our own method that prints all the info to the console? Should we learn how to use the debugger? Or should we just use BlueJ? How do you suggest we approach this? Thanks

Answer 29:

You can't do it in IntelliJ. If you want to stick with IntelliJ (which is fine) I suggest that you add a method to print the current state so that you can answer the questions that relate to checking the object state.

Question 28:

Submission reference: IN3673

Write a method called spend that takes one int parameter.
The parameter value must be subtracted from the amount field only if the
parameter's value is not larger than the value of amount. You may assume
that the parameter will never be negative.
If the new amount in the money box is now smaller than leastMoney then this
method must also update leastMoney.

Answer 28:

If you come to the drop-in at 3pm in Marlowe PC2 this afternoon then we can give you directed help with that.

Keywords: assign1

Question 27:

Submission reference: IN3672

Good day. I am having issues with the JAR file we are meant to make to submit the assignment 1. Whenever I create it and save it unto my laptop and I try to open it, it never opens. I save it as a JAR file but when I click on it, it doesn't open, please is there any reason for this sir?

Answer 27:

You cannot open a JAR file on the desktop, but if you use BlueJ's Project/Open ZIP/JAR menu you can check that the files are in it.

Keywords: jar-file

Question 26:

Submission reference: IN3671

For the second method addMoney am I supposed to write an if method as well? because I have written the code as a ++ and I didn't come up as an error so I'm not sure if I need to write an if

Answer 26:

The assignment says, 'The parameter value must be added to the amount field, but only if the parameter's value is greater than zero.' So, there will need to be an if-statement. Be careful about the way you increase the amount field because using ++ only adds 1 to a variable and you want the method to add whatever value is in the parameter into amount. The parameter's value will not necessarily be 1. Use the object inspector to check that the field is correct after the call.

Keywords: assign1 , method-addMoney

Question 25:

Submission reference: IN3670

I am unsure what is wrong with my code. This is the only error I have left to fix but I cannot see what is wrong. It says that the error is to do with my spend but I included my whole code

code deleted

Answer 25:

Thank you for including your code and the error message, which helps a lot.

If you have 50 pounds in the money box, should it be possible to spend 50 pounds? If so, does your code allow that?

Keywords: assign1 , method-spend

Question 24:

Submission reference: IN3669

For the assignment, when it says write a method addMoney that takes one int parameter, what is supposed to be in the parameter is it the name of the field or you can name it anything?

Answer 24:

You can call the parameter whatever you like, but I recommend not calling it 'amount' to avoid a name clash with the amount field. Give it a name that relates to the fact that it is an amount of money being put in the money box.

Keywords: assign1 , method-addMoney

Question 23:

Submission reference: IN3668

Can you reply to emails or this page on the weekend? Can we ask for help on the assignment or we have to do it all ourselves? Do we have to write descriptive javadoc comments in bluej as well?

Answer 23:

Yes to all three questions :)

Question 22:

Submission reference: IN3667

Just wanted to check whether my constructor is correct.

code deleted

Answer 22:

You have the parameters correct, but the body of the constructor is not using the parameter values to initialise the fields. The name parameter must be used to initialise the name field and the amount parameter must be used to initialise the money fields.

Also, you have made lecturers a local variable rather than a field.

Keywords: assign1

Question 21:

Submission reference: IN3666

What am I doing wrong in this line of code? It keeps saying I'm missing a return statement with the last squiggled bracket underlining red but I cant quite tell what I have done wrong:

public boolean method(parameter)
    {
	if (condition 1) {
	    return true;
	}
	else {
	    if (condition 2) {
	    return false;
	    }
	}
    }

Answer 21:

This is exactly like one of the examples we gave in Tuesday's lecture on understanding error messages. The compiler needs to know what value to return if both condition 1 and condition 2 are false. There is no else-part in the second if-statement, so the compiler is flagging that up as an error. In your two conditions you have actually covered all the possible values of the parameter, but the compiler cannot work that out.

In fact, if you think about the way you have written your logic, you don't need both of the if-tests. So, the solution in your case is to rewrite the method to use just one if-else statement.