Frequently Asked Questions

Note: I am putting these here because students have asked them in the past, this is not a reflection of what will be on quizzes.

Q: How do people working with complex code stay organized so that they don't forget what their variables are called or accidentally make a variable more than once? So far it's been easy to keep track of my variables, but I can imagine some code would have a ton of variables in different places.

A: There are several ways computer scientists do this, first they generally have conventions on naming variables so that they don't just call them weird random names that sound funny but don't make sense later or single letter variable names like 'd' that could stand for density, or dimensions, or whatever other relevant variables start with a 'd'. Second, computer scientists have a convention of declaring as many variables as they can at the top of the program or the block of text they are working with, so that the variables are all grouped together and easy to find if you want to try to remember what a variable is called. It also really helps to comment this section (and all the other sections) Finally, computer scientists often break up their code into smaller chunks called functions or methods, each of which has their own variables, the smaller pieces of code are good for a lot of things but it often means you don't have to remember too many variable names.

Q: What other types of variables are other than the 4 main ones?

A: There are a lot of different types of variable, you will even be making your own types in a couple of weeks. Generally there are two big categories: primitives and objects. Java has 8 primitive types: int, double, char, boolean, long, float, short, and byte. The last three hardly ever come up in modern computing but will probably use all of the other five in this class. Object types are a lot more varied, there are thousands of objects types already coded into packages in Java and you will be making more object types yourself in this class.

Q: What does the class of the code mean, specifically "public class Demo{"?

A: There are several types of code groupings in computer science (class, interface, enum, etc.) Generally we don't talk about them until 200 level classes but the specification of "class" for all of your programs in this course is telling the computer that what you are working with is a "class", a piece of code that has variables and methods (like the main method and we will write more methods in a couple weeks)

Q: What does main method mean, specifically "public static void main(String [] args){"?

A: Note - you do not have to know the answer to this question for this course for some people it is helpful to know and it really throws other people to have all this information, read if you are part of the first group:

"public" means that all other classes can see this code.

"static" means it won't change depending on the instance of the class.

"void" means it won't return anything.

"main" is the name of the method.

"(String [] args)" means it can bring in a lot of Strings as values to work with if you want.

Q: What does "System.out" in the beginning of the printIn phrase do exactly?

A: It tells the System class to access the output stream.

Q: When returning a character using the System.out.println(word.charAt(4)); method, why do we start counting at 0 rather than 1?

A: Because we started programing computers using 0s and 1s, we just continue to start at 0 when couning things too.

Q: Do spaces count in the .length function when it returns the value?

A: Yes.

Q: I don't really understand how I use subtraction to decrease the value in my sunset variable by 0.05. My answer was sunset = sunset - 0.05 but I'm not sure if that's right.

A: That looks great! Just remember the semi-colon at the end.

Q: I am having difficulty understanding how after trying to simulate your examples I continuously have an error even though they are identical to what you presented.

A: Come talk to me or one of the TAs!

Q: How can we store multiple words?

A: There are several ways to do this. For now you can either put them all in one String or just make multiple variables, later you will learn better ways to store multiple connected values.