There has been nothing confusing about the course yet, but I think that sometimes the slide are a little bit too vague and are kind of unclear.
If slides appear to be confusing or unclear, I would appreciate it if you could give me the page number or the web page and tell me your problem with it. The slides for this course are a ``just in time'' production as I haven't held CS1 here at RIT before and I would like to improve them, even during the course.
well i found almost everything to be confusing in what i'm doing. maybe i am the only one, maybe not. i know that because i am a begginner and just trying to see if computer science works for me. i am very confused on the key words because i have no idea what it means. i dont understand what a program does.
When a composer creates a new piece of music, he/she will write down notes for it in a language which is widely understood among musicians. He/She can send out one of his/her sheets with notes to another musician or orchestra and they (perhaps with some preparations) will be able to play it. With some luck, performances done by different orchestras will sound reasonable close.
A Java program is not much different from this. You are writing down instructions in a language and a computer is able to execute them.
In programming languages, a keyword is a reserved word which must not be used as a name for variables, methods, classes etc. One of the keywords in Java is class. That means that you are not allowed to name one of your variables class. See also the slide about identifiers.
A general remark: If everything appears to be confusing, then start with just one point you want to clarify. Write down the question and send it to me or drop into one of my office hours. But the first step is not the recognition ``I am confused'' but ``I do not understand this point''. Even if many other points are left, start with one of them.
The one point I didn't get clearly is double and the floating numbers. Where will I use them in java programs and in labs? I saw that you can declare some values as double, int, float and so on. What are the differences between them?
The numerical types double, int, and float belong to the primitive types of Java. They try to come close to whole and real numbers in Mathematics. But unfortunately you would need infinite storage to represent values like pi. On computers you have just limited storage and all these numerical types provided by Java are a compromises considering accuracy, storage requirements, and operational speed.
Numerical types for whole integers (like int or byte) are pretty simple. You have a given range (e.g. -128 to 127 in case of byte) with wrap-around in case of overflows (see the slide about 2's complement).
Floating point numbers allow you to represent numbers with fractions and very large numbers. 1e100f, for example, cannot be represented as long (because it is too large) but fits into a float even if a float needs just 32 bits in comparison to the 64 bits occupied by long. The reason for this is the representation which consists of a sign, an exponent, and a magnitude (see the corresponding slide). On the other hand, if you add 1 to 9223372036854775803, you will get the correct result if it is computed using long. In float, however, the same computation does not deliver you the correct result due to lack of precision.