Help in Java from any expert.

Question

Hi, i am new to the Java language, and am taking it in school. Unfortunately, my teacher has never taught grade 11 Java before and so he doesnt really understand what to teach us. He expects us to know a lot of things that we dont, and tries to make us do riduclous things (on tests, even!) that we have never heard of. He only teaches interesting things to his favourite students, and to the rest of us he gives a really bad explanation, which he refuses to comment on.
I have a couple of questions for you guys, since you're all probably experts here. IF you dont mind answering them, it would be great. I will ask more in the future, but for now:
1) What is an object? I really dont understand how you can have objects in java. What can they do, wht characteristics do they have?
2) What is inheritance? i understand what the word means, but how can this relate to Java? provide an example if you can, please.
3)How do threads work? If i wanted to make a a character that moves around a screen, while another character is doing the same thing, how would i make the thread do that?
Thanks for all the help.

Answer 1

First let me say that the answers that preceded this one really do have all you need to know, and they came from real experts. I'll take a stab at answering your actual questions:
Hi, i am new to the Java language, and am taking it
in school. Unfortunately, my teacher has never taught
grade 11 Java before and so he doesnt really
understand what to teach us. He expects us to know a
lot of things that we dont, and tries to make us do
riduclous things (on tests, even!) that we have never
heard of. He only teaches interesting things to his
favourite students, and to the rest of us he gives a
really bad explanation, which he refuses to comment
on.I cannot comment on your teacher, but I suspect your view is coloured by the fact that you are not one of the "favorites".
I have a couple of questions for you guys, since
you're all probably experts here. IF you dont mind
answering them, it would be great. I will ask more in
the future, but for now:We're not all "experts", but many of us are professional programmers working in the Java language at the present time. this may not always be the case in the future.
1) What is an object? I really dont understand how
you can have objects in java. What can they do, wht
characteristics do they have?An "object" is a construct in a computer language that may have both state and behaviour.
By state we mean that the object has some attributes or variables that define how it differs from other objects of the same type, or even from itself at a different time. An example of state is that the object could have a colour and an age. The colour would be permanent, but the age would tend to vary with time.
Behaviour is how the object reacts to messages, as an example the object might have a good or bad attitude. The behaviour is determined by the class of the object. So you could have GoodyTwoShoes objects with a much too good attitude and BaddAss objects with a bad attitude.
2) What is inheritance? i understand what the word
means, but how can this relate to Java? provide an
example if you can, please.Your GoodyTwoShoes and BaddAss classes could both derive from the same class. For example that class could be TypicalStudent, it would have many common behaviours like eatsLunch, ridesBus, attendsFootballGames, goesOnDates etc. these would be inherited from the TypicalStudent class, but the disruptsClasses and brownNose behaviours would not be inherited.
3)How do threads work? If i wanted to make a a
character that moves around a screen, while another
character is doing the same thing, how would i make
the thread do that?Threads are like small interior processes that appear to run independently, even though they have access to the same memory. So your 2 characters could both access the Window, but would have seperate x and y coordinates and motion attributes. They would appear to move independently because the system would allocate resource to them in turn, just how it does that isn't relevant at your level.
Thanks for all the help.You are welcome, now it's time to hit the books, I suggest you start with "Head First Java", it's comprehensive, fun to read and will teach you a lot. The other books recommended above are all very good, but may be a bit too advanced.