Sorry for the delay; while I was having dinner everybody else was writing.
Welcome to JavaRanch (
) and what an interesting first question.
The least serious type of error is the compiler error, because you have spelt something wrong, not paired off () [] {} <> correctly, used a variable “out of scope,” etc. etc. There are hundreds of potential causes for compiler errors. These are the best sort, because you find out about them soon and can correct them before they turn into more serious errors. In fact there were complaints that Java used not to support generics; that is a way of converting a runtime error to a compiler error. There are websites about compiler errors e.g.
MindProd and many others.
More serious are runtime errors, which people have already told you about. As people said, most runtime errors show themselves by an Exception. Have a look at the Java™ Tutorials link in the first reply, and bookmark the Tutorials: that’s a good resource.
The most serious of all, because the application can continue to run, are logic errors. They can cause the application to run and
produce a wrong result, which is why they are so dangerous.