What's the point in explicitly throwing exceptions rather than just letting the JVM throw its own?

I'm not sure how it is with other IDEs but in Eclipse if you do something wrong and your program doesn't compile or run Eclipse explicitly highlights what is wrong in the output box in red font. Instead of writingthrow new IllegalStateException() when trying to peek an empty heap or something like that, why not just let Eclipse write out its own errors? Why do you have to explicitly write in your code that you need to throw exceptions at certain places? via /r/javahelp http://ift.tt/2sSC88Z