Exception throwing point

Question

What is the point of throwing exceptions? For example, I came across this:

static List<Integer> list(int [] a) {
    if (a == null)
        throw new NullPointerException();
        //...

But when you don't drop nullpointer, will you also get nullpointer? I see it regularly, and I would like to know if it is good to study?

Answer 1

Better to fail quickly. For example, a function can do a bunch of stuff before it even refers to the variable "a" in your example, which leads to a lot of unnecessary processing. It would be best to crash right away if you know that "a" is null from the very beginning. You can also add a special error message to the exception.

Answer 2

THROW , .

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, , .

Answer 3

, . , , -, , . - . , ...

FlowControl → GenericMethod ( ) → PrivateMethods ( , ).

: Exception vs ?

Answer 4

, - , . , "ToList", :

static List<Integer> list(int[] a)
{
    List<int> ret = new List<int>();
    foreach (int i in a)
        ret.add(i);
    return ret;
}

, , ( , , , # , foreach). , throw, .

Answer 5

, -, . ( - null, null), ( , ) .

Basically, when you arbitrarily throw exceptions, each person using your library, for example, can save the correct thread.