CODEWITHSUNDEEP
javaswitch-statement
GregD
GregD

Reputation: 1944

switch behaviour - java

Why doens't the following code throw a runtimeException?

public class Test2 extends Test {


public static void main(String[] args) {
    char[] array = new char[]{'A', '\t', 'e', 'I', 'O', 'u', '\n', 'p'};

    int count = 0;
    for (char c : array) {
        switch (c) {
            case 'A':
                continue;
            case 'E':
                count++;
                break;
            case 'I':
                count++;
                continue;
            case 'o':
                break;
            case 'u':
                count++;
                continue;
        }
    }
    System.out.println("length of array: " + array.length);
    System.out.println("count= " + count);
}

}

notice that 'E' and 'e' isn't equal and it is in the switch.. The same for 'p'. It does compile and run en prints: length of array: 8 count= 2

I completed my OCA certificate today and got the above question. But I can't figure out why it doesn't throw a runtime when 'e' or 'p' is checked.. This means there is an empty "default" in every switch or something?

Upvotes: 1

Views: 116

Answers (2)

AlexR
AlexR

Reputation: 115388

Why do you expect any exception here? If value of c is not mentioned in any case statement nothing happens on current iteration of your loop, switch passes through and loop is going to the next iteration.

Upvotes: 1

Jon Skeet
Jon Skeet

Reputation: 1503310

This means there is an empty "default" in every switch or something?

Sort of. If no case matches the specified value, and there's no default case, nothing happens - it's as simple as that.

From section 14.11 of the JLS:

If no case matches and there is no default label, then no further action is taken and the switch statement completes normally.

I wouldn't personally have expected an exception here - I don't think I've ever worked with a language which would throw an exception in a similar language construct, though I dare say one may exist.

Upvotes: 8

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