Split string in Java

There are a lot of time to split string type when you are writing program. Of course in Java. Although I already know split method in String can be applied to this case, I misunderstood how to use it. My initial code is below.

public class Split {
    public static void main(String[] args) {
        String s = "foo.bar";
        System.out.println(s.split(".")[0]);
        System.out.println(s.split(".")[1]);
    }
}

And running this threw such exception.

$ java Split
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at Split.main(Split.java:4)

It looks split method does not work properly. What happend? The answer is in javadoc about String.

String#split

String#split must receive regex type as String. So in this case “.” interpreted as “Match any one character” in regular expression context. I had to write argument as “Only dot character” when passes to split method. I rewritten it.

public class Split {
    public static void main(String[] args) {
        String s = "foo.bar";
        System.out.println(s.split("\\.")[0]);
        System.out.println(s.split("\\.")[1]);
    }
}

$ java Split
foo
bar

Yes. It’s working now. I learned javadoc is one of the most useful resource to all java developers. I want to be not reluctant to look into official documents such as javadoc of JDK from now.

Thank you.