split does not return array with the string elements

Question

I’m having trouble using the method split, that is not returning me the array with the elements of the string.

public class Teste{


    public static void main (String[] args){

        String s = "0.101110";

        String[] partes = s.split(".");

        for (int i = 0 ; i < partes.length ; i++){

            System.out.println("Elemento " + (i+1) + ": " + partes[i]);
        }

        System.out.println("tamanho array: " + partes.length);
        System.out.println("string: " + s); 

    }
}

My exit is being:

array size: 0
string: 0.101110

Answer 1

According to the documentation, the method parameter split must be a regular expression.

And as in regular expressions the point has special meaning (means "any character"), he must be escaped with \ to lose this special meaning and be interpreted as the character itself .:

String s = "0.101110";
String[] partes = s.split("\\.");

for (int i = 0; i < partes.length; i++) {
    System.out.println("Elemento " + (i + 1) + ": " + partes[i]);
}

System.out.println("tamanho array: " + partes.length);
System.out.println("string: " + s);

Remembering that within a string the character \ should be written as \\. The exit is:

Element 1: 0
Element 2: 101110
array size: 2
string: 0.101110

---

Another alternative is to use the class java.util.regex.Pattern, that has the method quote, that makes the point escape (i.e., it does not need the \, because the method returns a string already properly escaped):

String[] partes = s.split(Pattern.quote("."));

And a third alternative is to use \Q and \E. Basically, any character between the \Q and \E is interpreted literally, with no special meaning within the expression:

String[] partes = s.split("\\Q.\\E");

Both produce the same result as split("\\.") (which, by the way, is the simplest solution - the two alternatives are useful when you have very large strings with several special characters, because there is less work than escaping one by one with \).