Splitting a String with the pipe symbol as delimiter

Question

Why is it that in the following, the output is [] and not [1]?

String input="1|2|3";
String[] values= input.split("|");
System.out.println("[" + values[0] + "]");
// Output: []

However, if we change the separator, the output is [1].

String input="1;2;3";
String[] values= input.split(";");
System.out.println("[" + values[0] + "]");
// Output: [1]

Answer 1

Try to escape that character:

String input="1|2|3";
String[] values= input.split("\\|");
System.out.println("[" + values[0] + "]");

Answer 2

Because the | has special meaning in regular expressions. You need to escape it like this: \| and in Java you also have to escape the backslash as well so you end up with \\|

The pipe character is a disjunction operator which means that it tells the regular expression engine to choose either pattern on the left and right of it. In your case those where empty strings which match anything.

Answer 3

The split method receives a regex as a parameter. The pipe is a reserved character with its own purpose (it means or).

You can either escape it ("\\|") or, if you're in Java 1.5+ you can use Pattern.quote("|") like this:

input.split(Pattern.quote("|"));

Answer 4

Try using \\| instead of | when you split as you need to escape it.

So your code would change to:

String input="1|2|3";
String[] values= input.split("\\|");
System.out.println("[" + values[0] + "]");

Answer 5

you have to escape the character '|' properly

String input="1|2|3";
        String[] values= input.split("\\|");
        System.out.println("[" + values[0] + "]");