Why Does Java's `split()` Method Fail When Splitting Strings by '|' and How Can I Fix It?

Splitting a Java String by the Pipe Symbol: Troubleshooting the Ineffective Split() Method

The Java split() method, when used to divide a string by the pipe symbol ("|"), can yield unexpected results, as seen in the following example:

public static void main(String[] args) {
    String test = "A|B|C||D";

    String[] result = test.split("|");

    for (String s : result) {
        System.out.println(">"+s+"<");
    }
}

Instead of the intended output:

>A<
>B<
>C<
><
>D<

the code produces:

><
>A<
>|
>B<
>|
>C<
>|
>|
>D<

Why does this occur?

The problem lies in the syntax of the split() method. The pipe symbol, "|", holds special significance in regular expressions, where it represents the "OR" operator. To use the pipe symbol literally as a delimiter, it must be escaped using a backslash ().

To amend the code, one can use the following approaches:

// Option 1: Escaping the pipe symbol
String[] result = test.split("\|");

// Option 2: Utilizing Pattern.quote()
import java.util.regex.Pattern;
String[] result = test.split(Pattern.quote("|"));

By escaping the pipe symbol, you suppress its special status in regular expressions, allowing it to be interpreted as a literal delimiter.

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