Jakarta Commons Cookbook

2.13. Parsing Formatted Strings

Problem

You need to parse a string containing control characters and the delimiters (, [, ), ], and ,.

Solution

Use variations of substring() from StringUtils. This next example parses a string that contains five numbers delimited by parentheses, brackets, and a pipe symbol (N0 * (N1,N2) [N3,N4] | N5):

String formatted = " 25 * (30,40) [50,60] | 30"

PrintWriter out = System.out;
out.print("N0: " + StringUtils.substringBeforeLast( formatted, "*" ) );
out.print(", N1: " + StringUtils.substringBetween( formatted, "(", "," ) );
out.print(", N2: " + StringUtils.substringBetween( formatted, ",", ")" ) );
out.print(", N3: " + StringUtils.substringBetween( formatted, "[", "," ) );
out.print(", N4: " + StringUtils.substringBetween( formatted, ",", "]" ) );
out.print(", N5: " + StringUtils.substringAfterLast( formatted, "|" ) );

This parses the formatted text and prints the following output:

N0: 25, N1: 30, N2: 40, N3: 50, N4: 60, N5: 30

Discussion

The following public static methods come in handy when trying to extract information from a formatted string:

StringUtils.substringBetween( )

Captures content between two strings

StringUtils.substringAfter( )

Captures content that occurs after the specified string

StringUtils.substringBefore( )

Captures content that occurs before a specified string

StringUtils.substringBeforeLast( )

Captures content after the last occurrence of a specified string

StringUtils.substringAfterLast( )

Captures content before the last occurrence ...