Java StringUtils.stripEnd 带句点、连字符或下划线

Question

I'm trying to strip trailing characters off of a string using StringUtils.stripEnd , and noticed if I try to strip "_FOO" from "FOO_FOO" , this returns an empty string. For example,

import org.apache.commons.lang3.StringUtils;

public class StripTest {

    public static void printStripped(String s1, String suffix){
        String result = StringUtils.stripEnd(s1, suffix);
        System.out.println(String.format("Stripping '%s' from %s  -->   %s", suffix, s1, result));
    }

    public static void main(String[] args) {
        printStripped("FOO.BAR", ".BAR");
        printStripped("BAR.BAR", ".BAR");
        printStripped("FOO_BAR", "_BAR");
        printStripped("BAR_BAR", "_BAR");
        printStripped("FOO-BAR", "-BAR");
        printStripped("BAR-BAR", "-BAR");
    }

}

Which outputs

Stripping '.BAR' from FOO.BAR  -->   FOO
Stripping '.BAR' from BAR.BAR  -->   
Stripping '_BAR' from FOO_BAR  -->   FOO
Stripping '_BAR' from BAR_BAR  -->   
Stripping '-BAR' from FOO-BAR  -->   FOO
Stripping '-BAR' from BAR-BAR  -->   

Can someone explain this behavior? Didn't see any examples from docs of this case. Using Java 7.

Answer 1

Look at the documentation and examples present in the StringUtils Javadoc:

Strips any of a set of characters from the end of a String.

A null input String returns null. An empty string ("") input returns the empty string.

If the stripChars String is null, whitespace is stripped as defined by Character.isWhitespace(char).

 StringUtils.stripEnd(null, *)          = null
 StringUtils.stripEnd("", *)            = ""
 StringUtils.stripEnd("abc", "")        = "abc"
 StringUtils.stripEnd("abc", null)      = "abc"
 StringUtils.stripEnd("  abc", null)    = "  abc"
 StringUtils.stripEnd("abc  ", null)    = "abc"
 StringUtils.stripEnd(" abc ", null)    = " abc"
 StringUtils.stripEnd("  abcyx", "xyz") = "  abc"
 StringUtils.stripEnd("120.00", ".0")   = "12"

This is not what you want, as it will strip the SET of characters anywhere from the end. I believe you are looking for removeEnd(...)

Removes a substring only if it is at the end of a source string, otherwise returns the source string.

A null source string will return null. An empty ("") source string will return the empty string. A null search string will return the source string.

 StringUtils.removeEnd(null, *)      = null
 StringUtils.removeEnd("", *)        = ""
 StringUtils.removeEnd(*, null)      = *
 StringUtils.removeEnd("www.domain.com", ".com.")  = "www.domain.com"
 StringUtils.removeEnd("www.domain.com", ".com")   = "www.domain"
 StringUtils.removeEnd("www.domain.com", "domain") = "www.domain.com"
 StringUtils.removeEnd("abc", "")    = "abc"

removeEnd(...) operates not a set of characters, but instead a substring, which is what you are trying to extract.