Commons Lang、StringUtils.substringBefore()

ほぼ、まんま

import org.apache.commons.lang.StringUtils;

public class C2008112900 {
    public static void main(String[] args) {
        System.out.println(StringUtils.substringBefore(null, "z"));
        System.out.println(StringUtils.substringBefore("", "z"));
        System.out.println(StringUtils.substringBefore("abc", "a"));
        System.out.println(StringUtils.substringBefore("abcba", "b"));
        System.out.println(StringUtils.substringBefore("abc", "c"));
        System.out.println(StringUtils.substringBefore("abc", "d"));
        System.out.println(StringUtils.substringBefore("abc", ""));
        System.out.println(StringUtils.substringBefore("abc", null));

        System.out.println(StringUtils.substringBefore("abc", "bc"));
    }
}

で、

null


a
ab
abc

abc
a