实用工具：Apache StringUtils - GongSoSn/Renjianyong GitHub Wiki

 1.isEmpty(CharSeqences CS) : 判断字符序列CS中是不是存在“null”或者""(空);      

          它是会处理null的。

      eg:
          StringUtils.isEmpty(null)      = true
          StringUtils.isEmpty("")        = true
          StringUtils.isEmpty(" ")       = false//不是"",而是" "
          StringUtils.isEmpty("bob")     = false
          StringUtils.isEmpty("  bob  ") = false

Code:

    @Test
    public void isEmptyTest() {
        String test01 = "";
        String test02 = null;
        String test03 = " AB";
        System.out.println("API isEmpty : " + test01.isEmpty());
        // System.out.println("API isEmpty : " + test02.isEmpty());
        System.out.println("API isEmpty : " + test03.isEmpty());
        System.out.println("****************************");
        System.out.println("StringUtils isEmpty : " + StringUtils.isEmpty(test01));
        System.out.println("StringUtils isEmpty : " + StringUtils.isEmpty(test02));
        System.out.println("StringUtils isEmpty : " + StringUtils.isEmpty(test03));
    }