[Java] StringUtils.defaultIfEmpty() 判斷空值並直接回傳預設值

StringUtils.defaultIfEmpty(String str, String defaultStr)

如果空值，則回傳預設 defaultStr 

str = "" → return defaultStr

str != "" → return str

例子：

String str, defaultStr, result;
str = "";
defaultStr = "123";
result = StringUtils.defaultIfEmpty(str, defaultStr);   //123

str = "abc";
defaultStr = "123";
result = StringUtils.defaultIfEmpty(str, defaultStr);	//abc

以往：

String str, defaultStr, result;
str = "";
defaultStr = "123";
if (str.equals("")) result = defaultStr;    //123
else result = str;
		
str = "abc";
defaultStr = "123";
if (str.equals("")) result = defaultStr;
else result = str;                          //abc

defaultIfEmpty() 原始碼：

public static <T extends CharSequence> T defaultIfEmpty(T str, T defaultStr)
{
   return isEmpty(str) ? defaultStr : str;
}