kotlin字符串判空
Given a string, we have to check whether it is an empty, blank or NULL string.
给定一个字符串，我们必须检查它是否为空，空白或NULL字符串。
Example:
例：
Input:str = ""Output:True
用于在Kotlin中检查Empty，Blank或NULL字符串的程序 (Program to check for Empty, Blank or NULL string in Kotlin)
package com.includehelp.basic//Main Function, entry Point of Programfun main(args: Array<String>) {///Nullable Stringval s1: String?=null//Empty Stringval s2: String=""//Blank String, Contained only white spacesval s3=" "println("String s1 is isNullOrEmpty : ${s1.isNullOrEmpty()}")println("S
