先使用checkNotNull(name, {"变量为空"})先决条件函数 , 判定name是否为空 , 如果为空 , 抛出带信息的IllegalStateException异常 信息 ; 代码语言:javascript 代码运行次数:0 运行 AI代码解释 funmain(){varname:String?=null// 捕获并处理异常try{checkNotNull(name,{"变量为空"})name!!.count();}catch(...
而且一定需要这个参数，那么在新的目标activity中 onCreate方法中 判断中这个参数，如果null，直接抛出空指...
Learn how to effectively check for undefined values in JavaScript. Explore methods and best practices to handle undefined variables in your code.
Is null false in JavaScript? Null is not considered false in JavaScript, but it is considered falsy. This means that null is treated as if it’s false when viewed through boolean logic. However, this is not the same thing as saying null is false or untrue. ...
文章分类 JavaScript 前端开发 1、CONSTRAINT 约束种类 为了确保数据的完整性和唯⼀性,关系型数 据库通过约束机制来实现目。(关于索引和约束的联系可以简单理解为创建约束不一定创建索引,但是创建索引如唯一、非空等索引会同时创建相应的的约束) UNIQUE 唯一性约束 值不可重复; NOT NULL 非空约束 值不可为空; ...
JavaScript recognizes false, 0, -0, 0n, "", null, undefined, and NaN as falsy.To verify that all values in an array are falsy, you can again use the every() method, but this time with a function that checks for falsy values:...
Then inside one of your JavaScript scripts you can do (for example): function myFunc(a) { Integrity.checkIsValidNumber(a, "a is not a number, it was {}", a) } Integrity API The full set of functions is: Integrity.check(condition, *msg) ...
check.object(thing): Returnstrueifthingis a plain-old JavaScript object,falseotherwise. check.emptyObject(thing): Returnstrueifthingis an empty object,falseotherwise. check.nonEmptyObject(thing): Returnstrueifthingis a non-empty object,falseotherwise. ...
CREATETABLEusers(idINTAUTO_INCREMENTPRIMARYKEY,nameVARCHAR(100)NOTNULL,genderENUM('男','女')NOTNULL,ageINT,CHECK(genderIN('男','女'))); 1. 2. 3. 4. 5. 6. 7. 在上述代码中: id是自增的主键。 name是用户姓名,不能为空。 gender是性别字段,使用ENUM数据类型仅允许 “男” 和 “女”。
let a = null; console.log(_.isNull(a)); // true console.log(_.isUndefined(a)); // false console.log(_.isNil(a)); // true Conclusion In this short guide, we've taken a look at how to check if a variable is null, undefined or nil in JavaScript, using the ==, === and...