Safe guard: just like Typescript, you can use ? to type safe check: var strnull: String? =nullprint(strnull?.length)//null If strnull is null, then print null, if not null, then print its length !!: If you are sure that your variable is not null, then you can do: var str = "wan"print(str!!.length) // 3 If 'str' is...
//查看是否及格 fun main(args : Array<String>){ check_score(59) check_score(61) } //检查分数是否合格, 大于等于 60 分合格, 否则 不合格 fun check_score(score : Int) : Boolean{ var is_pass : Boolean if(score >= 60){ println("及格") is_pass = true }else{ println("不及格") is...
因为strB可能为空,会扔出空指针异常length=if(strB!=null)strB.lengthelse-1tv_check_result.text="字符串B的长度为$length"}btn_length_c.setOnClickListener{//即使strC实际有值,也必须做非空判断
The internalVariable is assigned as part of its declaration, does not have any annotations (like @Autowired, etc.), and works fine when I remove the @Transactional annotation and the requirement for Spring to proxy the class. Why is this variable null when Spring is proxying/subclassing my se...
var strNotNull:String = "" 非空对象要么在声明时就赋值,要么在方法调用前赋值;否则未经初始化就调用该对象的方法,Kotlin会像语法错误那样提示这里“Variable *** must be initialized”。至于可以为空的对象,可于声明之时在类型后面加个问号,如同上一篇文章声明可空字符串数组的代码“val poem2Array:Array<Strin...
LOCALVARIABLE b I L0 L2 1 MAXSTACK = 2 MAXLOCALS = 2 } kotlin 源码: packagecom.xxxx.kotlinclassSDK{}funaddSum(a:Int,b:Int):Int{println("run in kotlin sdk!")returna+b;} kotlin字节码: // ===com/xxxx/kotlin/SDK.class === // class version 52.0 (52) // access ...
varresource: Resource? =null// Not acquired yet try{ withTimeout(60) {// Timeout of 60 ms delay(50)// Delay for 50 ms resource = Resource()// Store a resource to the variable if acquired } // We can do something else with the resource here ...
just like Typescript, you can use ? to type safe check: var strnull: String? =nullprint(strnull?.length)//null 1. 2. If strnull is null, then print null, if not null, then print its length !!: If you are sure that your variable is not null, then you can do: ...
Although not-null, immutable variables with sensible defaults are often desired, it is not always the case. It is sometimes required to check if multiple
var strNotNull:String ="" 非空对象要么在声明时就赋值,要么在方法调用前赋值;否则未经初始化就调用该对象的方法,Kotlin会像语法错误那样提示这里“Variable *** must be initialized”。至于可以为空的对象,可于声明之时在类型后面加个问号,如同上一篇文章声明可空字符串数组的代码“val poem2Array:Array<String...