java如何验证kotlin中的数据类是否为null

Question

我有一个数据类（如下所示）

data class Request(val containerType: String,
                   val containerId: String)

在下面给出的另一个函数中，我将其作为参数调用

fun someLogicalFunction(request: Request) {
    // validate if request is not null here
    if(request == null) { // i know this is wrong, what can be done for this?
        // do something
    } else { // do something }
}

如何直接在kotlin中检查请求是否为空

Answer 1

someLogicalFunction的参数类型是不可为空的（与Request的属性相同），因此如果从Kotlin代码调用它，您可以在编译时保证不会给出空值，并且不需要进行空检查

然而，如果你真的想/需要允许空值，我建议这样做

data class Request(val containerType: String?,
                   val containerId: String?) {
    val isValid get() = containerId != null && containerType != null
}

fun someLogicalFunction(request: Request?) {
    request?.let{
        if (request.isValid) {
            val type = request.containerType!!
            val id = request.containerId!!
            // do something
            return //this will return out of someLogicalFunction
        }
    }
    //we will only execute code here if request was null or if we decided it was invalid
}

显然，用对任何需要都有意义的东西来替换isValid实现