kotlin

Question

我在尝试理解以下代码中发生的事情时遇到了一些困难：

fun helperMethodNameA(someId: String, rules: RulesObject) {
    val content = JsonNodeFactory.instance.arrayNode().apply { // A & B
        add(JsonNodeFactory.instance.objectNode().apply {
            set("body", JsonNodeFactory.instance.objectNode().apply { // C
                set("text", JsonNodeFactory.instance.objectNode().apply { // D
                    set("value", JsonNodeFactory.instance.textNode(mapper.writeValueAsString(rules))) // E
                })
            })
        })
    }
    return helperMethodNameB(someId, content.toString())
}

这个项目依赖于另一个设置了 Kotlin v1.3.20 的项目。依赖项目将 Kotlin 版本提升到 v1.3.60。根据以下内容，此位因更新而中断：

A - [ERROR] <pathToFile> [line, position] Type inference failed: inline fun <T> T.apply(block: T.() -> Unit): T
    [ERROR] cannot be applied to
    [ERROR] receiver: ArrayNode!  arguments: (ArrayNode!.() -> ArrayNode!)
B - [ERROR] <pathToFile> [line, position] Type mismatch: inferred type is ArrayNode!.() -> ArrayNode! but ArrayNode!.() -> Unit was expected
C - [ERROR] <pathToFile> [line, position] Type inference failed: Not enough information to infer parameter T in operator fun <T : JsonNode!> set(p0: String!, p1: JsonNode!): T!
    [ERROR] Please specify it explicitly.
D - [ERROR] <pathToFile> [line, position] Type inference failed: Not enough information to infer parameter T in operator fun <T : JsonNode!> set(p0: String!, p1: JsonNode!): T!
    [ERROR] Please specify it explicitly.
E - [ERROR] <pathToFile> [line, position] Type inference failed: Not enough information to infer parameter T in operator fun <T : JsonNode!> set(p0: String!, p1: JsonNode!): T!
    [ERROR] Please specify it explicitly.

我在这里错过了什么？

Answer 1

解决方案是按以下方式指定类型：

fun helperMethodNameA(someId: String, rules: RulesObject) {
    val content = JsonNodeFactory.instance.arrayNode().apply { 
        add(JsonNodeFactory.instance.objectNode().apply {
            set<ObjectNode>("body", JsonNodeFactory.instance.objectNode().apply { 
                set<ObjectNode>("text", JsonNodeFactory.instance.objectNode().apply { 
                    set<TextNode>("value", JsonNodeFactory.instance.textNode(mapper.writeValueAsString(rules)))
                })
            })
        })
    }
    return helperMethodNameB(someId, content.toString())
}

kotlin - 更新 kotlin 版本时的类型推断和类型不匹配

kotlin - type inference and type mismatch when updating kotlin version

type-inference

type-mismatch