kotlin 中的接口回调不需要类型参数

Question

val apiInterface: ApiInterface =
        ApiClient().getApiClient()!!.create<ApiInterface>(ApiInterface::class.java) ?:
    val call: Call<Contacts?>? = apiInterface.signUp(username, contact, password)
    call.enqueue(object : Callback<Contacts?>() {
        fun onResponse(call: Call<Contacts?>?, response: Response<Contacts?>) {
            val value: String = response.body().getValue()
            val message: String = response.body().getMassage()
            if (value == "success") {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
                val intent = Intent(this@SignUpActivity, LoginActivity::class.java)
                startActivity(intent)
            } else if (value == "exists") {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
            } else {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
            }
        }

        fun onFailure(call: Call<Contacts?>?, t: Throwable) {
            
            Toast.makeText(this@SignUpActivity, "Error! $t", Toast.LENGTH_SHORT).show()
        }
    })

错误：No type arguments expected for class Call 我在 <Contacts?> 上收到上述错误我是 Kotlin 的新手所以，我不知道为什么我会收到错误。

我已经从我的 Java 类转换了上面的源代码。 这是我的Java code。

val apiInterface: ApiInterface =
        ApiClient().getApiClient()!!.create<ApiInterface>(ApiInterface::class.java)
    val call: retrofit2.Call<Contacts?>? = apiInterface.signUp(username, contact, password)
    call?.enqueue(object : Callback<Contacts?>() {
        override fun onResponse(call: retrofit2.Call<Contacts?>?, response: Response<Contacts?>) {
            val value: String = response.body()?.getValue()!!
            val message: String = response.body()?.getMassage()!!
            if (value == "success") {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
                val intent = Intent(this@SignUpActivity, LoginActivity::class.java)
                startActivity(intent)
            } else if (value == "exists") {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
            } else {
                Toast.makeText(this@SignUpActivity, message, Toast.LENGTH_SHORT).show()
            }
        }

        override fun onFailure(call: retrofit2.Call<Contacts?>?, t: Throwable) {
            
            Toast.makeText(this@SignUpActivity, "Error! $t", Toast.LENGTH_SHORT).show()
        }
    })

Current error

错误：This class does not have a constructor

Answer 1

你能显示进口吗？ 必须是import retrofit2.Call; 而不是其他的。

另外，需要删除第二行的?:

我建议你阅读 Kotlin 中的 elvis 运算符和 null 安全性（关于如何使用这个 ?、?:、!!）[ link ]