Question

我已经在构造函数中传递了数据，但是如何在另一个类中获取数据？

class EmployeeConst(var name:String , var age:String) {
    var profession:String ="Not mentioned"

    constructor(name:String, age: String, profession:String):this(name,age){
        this.profession = profession
    }
        fun getDetails() {
            Log.i("",""+"Employee details is $name whose profession is $profession and age is $age")
        }

}

 class FragmentDashboard : Fragment() {

        override fun onCreateView(
            inflater: LayoutInflater, container: ViewGroup?,
            savedInstanceState: Bundle?
        ): View? {
             var person= EmployeeConst("name","sdf","test")
            Log.i("Testings",""+person.getDetails()) //here testings is not printing correctly.

            return inflater.inflate(R.layout.fragment_dashboard, container, false)
        }

在日志中，我没有收到传递的数据

I /测试：kotlin.Unit

Answer 1

实际上，构造函数传递的值不是问题。您的问题是getDetails不返回任何内容，或者在kotlin中，它是一个单位。

这是我创建的改进：首先，删除重载的构造函数，并使用默认的专业值。该方法与重载方法相同，只是它的行短。接下来，我已修复您的getDetails函数以返回字符串。简而言之，等号是“ return this->”的简写，语法为

fun methodNAme() return this -> something

class EmployeeConst(
    var name:String,
    var age:String,
    var profession:String = "Not mentioned"
) {
    fun getDetails() =
        "Employee details is $name whose profession is $profession and age is $age"
}

class FragmentDashboard : Fragment() {
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        var person= EmployeeConst("name","sdf","test")
        Log.i("Testings",""+person.getDetails()) //here testings is not printing correctly.

        return inflater.inflate(R.layout.fragment_dashboard, container, false)
    }
}

Answer 2

由于getDetails()是Unit函数，因此可以正确记录。

在getDetails()中正确记录：

fun getDetails(): Unit {
    Log.i("Testings", "Employee details is $name whose profession is $profession and age is $age")
}

或返回getDetails()中的字符串：

fun getDetails(): String {
    return "Employee details is $name whose profession is $profession and age is $age"
}

Answer 3

方法getDetails()是一个无效函数，即不返回任何内容。当您将此方法称为

Log.i("Testings",""+person.getDetails())

您期望该方法将返回一个字符串。有两种解决方案：

您在Log类中更改了FragmentDashboard：

Log.i("Testings")
person.getDetails()

您更改方法getDetails()的返回值。

fun getDetails(): String {
    return "Employee details is $name whose profession is $profession and age is $age"
}

使用第二种方法，您可以在执行操作时调用该方法。

如何从Kotlin中的构造函数传递值中获取数据

3 个答案: