android - Kotlin 代码从可变列表中删除一种特定类型的重复对象

Question

我想从列表中删除一种类型的所有重复对象。

例如。

 val models: MutableList<Model> = MutableList<DrawableModel>
 models.add(Student)
 models.add(Student)
 models.add(Teacher)
 models.add(Teacher)
 models.add(Teacher)

预期输出:

Student
Student
Teacher

我只想要列表中一位老师的实例。

我试过

models.distinctBy{ it is Teacher}

但它对整个列表而不是特定对象应用 distinct 并返回。

Student
Teacher

Answer 1

你可以尝试这样的事情:

object Kotlin
{
    @JvmStatic
    fun main(args: Array<String>)
    {
        val teacher = Teacher(0, "T1");
        val student = Student(1, "S1")

        val models = mutableListOf(teacher, teacher, student, student, student)
        
        // creating new list which is connection of two lists. First -> only Students. Second -> Distinct Teacher
        val newModels = models.filterIsInstance<Teacher>().distinct() + models.filterIsInstance<Student>()

        println(models) // [Teacher(ID=0, name=T1), Teacher(ID=0, name=T1), Student(ID=1, name=S1), Student(ID=1, name=S1)]
        println(newModels) // [Teacher(ID=0, name=T1), Student(ID=1, name=S1), Student(ID=1, name=S1)]
}

// classes like in the question.
open class Model(val id: Int)

data class Teacher(val ID: Int, val name: String) : Model(ID)

data class Student(val ID: Int, val name: String) : Model(ID)

所以基本上它是主要部分:

val newModels = models.filterIsInstance<Teacher>().distinct() + models.filterIsInstance<Student>()