[移动开发]kotlin out 和in 使用示例

import org.junit.Test

class TestKotlin {

    interface Source<out T> {
        fun nextT(): T
    }

    @Test
    fun testOut() {
        val a = object: Source<Number>{
            override fun nextT(): Number {
                return  100
            }
        }
        val  o: Source<Any> = a
    }

    interface Source2<in T> {
        fun process(t: T)
    }

    @Test
    fun testIn() {
        val a = object: Source2<Number>{
            override fun process(t: Number) {
                println(t)
            }
        }

        val  o: Source2<Int> = a

    }
  }