Kotlin数据去重实现distinctBy源码

摘自Kotlin源码

package kotlin.collections
/**
 * Returns a list containing only elements from the given collection
 * having distinct keys returned by the given [selector] function.
 * 
 * The elements in the resulting list are in the same order as they were in the source collection.
 */
public inline fun <T, K> Iterable<T>.distinctBy(selector: (T) -> K): List<T> {
    val set = HashSet<K>()
    val list = ArrayList<T>()
    for (e in this) {
        val key = selector(e)
        if (set.add(key))
            list.add(e)
    }
    return list
}						

示例：根据实体类中的某个字段过滤去重

	//数据类
	data class AlarmBean( var alarmCreatedTimestamp: Long = 0 )
	//创建集合
	val list = mutableListOf<AlarmBean>()
	//过滤去重字段
	list.distinctBy { it.alarmCreatedTimestamp }