Kotlin中的Map分為：

只讀Map。
可變的MutableMap(MutableMap、HashMap、LinkedHashMap)。

Map源碼：

private object EmptyMap : Map<Any?, Nothing>, Serializable {private const val serialVersionUID: Long = 8246714829545688274override fun equals(other: Any?): Boolean = other is Map<*,*> && other.isEmpty()override fun hashCode(): Int = 0override fun toString(): String = "{}"override val size: Int get() = 0override fun isEmpty(): Boolean = trueoverride fun containsKey(key: Any?): Boolean = falseoverride fun containsValue(value: Nothing): Boolean = falseoverride fun get(key: Any?): Nothing? = nulloverride val entries: Set<Map.Entry<Any?, Nothing>> get() = EmptySetoverride val keys: Set<Any?> get() = EmptySetoverride val values: Collection<Nothing> get() = EmptyListprivate fun readResolve(): Any = EmptyMap }

創建只讀Map

val mMap = mapOf(0 to "秦", 1 to "川", 2 to "小", 3 to "將") println(mMap)

打印輸出：

{0=秦, 1=川, 2=小, 3=將}

創建可變Map

mutableMapOf

val mMap = mutableMapOf(0 to "秦", 1 to "川", 2 to "小", 3 to "將") println("=========向Map中添加元素kotlin,in,android===========") mMap.put(4, "kotlin") mMap.put(5, "in") mMap.put(6, "android") println(mMap) println("===========將Map中元素android替換為java=============") mMap.replace(6, "java") println(mMap) println("===========刪除Map中元素kotlin,in,java=============") mMap.remove(4, "kotlin") mMap.remove(5, "in") mMap.remove(6, "java") println(mMap) println("================清除Map中所有元素===================") mMap.clear() println(mMap.size)

打印輸出：

=========向Map中添加元素kotlin,in,android=========== {0=秦, 1=川, 2=小, 3=將, 4=kotlin, 5=in, 6=android} ===========將Map中元素android替換為java============= {0=秦, 1=川, 2=小, 3=將, 4=kotlin, 5=in, 6=java} ===========刪除Map中元素kotlin,in,java============= {0=秦, 1=川, 2=小, 3=將} ================清除Map中所有元素=================== 0

hashMapOf

val mMap = hashMapOf(0 to "秦", 1 to "川", 2 to "小", 3 to "將") println(mMap)

打印輸出：

{0=秦, 1=川, 2=小, 3=將}

linkedMapOf

val mMap = linkedMapOf(0 to "秦", 1 to "川", 2 to "小", 3 to "將") println(mMap)

打印輸出：

{0=秦, 1=川, 2=小, 3=將}

sortedMapOf

sortedMapOf(vararg pairs: Pair

val mMap = sortedMapOf(1 to "川", 3 to "將", 0 to "秦", 2 to "小") println(mMap)

打印輸出：

{0=秦, 1=川, 2=小, 3=將}

遍歷Map

使用forEach遍歷

val mMap = mutableMapOf(0 to "秦", 1 to "川", 2 to "小", 3 to "將") mMap.entries.forEach {print("" + it.key + " " + it.value + " ") }

打印輸出：

0 秦
1 川
2 小
3 將

總結

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