50,528
社区成员
发帖
与我相关
我的任务
分享kotlin中判断装箱后的Int值是不是相等
在kotlin的官方文档上
On the Java platform, numbers are physically stored as JVM primitive types, unless we need a nullable number reference
(e.g. Int? ) or generics are involved. In the latter cases numbers are boxed.
val a: Int = 10000
print(a === a) // Prints 'true'
val boxedA: Int? = a
val anotherBoxedA: Int? = a
print(boxedA === anotherBoxedA) // !!!Prints 'false'!!!
但是把a换成100或是左右的数字则两次都是true???
On the Java platform, numbers are physically stored as JVM primitive types, unless we need a nullable number reference
(e.g. Int? ) or generics are involved. In the latter cases numbers are boxed.
val a: Int = 10000
print(a === a) // Prints 'true'
val boxedA: Int? = a
val anotherBoxedA: Int? = a
print(boxedA === anotherBoxedA) // !!!Prints 'false'!!!
但是把a换成100或是左右的数字则两次都是true???
...全文
请发表友善的回复…
发表回复
jumpAlittle 2018-12-06
- 打赏
- 举报
1楼老哥牛逼
dsj304885103 2017-07-14
- 打赏
- 举报
是Java的Integer缓存机制导致的 具体可参考http://javapapers.com/java/java-integer-cache/
简单解释就是Java把-128到127的数都缓存了 引用这个范围内的数都会指向同一个对象，不在这个范围内的就会遵循装箱的规则了，不是同一个对象，所以你定义的 a 大于127就和官网的demo结果一样了，官网用的10000，明显知道这个“坑”
