数字提升和平等？
可能的重复：
包装类和 == 运算符
我有一个来自朋友的谜题。就是这样：
public class Test{
public static void main(String[] args){
Integer i = 1000; //10
Integer y = 1000; //10
System.out.println(i == y);
}
}
结果将为 FALSE。这是正确的。但当将 i,y 值替换为 10 时，结果为 TRUE。
据我所知，当运算符 == 应用于引用变量时，它将测试它们是否引用同一个对象。我不知道为什么会出现这样的结果，但我猜测是数字提升的问题。我真的需要帮助。 感谢每一位。
Possible Duplicate:
Wrapper class and == operator
I have a puzzle from my friend. Here is it:
public class Test{
public static void main(String[] args){
Integer i = 1000; //10
Integer y = 1000; //10
System.out.println(i == y);
}
}
The result will be FALSE. That's right. But when replacing the i,y value by 10, the result is TRUE.
From what I've read, when the operator == is applied to reference variables, it will test whether they refer to the same object. I don't know why the results like that, but I guess the problem in numeric promotion. I really need a help.
Thank every one.
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没有任何提升，因为 10 和 1000 作为数字文字，属于 int 类型。
但是有一个针对小整数对象的值池，类似于字符串池，因为大多数值都很小，或者更频繁地使用小值。但为了限制池的大小，它只涵盖 -128 到 127 之间的一些值。
根据经验：对于对象，始终将它们与 equals 进行比较，仅将基本类型与 == 进行比较。
There is nothing promoted, since 10 and 1000, as numeric literal, are of type int.
But there is a value pool for small Integer-Objects, similar to the stringpool, since most values are small, or small values are used more often. But to limit the size of the pool, it only covers some values between -128 and 127.
As a rule of thumb: For Objects, always compare them with equals, only elementary types with ==.