运行时编译时类型 [英] compile time type at runtime

问题描述

Java 中有没有办法在运行时获取引用的编译时类型?

Is there any way in Java to get the compile time type of a reference at runtime?

示例:

private void doSomething(final Object o)
{
   // do somthing
}

final Number n = 1; 
doSomething(n);

final Object o = 1; 
doSomething(o);

final Integer i = 1; 
doSomething(i);

第一个电话 --> 号码

1st call --> Number

第二次调用 --> 对象

2nd call --> Object

第三次调用 --> 整数

3rd call --> Integer

这是问题的一个非常简化的版本.我想要做的是检测(而不是被告知)关于正在传递的对象的框架元数据.可能发生的情况是，该方法首先使用 Integer 调用，然后使用 Double 调用，两者都声明为 Number.

This is a very simplified version of the problem. What i am trying to do is to detect(instead of being told) inside a framework metadata about objects being passed. What could happen is, that the method gets first called with an Integer and then with a Double, both declared as Number.

推荐答案

我看到的唯一方法是使用重载.但是您需要为继承关系的每个类指定一个覆盖方法以排除子类.

The only way I see is to use overloading. But you would need to specify a overlading method for each class of the inheritance relation to exclude sub classes.

private void doSomething(final Object o)
{
   // do something
}

private void doSomething(final Number n)
{
   // do something
}

private void doSomething(final Integer i)
{
   // do something
}

final Number n = 1;
doSomething(n); // doSomething(final Number) is called.

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