[英]Does int.class equal Integer.class or Integer.TYPE in Java?
Let's imagine one retrieves the declaring type of a Field
using reflection. 让我们假设一个人使用反射检索一个Field
的声明类型。
Which of the following tests will correctly indicate whether one is dealing with an int
or an Integer
? 以下哪个测试将正确指示是否正在处理int
或Integer
?
Field f = ...
Class<?> c = f.getDeclaringClass();
boolean isInteger;
isInteger = c.equals(Integer.class);
isInteger = c.equals(Integer.TYPE);
isInteger = c.equals(int.class);
isInteger = ( c == Integer.class);
isInteger = ( c == Integer.TYPE);
isInteger = ( c == int.class);
Based on Field.getType()
(instead of f.getDeclaringClass()
), I get the following: 基于f.getDeclaringClass()
Field.getType()
(而不是f.getDeclaringClass()
),我得到以下内容:
Type: java.lang.Integer
equals(Integer.class): true
equals(int.class) : false
equals(Integer.TYPE) : false
== (Integer.class) : true
== (int.class) : false
== (Integer.TYPE) : false
Type: int
equals(Integer.class): false
equals(int.class) : true
equals(Integer.TYPE) : true
== (Integer.class) : false
== (int.class) : true
== (Integer.TYPE) : true
Type: java.lang.Object
equals(Integer.class): false
equals(int.class) : false
equals(Integer.TYPE) : false
== (Integer.class) : false
== (int.class) : false
== (Integer.TYPE) : false
Meaning the following is true: 含义如下:
Integer.TYPE.equals(int.class)
Integer.TYPE == int.class
Meaning if I want to find out whether I am dealing with an int
or an Integer
, I can use any of the following tests: 这意味着如果我想知道我是在处理int
还是Integer
,我可以使用以下任何一个测试:
isInteger = c.equals(Integer.class) || c.equals(Integer.TYPE);
isInteger = c.equals(Integer.class) || c.equals(int.class);
isInteger = (c == Integer.class) || (c == Integer.TYPE);
isInteger = (c == Integer.class) || (c == int.class );
Is there a corner case I am missing? 我错过了一个角落案例吗? If yes, please comment. 如果是,请发表评论。
int.class
compiles down to Integer.TYPE
. int.class
编译为Integer.TYPE
。 However, I think you are using Field.getDeclaringClass()
incorrectly, as this returns the Class
object representing the class that declares the field. 但是,我认为您正在错误地使用Field.getDeclaringClass()
,因为它返回表示声明该字段的类的Class
对象。 What you would want to use is Field.getType()
. 你想要使用的是Field.getType()
。
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