为什么 Integer a=10 是 java 中的有效语句? [英] Why is Integer a=10 a valid statement in java?

问题描述

据我所知，Integer 是 int 的包装类.所以必须创建一个对象来初始化 a 的值.

As far as I know, Integer is a wrapper class for int. So an object must be created for initializing value of a.

Integer x=new Integer(10);

但是 Integer x=10; 似乎工作得很好.有人可以解释一下吗?

But Integer x=10; seems to work perfectly. Can someone please explain how?

推荐答案

感谢自动装箱.

自动装箱是 Java 编译器在原始类型与其对应的对象包装类之间进行的自动转换.例如，将 int 转换为 Integer，将 double 转换为 Double，等等.如果转换方向相反，则称为拆箱.

Autoboxing is the automatic conversion that the Java compiler makes between the primitive types and their corresponding object wrapper classes. For example, converting an int to an Integer, a double to a Double, and so on. If the conversion goes the other way, this is called unboxing.

参见文档 https://docs.oracle.com/javase/tutorial/java/data/autoboxing.html

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