Java 将 int 传递给以 Integer 作为参数的方法？
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Passing int to a method taking Integer as parameter?
提问by Varun
Is it Ok to pass int to a method which is taking Integer as parameter. Here is the code
将 int 传递给将 Integer 作为参数的方法是否可以。这是代码
public class PassingInt
{
public static void main(String args[])
{
int a = -1;
passIntToInteger(a);//Is this Ok?
}
private static void passIntToInteger(Integer a)
{
System.out.println(a);
}
}
采纳答案by peter.petrov
Yes, it is OK, it will be auto-boxed.
是的，没关系，它会自动装箱。
The reverse is also OK and is called auto unboxing.
反过来也可以，称为自动拆箱。
More info here:
更多信息在这里：
回答by Christian
Yes, it is.
是的。
Why?Because of auto-boxing. Primitives are converted to an object of its corresponding wrapper class. From Java Tutorials:
为什么？因为自动装箱。原语被转换为其相应包装类的对象。来自Java 教程：
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.
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。
In your case:
在你的情况下：
primitive type: int -> wrapper class: Integer
回答by Elliott Frisch
Yes, in your example it would be autoboxed(converted from an intprimitive to an Integerobject) -
是的，在您的示例中，它将被自动装箱（从int原语转换为Integer对象）-
public static void main(String args[]) {
int a = -1;
passIntToInteger(a); // <-- Auto Boxing
}
private static void passIntToInteger(Integer a) {
System.out.println(a);
}
Java also has (auto-)unboxing (converting from an Integerobject to an intprimitive) -
Java 还具有（自动）拆箱功能（从Integer对象转换为int原语）-
public static void main(String args[]) {
Integer a = -1;
passIntegerToInt(a); // <-- Auto Un-Boxing
}
private static void passIntegerToInt(int a) {
System.out.println(a);
}
This allows you to use primitives with collections, otherwise List<Integer>could not store int(s) (for example).
这允许您将原语与集合一起使用，否则List<Integer>无法存储int（例如）。
回答by FrancescoDS
Yes it is possible to do it, and it is possible to do also the opposite (from Integer to int)
是的，可以这样做，也可以做相反的事情（从整数到整数）
