构造函数是静态的或非静态的 [英] Constructor is static or non static

问题描述

根据标准书构造函数是一种特殊类型的函数，用于初始化对象。构造函数被定义为函数，而类函数内部只能有两种类型的静态或非静态。我怀疑构造函数是什么？

As per standard book constructor is a special type of function which is used to initialize objects.As constructor is defined as a function and inside class function can have only two type either static or non static.My doubt is what constructor is ?

1.)As constructor is called without object so it must be static

  Test test =new  Test();//Test() is being called without object
   so must be static

我的疑问是，如果构造函数是静态方法，那么我们如何经常在
构造函数中使用它

My doubt is if constructor is static method then how can we frequently used this inside constructor

Test(){
System.out.println(this);
}

将给出测试@ 12aw212意味着这必须是非静态的...详细说明

Will give Test@12aw212 means this must be non static..Kindly elaborate

推荐答案

你的第二个例子击中了现场。 这个引用在构造函数中可用，这意味着构造函数是针对某个对象执行的 - 当前正在创建的对象。

Your second example hits the spot. this reference is available in the constructor, which means constructor is executed against some object - the one that is currently being created.

原则上，当您创建一个新对象（通过使用 new 运算符）时，JVM将为其分配一些内存，然后在该新创建的对象上调用构造函数。此外，JVM确保在构造函数之前没有调用其他方法（这就是它的特殊之处）。

In principle when you create a new object (by using new operator), JVM will allocate some memory for it and then call a constructor on that newly created object. Also JVM makes sure that no other method is called before the constructor (that's what makes it special).

实际上，在机器级别上，构造函数是一个特殊的函数，隐式此参数。此特殊参数（由运行时传递）使对象和静态方法之间存在差异。换句话说：

Actually, on machine level, constructor is a function with one special, implicit this parameter. This special parameter (passed by the runtime) makes the difference between object and static methods. In other words:

foo.bar(42);

被翻译为：

bar(foo, 42);

其中第一个参数名为 this 。另一方面， static 方法按原样调用：

where first parameter is named this. On the other hand static methods are called as-is:

Foo.bar(42);

转换为：

bar(42);

Foo 这里只是一个现存的命名空间在源代码中。

Foo here is just a namespace existing barely in the source code.

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