声明变量的主方法和内部主方法有什么区别？ [英] what is difference between declaring variable out of main method and inside main method?

问题描述

当我阅读有关Java的书时，我看到了一个这样写的例子。我想知道我可以在main方法之外声明变量吗？声明变量外部和内部主方法有什么区别？什么是静态在这里的作用？请有人向我解释一下？我是java的新手。

When I was reading book about Java , I saw one example written like this. And I am wondering can I declare variable in outside of main method ? What is difference between declaring variable outside and inside main method? what is " static" 's role in here ? Please some one explain to me? I am new in java.

public class Printstuff {
      static int an_integer = 0;
        public static void main(String[] args) {
          int an_integer = 2;
          String[] some_strings = {"Shoes", "Suit", "Tie" };
          an_integer = an_integer - 1;
          some_strings[an_integer] = some_strings[an_integer] +"+++";
          for (int i = 0; i < some_strings.length; i++)
            System.out.println(some_strings[Printstuff.an_integer]);
        }
    }

祝你好运。

推荐答案

1）内部与外部：

如果声明对象里面一个方法，它只在这个方法中可见。基本上，如果你在它周围放置括号，它只能在这些括号内可见/可访问。

If you declare your object inside a method, it will be visible only in this method. Basically, if you put brackets around it, it's only visible/accessible from within these brackets.

如果你声明你的对象在之外的方法（在课堂内），它取决于 访问修饰符 。

默认情况下，它在该类和整个包中可见/可访问。

If you declare your object outside the method (inside the class), it depends on the access modifier.
By default, it's visible/accessible from within that class and the whole package.

2）静态

静态意味着此对象/变量属于类本身，而不属于其对象。

Static means, that this Object/Variable belongs to the class itself, and not to its objects.

示例：

public class Members {

  static int memberCount;

  public Members() {
     memberCount++;
  }
}

memberCount 只存在一次，无论该类存在多少个对象。 （甚至在创建任何对象之前！）

memberCount exists only once, no matter how many Objects of the class exists. (even before any object is created!)

每次创建成员的新对象时， memberCount 增加了。现在您可以这样访问它： Members.memberCount

Every time you create a new Object of Members, memberCount is increased. Now you can access it like this: Members.memberCount

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