静态方法总是加载到内存中吗？ [英] Are static methods always loaded into memory?

问题描述

假设我有一个带有一些Utils类的Java项目，并且那些类只有 static 方法和成员。

Say that I have a Java project with some "Utils" classes, and that those classes have only static methods and members.

运行我的应用程序后，这些方法和成员是否会自动加载到内存中？或者只有在我按照代码调用类时才会发生这种情况？

Once I run my application, are those methods and members automatically loaded into memory? Or that only happens once I call the class along the code?

编辑：一些示例代码来说明我的问题。

Some sample code to illustrate my question.

RandomUtils.java

public class RandomUtils {

    private static Random rand = new Random();

    public static int randInt(int min, int max) {
        // nextInt is normally exclusive of the top value,
        // so add 1 to make it inclusive
        return rand.nextInt((max - min) + 1) + min;
    }
}

MainClass.java

public class MainClass {
        public static void main(String[] args) {
            // Some other operations. Is my class already loaded here?

            int randomNumber = RandomUtils.randInt(1,10); // Or is it only loaded here?
        }
}

如果该类有其他静态成员和方法怎么办？ ，如果它只在我调用其中一个时加载，其他方法也被加载？

And what if that class have other static members and methods, and if it loads only once I call one of them, the other methods are loaded as well?

推荐答案

静态方法（和非静态方法和静态/成员变量）不直接加载到内存中：声明类完整地加载到内存中，包括所有声明的方法和字段。因此，加载静态/非静态方法/字段的方式没有区别。

Static methods (and non-static methods, and static/member variables) are not loaded into memory directly: the declaring class is loaded into memory in its entirety, including all declared methods and fields. As such, there is no difference in the way that static/non-static methods/fields are loaded.

类只在第一次被类加载器加载时由其他代码引用。这构成了按需初始化习惯用语的基础。

A class is only loaded by a class loader the first time it is referenced by other code. This forms the basis of the Initialization on demand idiom.

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