“无法从静态上下文引用非静态方法"背后的原因是什么?

What is the reason behind quot;non-static method cannot be referenced from a static contextquot;?(“无法从静态上下文引用非静态方法背后的原因是什么?)

问题描述

非常常见的初学者错误是当您尝试静态"使用类属性时.没有创建该类的实例.它会给您留下上述错误消息:

The very common beginner mistake is when you try to use a class property "statically" without making an instance of that class. It leaves you with the mentioned error message:

您可以将非静态方法设为静态或将该类的实例设为使用其属性.

You can either make the non static method static or make an instance of that class to use its properties.

这背后的原因是什么?我关心的不是解决方案，而是原因.

private java.util.List<String> someMethod(){
    /* Some Code */
    return someList;            
}

public static void main(String[] strArgs){          
     // The following statement causes the error. 
    java.util.List<String> someList = someMethod();         
}

推荐答案

你不能调用不存在的东西.由于您尚未创建对象，因此非静态方法尚不存在.静态方法(根据定义)始终存在.

You can't call something that doesn't exist. Since you haven't created an object, the non-static method doesn't exist yet. A static method (by definition) always exists.

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