为什么我写java程序时，明明一点语法错误都没有，但是编译时总会出这个错误：non-static variable this cannot be referenced from a static context？ 害得我要在每一个变量、函数、类前加上static才能解决，为什么会这样呢？有没有什么好的解决方法？

Nested classes are classes that are declared as members of other classes or scopes. Nesting classes is one way to better organize your code. For example, say you have a non-nested class (also known as ...