This
- this represents the instantiated object of the current class.
- This calls the attribute in this class. If there is no such attribute in this class, it will continue to search from the parent class.
- This calls the method in this class. If there is no such method in this class, it will continue to search from the parent class.
- This can call the constructor in this class.
static***
Convenient to call (method/variable) without creating an object
- In static methods
不能访问非静态成员方法和非静态成员变量, but in non-static member methods, static member methods/variables can be accessed - Static variables are also called static variables,
当且仅当在类初次加载时会被初始化,可以被修改 - static code block: only in
类加载的时候执行一次 - As long as the loaded class first executes the static code block, and then executes the constructor, no matter the order.
Final: Final
- Use final to modify attributes to represent constants, which can be assigned directly or in the construction method, but
只能被赋值一次 - Using the final modification method means that the method cannot be overridden, but it can be inherited. (Except those with a private modifier)
- Use final to modify the class, which means that the class cannot be inherited.
- Use final in the method parameter, and the parameter value cannot be modified inside the method.
Super
- super represents a reference to the parent object.
- super can call the properties and methods and construction methods of the parent class.