Java Annotations
Java 的 annotation
- 以@开头 比如@Override.
- 不改变complied program的action
- annotation不完全是comments 能够改变一段代码compile的方式
下面这段代码因为base class里没有display(int x), 所以是用@Override就会报错。
/* Java program to demonstrate that annotations are not barely comments (This program throws compiler error because we have mentioned override, but not overridden, we haver overloaded display) */ class Base { public void display() { System.out.println("Base display()"); } } class Derived extends Base { @Override public void display(int x) { System.out.println("Derived display(int )"); } public static void main(String args[]) { Derived obj = new Derived(); obj.display(); } }