Java chapter6 接口，正则表达式，内部类

6.1接口
例，排序算法需要类实现比较接口。

public interface Comparable{int compareTo(Object other);}

泛型

public interface Comparable<T>
{int compareTo(T other);//parameter has type T
}

例Employee类实现接口
int compareTo(Employee other);
接口里的方法默认是Public的。
注意接口是没有实例的。
定义：
class Employee implements Comparable

public int compareTo(Object otherObject){Employee other=(Employee)otherObject;return Double.compare(salary,other.salary);
}

或

class Employee implements Comparable<Employee>{public int compareTo(Employee other){return Double.compare(salary,other.salary);}
}