interface
Ordinary class: only concrete implementation
Abstract class: both concrete implementation and specification (abstract method)
Interface: only specification (abstract method)
The keyword for declaring a class is class, and the keyword for declaring an interface is interface
Code sample:
UserService
package com.oop.demo09;
public interface UserService {
//接口中所有的常量默认是 public abstract final
//接口中的所有定义的方法其实都是抽象的 public abstract(默认有可以不写）
void add(String name);//增
void delete(String name);//删
void update(String name);//改
void query(String name);//查
}
Classes that use imimplements to implement interfaces need to rewrite methods in the
interface. Multiple inheritance can be achieved through interfaces
Code sample:
UserService
package com.oop.demo09;
public interface UserService {
//接口中所有的常量默认是 public abstract final
//接口中的所有定义的方法其实都是抽象的 public abstract(默认有可以不写）
void add(String name);//增
void delete(String name);//删
void update(String name);//改
void query(String name);//查
}
TimeService
package com.oop.demo09;
public interface TimeService {
void Timer();
}
UserServiceImpl
package com.oop.demo09;
//用imimplements实现接口的类需要重写接口中的方法
//接口可以实现多继承
public class UserServiceImpl implements UserService,TimeService{
@Override
public void add(String name) {
}
@Override
public void delete(String name) {
}
@Override
public void update(String name) {
}
@Override
public void query(String name) {
}
@Override
public void Timer() {
}
}
Summary: Through the interface, the classification of projects can be realized, which is conducive to improving work efficiency.
Abstract thinking is the core of java.