The role of interfaces: 1. Interfaces can separate projects, and all layers are developed towards interfaces, improving development efficiency; 2. Interfaces reduce the coupling between code and code; 3. Interfaces can be implemented in multiple ways, Multiple inheritance, and in addition to interfaces, a class can also inherit other classes.
The role of the interface:
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1. Projects can be separated, and all layers are developed for interfaces to improve development efficiency;
2. The interface reduces the coupling between code and code, becomes pluggable, and can be switched at will;
3. Both interfaces and abstract classes can complete a certain function. Interfaces are preferred because interfaces can be implemented and inherited in multiple ways, and in addition to interfaces, a class can also inherit other classes.
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Code sample:
public interface CustomerService { //定義一個推出系統(tǒng)的方法
void logout();
}
package date818;//接口實現(xiàn)類1public class CustomerServierImpl implements CustomerService {
public void logout(){
System.out.println("成功退出系統(tǒng)");
}
}
package date818;//接口實現(xiàn)類2public class CustomerServiceImpl2 implements CustomerService{
public void logout(){
System.out.println("hello world");
}
}
package date818;public class TestCustomer {
public static void main(String[] args){ //需要執(zhí)行CustomerServiceImpl和CustomerImpl2接口實現(xiàn)類中的logout方法
//以下程序面向接口調(diào)用
CustomerService cs = new CustomerServierImpl();//多態(tài)。父類型引用指向子類型對象
//調(diào)用
cs.logout();
CustomerService cs2 = new CustomerServiceImpl2();
cs2.logout();
}
}Define interface
package date818;
public interface Engine { //所有發(fā)動機都可以通過這個接口啟動
void start();
}//定義實現(xiàn)接口的類
package date818;
public class Honda implements Engine{
public void start(){
System.out.println("本田啟動");
}
}
package date818;public class Ymaha implements Engine{
public void start(){
System.out.println("雅馬哈啟動");
}
}//定義生產(chǎn)汽車的類package date818;public class Car { //面向接口編程，不能將類實例化
/**
* 引用接口定義一個屬性e，相當于
* String name;
* Integer age;
* 類里定義的變量是成員變量；方法里定義的變量是局部變量。
*/
Engine e ;//成員變量e
Car(Engine e){ //定義構(gòu)造方法，把局部變量e賦值給成員變量
this.e=e;
} //對外提供的測試方法
public void testEngine(){ //成員變量e
e.start();
}
}//定義測試類package date818;public class TestCar {
public static void main(String[] args){ //生產(chǎn)引擎
Engine e = new Ymaha(); //根據(jù)構(gòu)造方法傳入?yún)?shù)生產(chǎn)汽車
Car c = new Car(e); //測試引擎
c.testEngine();
c.e = new Honda();//已經(jīng)定義了一個實例，直接對實例的參數(shù)修改即可
c.testEngine();
}
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