番禺区网站建设,网站建设与管理教学设计,国防教育网站建设说明书,中国建盏大师排名2021lesson Thirteen 2018-05-10 02:10:43final:最终的#xff0c;可以修饰类、属性、方法1.final修饰类#xff1a;这个类就不能被继承#xff0c;如#xff1a;String类#xff0c;StringBuffer类#xff0c;System类1…lesson Thirteen 2018-05-10 02:10:43final:最终的可以修饰类、属性、方法1.final修饰类这个类就不能被继承如String类StringBuffer类System类1 class SubString extends String{2 //The type SubString cannot subclass the final class String3 }4 final class A{56 }7 class B extends A{8 //The type B cannot subclass the final class A9 }2.final修饰方法不能被重写 如object的getclass();方法(获取当前对象的类名)1 class C{2 public final void f() {3 System.err.println(被final修饰的方法1);4 }5 }6 class D extends C{7 public void f() {8 System.err.println(被final修饰的方法2);9 //Cannot override the final method from C10 }11 }3.final修饰属性此属性就是一个常量习惯常量用全大写表示3.1此常量不能默认初始化3.2可以显式赋值、代码块、构造器1 class E{2 final int INT 123;34 public void e() {5 System.err.println(INT);6 INT 12;7 //The final field E.INT cannot be assigned8 }9 }abstract:抽象的可以修饰类、方法 即抽象类抽象方法 不能修饰属性、构造器、private、final、static1.1抽象类1.1.1不可以被实例化1.1.2抽象类有构造器(凡是类都有构造器)1.1.3抽象方法所在的类一定是抽象类1.1.4抽象类中可以没有抽象方法1 abstract class eemployeee{2 private String name;3 private int id;4 private double salary;5 public String getName() {6 return this.name;7 }8 public void setName(String name) {9 this.name name;10 }11 public int getId() {12 return this.id;13 }14 public void setId(int id) {15 this.id id;16 }17 public double getSalary() {18 return this.salary;19 }20 public void setSalary(double salary) {21 this.salary salary;22 }2324 public abstract void work();25 //这就是抽象方法也可以没有26 }1.2抽象方法1.2.1格式没有方法体包括{}。 如public abstract void work();1.2.2抽象方法只保留方法的功能而具体的执行交给继承抽象类的子类由子类重写此抽象方法1.2.3若子类继承抽象类并重写了所以的抽象方法则可以实例化反之则不能1 class Manager extends eemployeee{2 private double bonus;3 public double getBonus() {4 return this.bonus;5 }6 public void setBonus(double bonus) {7 this.bonus bonus;8 }9 public void work(){10 System.out.println(监督工作);1112 }13 }1415 class CommonEmployee extends eemployeee{16 public void work(){17 System.out.println(工人在流水线工作);1819 }20 }interface:接口,与类并行的概念interface(接口)是与类并行的概念1.接口可是看作是一个特殊的抽象类是常量与抽象方法的集合。不能包含变量和一般的方法2.接口是没有构造器的3.接口定义的就是一种功能可以被类实现(implements)如class DD extends CC implements A1 interface A {2 //常量所有的常量都用 public static final3 int j 1;4 public static final int i 0;5 //抽象方法所有的都用 public abstract修饰6 void method1();7 public abstract void method2();8 }4.实现接口的类必须重写其中所有的抽象方法方可实例化不然此类仍为抽象类1 interface A {2 //常量所有的常量都用 public static final3 int j 1;4 public static final int i 0;5 //抽象方法所有的都用 public abstract修饰6 void method1();7 public abstract void method2();8 }9101112 abstract class BB implements A {1314 }5.类可以实现多个接口-----JAVA中的类是单继承的1 class CC extends DD implements A,B {2 public void method1(){34 }5 public void method2(){67 }8 public void method3(){910 }11 }6.接口与接口之间是继承关系而且可以多继承1 interface A {2 //常量所有的常量都用 public static final3 int j 1;4 public static final int i 0;5 //抽象方法所有的都用 public abstract修饰6 void method1();7 public abstract void method2();8 }9 interface B{10 public abstract void method3();11 }12 interface C extends B,A{13 public abstract void method4();14 }1 interface Runner{2 public void Strat();3 abstract void Run();4 public abstract void Stop();56 }78 class Person implements Runner{910 Override11 public void Strat() {12 System.out.println(人在走路);13 }1415 Override16 public void Run() {17 System.out.println(人在跑);18 }1920 Override21 public void Stop() {22 System.out.println(人在休息);23 }2425 public void Dance() {26 System.out.println(人在跳舞);27 }2829 }30 class Car implements Runner{3132 Override33 public void Strat() {34 System.out.println(汽车启动);35 }3637 Override38 public void Run() {39 System.out.println(汽车在行驶);40 }4142 Override43 public void Stop() {44 System.out.println(汽车停了);45 }4647 public void fillFuel(){48 System.out.println(汽车在加油);49 }50 public void crack() {51 System.out.println(撞车了);52 }5354 }55 class Bird implements Runner{5657 Override58 public void Strat() {59 System.out.println(鸟在起飞);60 }6162 Override63 public void Run() {64 System.out.println(鸟在跑);65 }6667 Override68 public void Stop() {69 System.out.println(鸟停下了);70 }7172 public void fly() {73 System.out.println( 鸟在飞 );74 }7576 }interface的练习1 public static void main(String[] args) {23 interfaceTest1 i new interfaceTest1();4 Fly duck new Duck();5 i.test3(duck);67 new interfaceTest1().test1(new Duck());8 new interfaceTest1().test2(new Duck());9 new interfaceTest1().test3(new Duck());10 new interfaceTest1().test4(new Duck(), new Duck(), new Duck());11 }1213 public void test1(Run duck){14 duck.run();15 // duck.fly();16 // duck.swim();17 }18 public void test2(Swim duck){19 // duck.fly();20 duck.swim();21 // duck.run();22 }23 public void test3(Fly duck){24 // duck.run();25 // duck.swim();26 duck.fly();27 }28 public void test4(Run r, Swim s, Fly f){29 r.run();30 s.swim();31 f.fly();32 }3334353637383940 interface Run{41 void run();42 }43 interface Swim{44 void swim();45 }46 interface Fly{47 void fly();48 }4950 class Duck implements Run,Swim,Fly{5152 Override53 public void fly() {54 System.out.println(flying);55 }5657 Override58 public void swim() {59 System.out.println(swimming);60 }6162 Override63 public void run() {64 System.out.println(running);65 }6667 }interface多态的运用11 public static void main(String[] args) {2 Computer computer new Computer();3 computer.work(new Flash());4 Printer p new Printer();5 computer.work(p);678 USB phone new USB(){910 Override11 public void start() {12 // TODO Auto-generated method stub13 System.out.println(start working);14 }1516 Override17 public void stop() {18 System.out.println(stop working);19 }2021 };222324 }25262728293031 interface USB{32 public static final int i 10;33 public abstract void start();34 public abstract void stop();35 }3637 class Flash implements USB {3839 Override40 public void start() {41 System.out.println(闪存开始工作);42 }4344 Override45 public void stop() {46 System.out.println(闪存停止工作);47 }4849 }5051 class Printer implements USB{5253 Override54 public void start() {55 System.out.println(打印机开始工作);56 }5758 Override59 public void stop() {60 System.out.println(打印机停止工作);61 }6263 }interface多态的运用2如您对本文有疑问或者有任何想说的请点击进行留言回复万千网友为您解惑
