面向對象編程(高級)

類變量和類方法

01:

package ChildDemo;public class Child {private String name;public static int cnt = 0;public Child(String name){this.name = name;}public void join(){System.out.println(name +"join the game");} }//=========================================package ChildDemo;public class TestDemo01 {public static void main(String[] args){Child ch1 = new Child("Tom");ch1.join();ch1.cnt++;Child ch2 = new Child("Bom");ch2.join();ch2.cnt++;Child ch3 = new Child("Jack");ch3.join();ch3.cnt++;System.out.println(Child.cnt);} }

什么是類變量和如何定義

01:

package HomeWork07;public class VisitStatic {public static void main(String[] args){System.out.println(A.name);A a = new A();System.out.println("a.name = "+a.name);}}//hspedu //a.name = hspeduclass A {public static String name = "hspedu";}

注意事項和細節討論

類方法基本介紹

01:

package HomeWork07;public class StaticMethod {public static void main(String[] args) {Stu tom = new Stu("tom"); // tom.payFee(100);//OKStu.payFee(100);Stu marry = new Stu("marry");marry.payFee(200);Stu.showFee();} }class Stu{private String name;private static double fee = 0;public Stu(String name) {this.name = name;}public static void payFee(double fee){Stu.fee +=fee;}public static void showFee(){System.out.println("學費有 = "+Stu.fee);}}

類方法經典的使用場景

01:

System.out.println(Math.sqrt(9));//3

02:

class MyTools {public static double calSum(double n1,double n2){return n1+n2;} }

注意事項

• 靜態方法只能訪問靜態成員

[外鏈圖片轉存失敗,源站可能有防盜鏈機制,建議將圖片保存下來直接上傳(img-TM4MzTp8-1634390172741)(C:\Users\Tom\AppData\Roaming\Typora\typora-user-images\image-20210917134451584.png)]

小練習

main方法語法

深入理解main方法

01:

package WorkDemo02323;public class Main01 {private static String name = "hspedu";private int n1 = 100000;public static void hi(){System.out.println("hi");}public void cry(){System.out.println("cry");}public static void main(String[] args){System.out.println("name = "+name);hi();//靜態方法main不可以訪問本類的非靜態成員//System.out.println("n1 = "+n1);//Error//cry();//ErrorMain01 main01 = new Main01();System.out.println(main01.n1);main01.cry();} }

案例演示

01:

package WorkDemo01;public class Main02 {public static void main(String[] args){for (int i = 0;i<args.length;i++){System.out.println(args[i]);}} }

代碼塊

01:

package CodeBlockDemo;public class CodeBlock {public static void main(String[] args){Movie hello_lin = new Movie("hello lin");Movie hello_lin02 = new Movie("hello lin",2131,"DAFS");} }class Movie {private String name;private double price;private String director;{System.out.println("001");System.out.println("002");System.out.println("003");}public Movie(String name) {this.name = name;System.out.println("Movie(String name)");}public Movie(String name, double price) {this.name = name;this.price = price;}public Movie(String name, double price, String director) {this.name = name;this.price = price;this.director = director;System.out.println("Movie (String name,double price,String director)");} }

結果如下:

注意事項和細節討論

01:

public class CodeBlockDemo01 {public static void main(String[] args){//1 situationAA aa = new AA();//static code block} }//class BB //{ // static { // System.out.println("BB static codeblock"); // } //}class AA extends BB {static {System.out.println("static code block");}}

02:

public class CodeBlockDemo01 {public static void main(String[] args){//2 situationAA aa = new AA();// BB static codeblock // static code block} }class BB {static {System.out.println("BB static codeblock");} }class AA extends BB {static {System.out.println("static code block");}}

03:

public class CodeBlockDemo01 {public static void main(String[] args){//3 situationAA aa = new AA();System.out.println(Cat.n1);// BB static codeblock // static code block // Cat static codeblock // 999} }class Cat {public static int n1 = 999;static {System.out.println("Cat static codeblock");} }class BB {static {System.out.println("BB static codeblock");} }class AA extends BB {static {System.out.println("static code block");}}

• static代碼塊，是在類加載時執行的，而且只會執行一次

01:

public class CodeBlockDemo01 {public static void main(String[] args){AA aa = new AA();System.out.println(Cat.n1);System.out.println(Cat.n1);// BB static codeblock // static code block // Cat static codeblock // 999 // 999} }class Cat {public static int n1 = 999;static {System.out.println("Cat static codeblock");} }class BB {static {System.out.println("BB static codeblock");} }class AA extends BB {static {System.out.println("static code block");}}//================================================public class CodeBlockDemo01 {public static void main(String[] args){DD dd = new DD();DD dd1 = new DD();//DD RUSH!!!} }class DD {static {System.out.println("DD RUSH!!!");} }

• 普通的代碼塊，在創建對象實例時，會被隱式的調用，每創建一次，就會調用一次，如果只是使用類的靜態成員，普通代碼塊并不會執行

• 普通代碼塊，在new對象時被調用，而且是每創建一個對象就調用一次，可以簡單的理解為，普通代碼塊是構造器的補充

01：

public class CodeBlockDemo01 {public static void main(String[] args){System.out.println(DD.n1);// DD RUSH!!! // 8888} }class DD {public static int n1 = 8888;static {System.out.println("DD RUSH!!!");}{System.out.println("DD code");} }class Cat {public static int n1 = 999;static {System.out.println("Cat static codeblock");} }class BB {static {System.out.println("BB static codeblock");} }class AA extends BB {static {System.out.println("static code block");}}

01:

package CodeBLockDemo02;public class CodeBlockDetail02 {public static void main(String[] args){A a = new A(); // getN1 // A static 01} }class A {private static int n1 = getN1();static {System.out.println("A static 01");}public static int getN1(){System.out.println("getN1");return 100;} }//============================================package CodeBLockDemo02;public class CodeBlockDetail02 {public static void main(String[] args){A a = new A();// A static 01 // getN1} }class A {static {System.out.println("A static 01");}private static int n1 = getN1();public static int getN1(){System.out.println("getN1");return 100;} }

02:

package CodeBLockDemo02;public class CodeBlockDetail02 {public static void main(String[] args){A a = new A();// A static 01 // getN1 // getN2 // normal codeblock} }class A {private int n2 = getN2();{System.out.println("normal codeblock");}static {System.out.println("A static 01");}private static int n1 = getN1();public static int getN1(){System.out.println("getN1");return 100;}public int getN2(){System.out.println("getN2 ");return 200;} }//=================================================package CodeBLockDemo02;public class CodeBlockDetail02 {public static void main(String[] args){A a = new A();// A static 01 // getN1 // normal codeblock // getN2} }class A {{System.out.println("normal codeblock");}private int n2 = getN2();static {System.out.println("A static 01");}private static int n1 = getN1();public static int getN1(){System.out.println("getN1");return 100;}public int getN2(){System.out.println("getN2 ");return 200;}}

03:

package CodeBLockDemo02;public class CodeBlockDetail02 {public static void main(String[] args){A a = new A();// A static 01 // getN1 // normal codeblock // getN2 // A constructor} }class A {{System.out.println("normal codeblock");}private int n2 = getN2();static {System.out.println("A static 01");}private static int n1 = getN1();public static int getN1(){System.out.println("getN1");return 100;}public int getN2(){System.out.println("getN2 ");return 200;}public A(){System.out.println("A constructor");}}

01:

package CodeBLockDemo02;public class CodeBlockDetail03 {public static void main(String[] args){new BBB();// AAA codeBlock // AAA() 構造器被調用... // BBB的normal codeBlock // BB() 構造器被調用...} }class AAA {{System.out.println("AAA codeBlock");}public AAA(){System.out.println("AAA() 構造器被調用...");} }class BBB extends AAA{{System.out.println("BBB的normal codeBlock");}public BBB(){System.out.println("BB() 構造器被調用...");}}

01:

package CodeBlockDemo003;public class TestWork {public static void main(String[] args){new B02();// getVal01 // A02的一個靜態代碼塊... // getVal03 // B02的一個靜態代碼塊 // A02的第一個普通代碼塊... // getVal02 // A02的構造器 // getVal04 // B02的第一個普通代碼塊... // B02的構造器} }class A02 {private static int n1 = getVal01();static{System.out.println("A02的一個靜態代碼塊...");}{System.out.println("A02的第一個普通代碼塊...");}public int n3 = getVal02();public static int getVal01(){System.out.println("getVal01");return 10;}public int getVal02(){System.out.println("getVal02");return 10;}public A02(){System.out.println("A02的構造器");} }class B02 extends A02{private static int n3 = getVal03();static {System.out.println("B02的一個靜態代碼塊");}public int n5 = getVal04();{System.out.println("B02的第一個普通代碼塊...");}public static int getVal03(){System.out.println("getVal03");return 10;}public int getVal04(){System.out.println("getVal04");return 10;}public B02(){System.out.println("B02的構造器");} }

02:

package CodeBlockDemo003;public class TestDemo0123 {public static void main(String[] args){new C02(); // 200 // 100 // 200} }class C02 {private int n1 =100;private static int n2 = 200;private void m1(){}private static void m2(){}static {//System.out.println(n1);//ErrorSystem.out.println(n2);//ok//m1();//Errorm2();}{System.out.println(n1);System.out.println(n2);//okm1();m2();}}

小練習

01:

package CodeBlockDemo003;public class Person {public static int total;static{total = 100;System.out.println("in static block");}}class Test {public static void main(String[] args){System.out.println("total = "+Person.total);System.out.println("total = "+Person.total);// in static block //total = 100 //total = 100} }

02:

單例設計模式

單利模式-餓漢式

• 1.將構造器私有化

• 2.在類的內部直接創建對象(該對象是static)

• 3.提供一個public的static方法，return 該對象

• 對象，通常是重量級的對象，餓漢式可能造成創建了對象，但是沒有使用

01:

package SingleDemo;public class SingleTon01 {public static void main(String[] args){GirlFriend instance = GirlFriend.getInstance();System.out.println(instance);GirlFriend instance02 = GirlFriend.getInstance();System.out.println(instance02);// GirlFriend{name='xiaoRed'} // GirlFriend{name='xiaoRed'}}}class GirlFriend {private String name;private static GirlFriend gf = new GirlFriend("xiaoRed");private GirlFriend(String name) {this.name = name;}public static GirlFriend getInstance(){return gf;}@Overridepublic String toString() {return "GirlFriend{" +"name='" + name + '\'' +'}';} }

單例模式-懶漢式

• 構造器私有化
• 定義一個static靜態屬性對象
• 提供一個public的static方法，可以return一個Cat對象
• 懶漢式，只有當用戶使用getInstance時，才return Cat對象，后面再次調用時，會返回上次創建的Cat對象,從而保證了單例

01:

package SingleDemo;public class SingleTon02 {public static void main(String[] args){Cat ins = Cat.getInstance();System.out.println(ins);Cat ins2 = Cat.getInstance();System.out.println(ins2);}// Cat constructor // Cat{name='XiaoCute'} // Cat{name='XiaoCute'}}class Cat {private String name;private static Cat cat;private Cat(String name) {System.out.println("Cat constructor");this.name = name;}public static Cat getInstance(){if (cat==null){cat = new Cat("XiaoCute");}return cat;}@Overridepublic String toString() {return "Cat{" +"name='" + name + '\'' +'}';} }

tip:

• 當多個進程同時進入時，有可能會導致創建多個Cat對象(保留最后那個對象)，從而破壞單例

public static Cat getInstance(){if (cat==null){cat = new Cat("XiaoCute");}return cat;}

餓漢式VS懶漢式

小結

final關鍵字

01:

final class C{}

02:

class C{public final void hi(){} }

03:

class E{public final double TAX_RATE = 0.08; }

04:

class F{public void cry(){//這時，NUM 也稱為 局部變量final double NUM = 0.01;} }

final使用注意事項和細節討論

01:

package DemoFinal;public class FinalDetail01 {public static void main(String[] args){} }class AA {public final double TAX_RATE = 0.08;//public final double TAX_RATE01;//Errorpublic final double TAX_RATE02;public final double TAX_RATE03;public AA(){TAX_RATE02 = 0.09;}{TAX_RATE03 = 0.07;} }

02:

public class FinalDetail01 {public static void main(String[] args){} }class BB {public static final double TAX_RATE = 99.9;public static final double TAX_RATE01;//Error static final 不能在構造器賦值 // public static final double TAX_RATE03; // // public BB() // { // TAX_RATE03 = 0.9; // }static {TAX_RATE01 = 0.88;} }

03：

public class FinalDetail01 {public static void main(String[] args){CC c = new CC();} }final class CC{}

04:

public class FinalDetail01 {public static void main(String[] args){new EE().cal();} }class DD{public final void cal(){System.out.println("cal()方法");} }class EE extends DD{}

01:

public class FinalDetail02 {public static void main(String[] args){} }final class AAA {//一般來說，如果一個類已經是final類，就沒有必要再將方法修飾成final方法public final void cry(){System.out.println("cry()");} }

02:

public class FinalDetail02 {public static void main(String[] args){System.out.println(BBB.num);}//10000 }class BBB {public final static int num = 10000;static {System.out.println("codeBlock ing");} }//================================================public class FinalDetail02 {public static void main(String[] args){System.out.println(BBB.num);}//10000 }class BBB {public static final int num = 10000;static {System.out.println("codeBlock ing");} }//=================================================public class FinalDetail02 {public static void main(String[] args){System.out.println(BBB.num);} // codeBlock ing //10000 }class BBB {public static int num = 10000;static {System.out.println("codeBlock ing");} }

final應用實例

01：

public class FinalExercise01 {public static void main(String[] args){Circle circle = new Circle(5.0);System.out.println("area = "+circle.calArea());//area = 78.5} }class Circle {private double radius;private final double PI;// = 3.14;public Circle(double radius) {this.radius = radius;//PI = 3.14;}{PI = 3.14;}public double calArea(){return PI*radius*radius;}}

02:

抽象類

01:

package AbstractDemo01;public class Abstract01 {public static void main(String[] args){} }abstract class Animal {private String name;public Animal(String name){this.name = name;}public abstract void eat();//public abstract void eat(){};//ERROR }

抽象類的介紹

抽象類使用的注意事項和細節討論

01：

package AbstractDemo01;public class AbstractDetail01 {public static void main(String[] args){//A a = new A();//Error} }abstract class A{//public abstract int n1 = 1;//ERROR//抽象類可以沒有抽象方法public void hi(){System.out.println("hi");}}

01:

package AbstractDemo01;public class AbstractDetail02 {public static void main(String[] args){} }abstract class D {public int n1 = 10;public static String name = "dada";public void hi(){System.out.println("j1");}public abstract void hello();public static void ok(){System.out.println("ok");} }

02:

public class AbstractDetail02 {public static void main(String[] args){} }abstract class E {public abstract void hi(); }abstract class F extends E{}class G extends E {@Overridepublic void hi() {} }

小練習

01：

02:

package AbstractDemo0102;public class AbstractExercise01 {public static void main(String[] args){Manager jack = new Manager("jack", 99, 50000);jack.setBonus(8000);jack.work();CommonEmployee tom = new CommonEmployee("tom", 888, 20000);tom.work();}}//===================================================package AbstractDemo0102;abstract public class Employee {private String name;private int age;private double salary;public Employee(String name, int age, double salary) {this.name = name;this.age = age;this.salary = salary;}public abstract void work();public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}public double getSalary() {return salary;}public void setSalary(double salary) {this.salary = salary;} }//===========================================package AbstractDemo0102;public class Manager extends Employee{private double bonus;public Manager(String name, int age, double salary) {super(name, age, salary);}public double getBonus() {return bonus;}public void setBonus(double bonus) {this.bonus = bonus;}@Overridepublic void work() {System.out.println("manager = "+getName());} }//==================================================package AbstractDemo0102;public class CommonEmployee extends Employee{public CommonEmployee(String name,int id,double salary){super(name,id,salary);}@Overridepublic void work() {System.out.println("Common worker = "+getName()+"working...");}}

抽象類最佳實踐-模板設計模式

01：

package AbstractDemo03;public class TestWork01 {public static void main(String [] args){AA aa = new AA();aa.calculatTime();BB bb = new BB();bb.calculatTime();} }//===============================================package AbstractDemo03;abstract public class Template {public abstract void job();public void calculatTime(){long start = System.currentTimeMillis();//單位是msjob();//動態綁定long end = System.currentTimeMillis();System.out.println("time = "+(end-start));} }//=============================================package AbstractDemo03;public class AA extends Template {public void job(){long num = 0;for (long i = 1;i<=1000000000;i++){num+=i;}} }//================================================package AbstractDemo03;public class BB extends Template{public void job(){long num = 0;for (long i = 1;i<=8000000;i++) {num *= i;}} }

接口

快速入門

01:

package InterfackDemo01;public class Interface01 {public static void main(String[] args){Camera camera = new Camera();Phone phone = new Phone();Computer computer = new Computer();computer.work(phone);computer.work(camera);// phone work // phone stop // Camera work // Camera stop} }//===========================================package InterfackDemo01;public class Camera implements UsbInterFace{@Overridepublic void stopWork() {System.out.println("Camera stop");}@Overridepublic void startWork() {System.out.println("Camera work");} }//================================================package InterfackDemo01;public class Computer {public void work(UsbInterFace usbInterFace){usbInterFace.startWork();usbInterFace.stopWork();} }//================================================package InterfackDemo01;public class Phone implements UsbInterFace{@Overridepublic void startWork() {System.out.println("phone work");}@Overridepublic void stopWork() {System.out.println("phone stop");} }//==================================================package InterfackDemo01;public interface UsbInterFace {public void startWork();public void stopWork(); }

基本介紹

01:

package InterfackDemo01;public class Interface02 {public static void main(String[] args){} }class A implements AInterface {public void hi() {System.out.println("hi()...");} }//==================================package InterfackDemo01;public interface AInterface {public int n1 = 10;//在接口中，抽象方法，可以省略abstract關鍵字public void hi();//public abstract void hi();// public void ok() // { // System.out.println("ok....."); // } ERROR,要加default關鍵字default public void ok(){System.out.println("ok....");}public static void cry(){System.out.println("cry....");}}

深入討論

01:

package InterfackDemo01;public class InterFaceDemo {public static void main(String [] args){MysqlDB mysqlDB = new MysqlDB();OracleDB oracleDB = new OracleDB();InterFaceDemo interFaceDemo = new InterFaceDemo();interFaceDemo.t(mysqlDB);interFaceDemo.t(oracleDB);// connect // close // O connect // B close}public void t(DBInterface db){db.connect();db.close();} }//====================================================package InterfackDemo01;public class MysqlDB implements DBInterface{@Overridepublic void connect() {System.out.println("connect");}@Overridepublic void close() {System.out.println("close");} }//====================================================package InterfackDemo01;public class OracleDB implements DBInterface{@Overridepublic void connect() {System.out.println("O connect");}@Overridepublic void close() {System.out.println("B close");} }//======================================================package InterfackDemo01;public interface DBInterface {public void connect();public void close(); }

注意事項和細節

• 接口不能被實例化
• 接口中所有的方法是public方法，接口中抽象方法可以不用abstract修飾
• 一個普通類實現接口，就必須將該接口的所有方法都實現，可以使用alt+enter來解決
• 抽象類實現接口，可以不用實現接口的方法
• 一個類可以同時實現多個接口
• 接口中的屬性，只能是final的，而且是public static final修飾符。比如:int a = 1；實際上是public static final int a = 1;(必須初始化)
• 接口中屬性的訪問形式：接口類.屬性名
• 一個接口不能繼承其他的類，但是可以繼承多個別的接口 interface A extends B,C{}
• 接口的修飾符只能是public或默認，這點和類的修飾符是一樣的

小練習

實現接口VS繼承類

01:

package MonkeyDemo;public class ExtendsVSInterface {public static void main(String[] args){LittleMonkey wukong = new LittleMonkey("wukong");wukong.climbing();wukong.swimming();wukong.frying();} }interface Fishable {void swimming(); }interface Birdable {void frying(); }class Monkey {public String getName() {return name;}public Monkey(String name) {this.name = name;}private String name;public void climbing(){System.out.println("Monkey can climbing");} }class LittleMonkey extends Monkey implements Fishable,Birdable{public LittleMonkey(String name) {super(name);}@Overridepublic void swimming() {System.out.println(getName()+"can swim by learning");}@Overridepublic void frying() {System.out.println(getName()+"can fry by learning");} }

tip:

• 當子類繼承了父類，就自動的擁有父類的功能，如果子類需要擴展功能，可以通過實現接口的方式來擴展，可以理解，實現接口，是對java單繼承機制的一種補充

接口的多態特性

接口的多態體現:

• 接口類型的變量可以指向實現了這個接口的對象實例

繼承體現的多態：

• 父類類型的變量可以指向繼承它的子類的對象實例

01:

package MonkeyDemo;public class InterfacePolyParameter {public static void main(String[] args){IF if01 = new Monster();if01 = new Car();AAA a = new BBB();a = new CCC();} }class AAA{}class BBB extends AAA{}class CCC extends AAA{}interface IF{}class Monster implements IF{} class Car implements IF{}

02:

package MonkeyDemo;public class InterfacePolyArr {public static void main(String[] args){Usb[] usbs = new Usb[2];usbs[0] = new Phone();usbs[1] = new Camera();for (int i = 0;i<usbs.length;i++){usbs[i].work();if (usbs[i] instanceof Phone){((Phone)usbs[i]).call();}}// Phone can work // Phone can call // Camera can work} }interface Usb{void work(); }class Phone implements Usb{public void call(){System.out.println("Phone can call ");}@Overridepublic void work() {System.out.println("Phone can work");} }class Camera implements Usb{@Overridepublic void work() {System.out.println("Camera can work");} }

03：

package MonkeyDemo;public class InterfacePolyPass {public static void main(String[] args){IG ig = new Teacher();IH ih = new Teacher();} }interface IH{} interface IG extends IH{}class Teacher implements IG{}

小練習

內部類

01:

package MonkeyDemo;public class InnerClass {//外部其他類public static void main(String[] args){} }class Outer//外部類 {private int n1 = 100;public Outer(int n1){this.n1 = n1;}public void m1(){System.out.println("m1()");}{System.out.println("codeBlock");}class Inner{//內部類} }

內部類的分類

局部內部類的使用

01:

package LocalInnerClass;public class LocalInnerClass {public static void main(String[] args){}}class Outer02 {private int n1 = 100;public void m1(){class Inner02{public void f1(){System.out.println("n1 = "+n1);}}}class Inner03 extends Inner02{} }

02:

public class LocalInnerClass {public static void main(String[] args){}}class Outer02 {private int n1 = 100;public void m1(){//public class Inner02//errorfinal class Inner02//無法被繼承{public void f1(){System.out.println("n1 = "+n1);}}} }

03:

package LocalInnerClass;public class LocalInnerClass {public static void main(String[] args){Outer02 outer02 = new Outer02();outer02.m1();System.out.println("outer02的hashcode = "+outer02);}// n1 = 800 Outer n1 = 100 // Outer02.this hashcode = LocalInnerClass.Outer02@5fd0d5ae // Outer02 m2() // outer02的hashcode = LocalInnerClass.Outer02@5fd0d5ae}class Outer02 {private int n1 = 100;public void m2(){System.out.println("Outer02 m2()");}public void m1(){final class Inner02{private int n1 = 800;public void f1(){System.out.println("n1 = "+n1+" Outer n1 = "+Outer02.this.n1);System.out.println("Outer02.this hashcode = "+Outer02.this);m2();}}Inner02 inner02 = new Inner02();inner02.f1();}}

匿名內部類本質

01:

package AnnoymousInnerClass;public class AnonymousInnerClass {public static void main(String[] args){ // Cat cat = new Cat(); // cat.cry();AAA cat = new AAA() {@Overridepublic void cry() {System.out.println("cry()...");}};cat.cry();System.out.println(cat.getClass());// cry()... // class AnnoymousInnerClass.AnonymousInnerClass$1} }interface AAA {public void cry(); }class Cat implements AAA{public void cry(){System.out.println("cry。。。");} }

02:

package AnnoymousInnerClass;public class InnerWorkDemo {public static void main(String[] args){Father father = new Father("jack"){@Overridepublic void work() {System.out.println("work");}};father.work();System.out.println(father.getClass());// work // class AnnoymousInnerClass.InnerWorkDemo$1} }class Father {public Father(String name){}public void work(){} }//======================================================package AnnoymousInnerClass;public class InnerWorkDemo {public static void main(String[] args){Father father = new Father("jack");father.work();System.out.println(father.getClass()); // class AnnoymousInnerClass.Father} }class Father {public Father(String name){}public void work(){} }//===================================================package AnnoymousInnerClass;public class InnerWorkDemo {public static void main(String[] args){Animal animal = new Animal(){@Overridevoid eat() {System.out.println("animal eat");}};animal.eat();//animal eat} }abstract class Animal {abstract void eat(); }

匿名內部類的使用

01：

package AnnoymousInnerClass;public class AnonymousInnerClassDetail {public static void main(String[] args){Outer05 outer05 = new Outer05();outer05.f1();//hi()....} }class Outer05 {private int n1 = 99;public void f1(){Person person = new Person(){@Overridepublic void hi() {System.out.println("hi()....");}};person.hi();//動態綁定了，運行類型是Outer05$1} }class Person {public void hi(){System.out.println("Person hi()");} }//==================================================package AnnoymousInnerClass;public class AnonymousInnerClassDetail {public static void main(String[] args){Outer05 outer05 = new Outer05();outer05.f1();//hi()....} }class Outer05 {private int n1 = 99;public void f1(){//class 匿名內部類 extends Person{}new Person(){@Overridepublic void hi() {System.out.println("hi()....");}@Overridepublic void ok(String str) {super.ok(str);}}.ok("jack");} }class Person {public void hi(){System.out.println("Person hi()");}public void ok(String str){System.out.println("Person ok()"+str);} }

02:

package AnnoymousInnerClass;public class AnonymousInnerClassDetail {public static void main(String[] args){Outer05 outer05 = new Outer05();outer05.f1();//hi()....System.out.println("hashcode = "+outer05);// hi()....10 // Outer 99 // Outer05 hashcode = AnnoymousInnerClass.Outer05@6d03e736 // hashcode = AnnoymousInnerClass.Outer05@6d03e736} }class Outer05 {private int n1 = 99;public void f1(){//class 匿名內部類 extends Person{}Person p = new Person(){private int n1 = 10;@Overridepublic void hi() {System.out.println("hi()...."+n1);System.out.println("Outer "+Outer05.this.n1);//Outer05.this就是調用f1的對象System.out.println("Outer05 hashcode = "+Outer05.this);}// @Override // public void ok(String str) { // super.ok(str); // }};p.hi();} }class Person {public void hi(){System.out.println("Person hi()");}public void ok(String str){System.out.println("Person ok()"+str);} }

匿名內部類的最佳實踐

01:

package AnnoymousInnerClass;public class InnerClassWork01 {public static void main(String[] args){//當做實參直接傳遞，簡潔高效f1(new IA() {@Overridepublic void show() {System.out.println("this is famous picture");}});//傳統方式f1(new Car());// this is famous picture // this is famous picture!}public static void f1(IA ia){ia.show();} }interface IA {void show(); }class Car implements IA{@Overridepublic void show() {System.out.println("this is famous picture!");} }

02:

package AnnoymousInnerClass;public class ADemo01 {public static void main(String [] args){CellPhone cellPhone = new CellPhone();cellPhone.alarmclock(new Bell() {@Overridepublic void ring() {System.out.println("lazy pig has got up");}});cellPhone.alarmclock(new Bell() {@Overridepublic void ring() {System.out.println("partner has haven a class");}});} }interface Bell {void ring(); }class CellPhone {public void alarmclock(Bell bell){bell.ring();} }

成員內部類的使用

01：

package AnnoymousInnerClass;public class MemberInnerClass {public static void main(String[] args){Outer08 outer08 = new Outer08();outer08.t1();} }class Outer08 {private int n1 = 10;public String name = "zhan3";class Inner08{public void say(){System.out.println("n1 = "+n1+" name = "+name);}}public void t1(){Inner08 inner08 = new Inner08();inner08.say();} }//===================================================package AnnoymousInnerClass;public class MemberInnerClass {public static void main(String[] args){Outer08 outer08 = new Outer08();outer08.t1();} }class Outer08 {private int n1 = 10;public String name = "zhan3";//example:protected class Inner08{public void say(){System.out.println("n1 = "+n1+" name = "+name);}}public void t1(){Inner08 inner08 = new Inner08();inner08.say();} }

02:

package AnnoymousInnerClass;public class MemberInnerClass {public static void main(String[] args){Outer08 outer08 = new Outer08();outer08.t1();//外部其他類，使用成員內部類的三種方式//1.Outer08.Inner08 inner08 = outer08.new Inner08();//2.Outer08.Inner08 inner08Instance = outer08.getInner08Instance();//3.Outer08.Inner08 inner081 = new Outer08().new Inner08();} }class Outer08 {private int n1 = 10;public String name = "zhan3";private void hi(){System.out.println("hi()方法...");}public class Inner08{private int n3 = 20;public void say(){System.out.println("n1 = "+n1+" name = "+name);hi();}}public void t1(){Inner08 inner08 = new Inner08();inner08.say();int a = inner08.n3;System.out.println(a);}public Inner08 getInner08Instance(){return new Inner08();} }

靜態內部類的使用

01:

package StaticInnerClass01;public class StaticInnerClass01 {public static void main(String[] args){} }class Outer10 {private int n1 = 10;private static String name = "zhan3";static class Inner10{public void say(){//System.out.println(n1);//Error static class 無法訪問 非靜態變量System.out.println(name);}} }

02:

package StaticInnerClass01;public class StaticInnerClass01 {public static void main(String[] args){} }class Outer10 {private int n1 = 10;private static String name = "zhan3";private static class Inner10{public void say(){System.out.println(name);}} }

03:

package StaticInnerClass01;public class StaticInnerClass01 {public static void main(String[] args){Outer10 outer10 = new Outer10();outer10.m1();} }class Outer10 {private int n1 = 10;private static String name = "zhan3";static class Inner10{public void say(){System.out.println(name);}}public void m1(){Inner10 inner10 = new Inner10();inner10.say();}}

04：

package StaticInnerClass01;public class StaticInnerClass01 {public static void main(String[] args){Outer10 outer10 = new Outer10();outer10.m1();//外部其他類 使用靜態內部類//1.Outer10.Inner10 inner10 = new Outer10.Inner10();inner10.say();//2.Outer10.Inner10 instance = outer10.getInstance();} }class Outer10 {private int n1 = 10;private static String name = "zhan3";static class Inner10{public void say(){System.out.println(name);}}public void m1(){Inner10 inner10 = new Inner10();inner10.say();}public Inner10 getInstance(){return new Inner10();}}

小練習

輸出結果:

5

5

總結

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