1. 第一题

    package net.mindview.polymorphism;
    //基类-自行车
    class Cycle{ } //子类-单轮车
    class Unicycle extends Cycle{ } //子类-双轮车
    class Bicycle extends Cycle{ } //子类-三轮车
    class Tricycle extends Cycle{ } public class CycleCompetition {
    public static void ride(Cycle cycle){ } public static void main(String[] args) {
    Bicycle b = new Bicycle();
    ride(b);
    }
    } 你
  2. (略)
  3. (略)
  4. 第四题
    package net.mindview.polymorphism;
    
    import java.util.Random;
    
    //形状
    class Shape{
    public void draw(){}
    public void erase(){}
    } //圆形
    class Cycle1 extends Shape { @Override
    public void draw() {
    System.out.println("draw cycle");
    } @Override
    public void erase() {
    System.out.println("erase cycle");
    } } class Square extends Shape {
    @Override
    public void draw() {
    System.out.println("draw Square");
    } @Override
    public void erase() {
    System.out.println("draw Square");
    }
    } //矩形
    class Triangle extends Shape {
    @Override
    public void draw() {
    System.out.println("draw Triangle");
    } @Override
    public void erase() {
    System.out.println("draw Triangle");
    }
    } //梯形
    class Trapezoid extends Shape {
    @Override
    public void draw() {
    System.out.println("draw Trapezoid");
    } @Override
    public void erase() {
    System.out.println("draw Trapezoid");
    }
    } class RandomShapeFactory {
    Random random = new Random(); //下面画什么形状呢
    public Shape next(){
    switch(random.nextInt()) {
    default:
    case : return new Cycle1();
    case : return new Square();
    case : return new Triangle();
    case : return new Trapezoid();
    }
    }
    } public class Shapes {
    public static void main(String[] args) {
    Shape[] shape = new Shape[];
    RandomShapeFactory factory = new RandomShapeFactory();
    for(int i=; i<shape.length; i++){
    shape[i] = factory.next();
    shape[i].draw();
    } } }
  5. 第五题
    package net.mindview.polymorphism;
    //基类-自行车
    class Cycle{
    public int wheels(){
    return ;
    }
    } //子类-单轮车
    class Unicycle extends Cycle{
    public int wheels(){
    return ;
    }
    } //子类-双轮车
    class Bicycle extends Cycle{
    public int wheels(){
    return ;
    }
    } //子类-三轮车
    class Tricycle extends Cycle{
    public int wheels(){
    return ;
    }
    } public class CycleCompetition {
    public static void ride(Cycle cycle){
    System.out.println(cycle.wheels());
    } public static void main(String[] args) {
    Bicycle b = new Bicycle();
    ride(b);
    }
    }
  6. 第六题
    package net.mindview.polymorphism.Music3;
    
    import net.mindview.polymorphism.Note;
    
    class Instrument {
    public void play(Note i){
    System.out.println("Instrument.play() ");
    } public String toString () {
    return Instrument.class.getName();
    } void adjust(){System.out.println("adjust Instrument");} } class Wind extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Wind.play() ");
    } String what (){ return "Wind"; } void adjust(){System.out.println("adjust Wind");}
    } class Stringed extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Stringed.play() ");
    } String what (){ return "Stringed"; } void adjust(){System.out.println("adjust Stringed");}
    } class Brass extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Brass.play() ");
    } String what (){ return "Brass"; } void adjust(){System.out.println("adjust Brass");}
    } public class Music3 {
    //曲调
    public static void tune(Instrument i){
    i.play(Note.MIDDLE_C);
    } public static void tuneAll(Instrument[] i){
    for(Instrument ins: i){
    tune(ins);
    }
    } public static void main(String[] args) {
    Instrument[] i = {
    new Wind(),
    new Stringed(),
    new Brass()
    };
    tuneAll(i); Instrument t = new Instrument();
    System.out.println(t);
    } }
  7. 第七题
    package net.mindview.polymorphism.Music3;
    
    import net.mindview.polymorphism.Note;
    
    class Instrument {
    public void play(Note i){
    System.out.println("Instrument.play() ");
    } public String toString () {
    return Instrument.class.getName();
    } void adjust(){System.out.println("adjust Instrument");} } class Wind extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Wind.play() ");
    } String what (){ return "Wind"; } void adjust(){System.out.println("adjust Wind");}
    } class Stringed extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Stringed.play() ");
    } String what (){ return "Stringed"; } void adjust(){System.out.println("adjust Stringed");}
    } class Brass extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Brass.play() ");
    } String what (){ return "Brass"; } void adjust(){System.out.println("adjust Brass");}
    } class Other extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Other.play() ");
    } String what (){ return "Other"; } void adjust(){System.out.println("adjust Other");}
    } public class Music3 {
    //曲调
    public static void tune(Instrument i){
    i.play(Note.MIDDLE_C);
    } public static void tuneAll(Instrument[] i){
    for(Instrument ins: i){
    tune(ins);
    }
    } public static void main(String[] args) {
    Instrument[] i = {
    new Wind(),
    new Stringed(),
    new Brass(),
    new Other()
    };
    tuneAll(i); Instrument t = new Instrument();
    System.out.println(t);
    } }
  8. 第八题
    package net.mindview.polymorphism.Music3;
    
    import java.util.Random;
    
    import net.mindview.polymorphism.Note;
    
    class Instrument {
    public void play(Note i){
    System.out.println("Instrument.play() ");
    } public String toString () {
    return Instrument.class.getName();
    } void adjust(){System.out.println("adjust Instrument");} } class Wind extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Wind.play() ");
    } String what (){ return "Wind"; } void adjust(){System.out.println("adjust Wind");}
    } class Stringed extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Stringed.play() ");
    } String what (){ return "Stringed"; } void adjust(){System.out.println("adjust Stringed");}
    } class Brass extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Brass.play() ");
    } String what (){ return "Brass"; } void adjust(){System.out.println("adjust Brass");}
    } class Other extends Instrument {
    @Override
    public void play(Note i) {
    System.out.println("Other.play() ");
    } String what (){ return "Other"; } void adjust(){System.out.println("adjust Other");}
    } class RandomInstrumentFactory {
    Random rand = new Random();
    public Instrument next(){
    switch(rand.nextInt()){
    default:
    case : return new Wind();
    case : return new Stringed();
    case : return new Brass();
    case : return new Other();
    }
    }
    } public class Music3 {
    //曲调
    public static void tune(Instrument i){
    i.play(Note.MIDDLE_C);
    } public static void tuneAll(Instrument[] i){
    for(Instrument ins: i){
    tune(ins);
    }
    } public static void main(String[] args) {
    RandomInstrumentFactory factory = new RandomInstrumentFactory();
    Instrument[] instruments = new Instrument[];
    for(int i=; i<instruments.length; i++){
    instruments[i] = factory.next();
    }
    tuneAll(instruments); Instrument t = new Instrument();
    System.out.println(t);
    } }
  9. 第九题
    package net.mindview.polymorphism;
    
    //啮(nie四声)齿动物
    class Rodent{
    void say(){System.out.println("hi,我是 Rodent");}
    } //老鼠
    class Mouse extends Rodent{
    void say(){System.out.println("hi,我是 Mouse");}
    } //鼹鼠
    class Gerbil extends Rodent{
    void say(){System.out.println("hi,我是 Gerbil");}
    } //大颊鼠
    class Hamster extends Rodent{
    void say(){System.out.println("hi,我是 Hamster");}
    } //啮(nie四声)齿动物大家族
    public class RodentHome {
    public static void instroduce(Rodent rodent){
    rodent.say();
    } public static void instroduceAll(Rodent[] rodents){
    for(Rodent r: rodents){
    instroduce(r);
    }
    } public static void main(String[] args) {
    Rodent[] rodents = {
    new Mouse(),
    new Gerbil(),
    new Hamster()
    };
    instroduceAll(rodents);
    }
    }
  10. 第十题
    package net.mindview.polymorphism;
    
    class Base{
    public void method1(){
    System.out.println("method1");
    method2();
    } public void method2(){
    System.out.println("Base method2");
    }
    } class Child extends Base{
    @Override
    public void method2() {
    System.out.println("Child method2");
    }
    } public class Test10 { public static void up(Base b){
    b.method1();
    } public static void main(String[] args) {
    Child c = new Child();
    up(c); }
    }
  11. afd
  12. adf
  13. 第十三题
    package net.mindview.polymorphism;
    import static net.mindview.util.Print.*;
    //这是一个共享类
    class Shared {
    private int refCount = ;
    private static long counter = ;
    private final long id = counter++; public Shared(){
    println("Creating "+this);
    } public void addRef(){
    refCount ++;
    } protected void dispose(){
    if(--refCount ==){
    println("Disposing " + this);
    }
    } @Override
    public String toString() {
    return "Shared " + id;
    } @Override
    protected void finalize() throws Throwable {
    if(refCount != ){
    println("Error, 引用计数不为0");
    }
    super.finalize();
    }
    } //组成类
    class Composing{
    private Shared shared;
    private static long counter = ;
    private final long id = counter ++; public Composing(Shared shared){
    println("Creating "+ this);
    this.shared = shared;
    shared.addRef();
    } protected void dispose() {
    println("dispose " + this);
    shared.dispose();
    }
    @Override
    public String toString() {
    return "Composing " + id;
    } } //引用计数
    public class ReferenceCounting { public static void main(String[] args) {
    // TODO Auto-generated method stub
    Shared shared = new Shared();
    Composing[] composing = {
    new Composing(shared),
    new Composing(shared),
    new Composing(shared),
    new Composing(shared),
    new Composing(shared),
    new Composing(shared)
    };
    for(Composing c:composing){
    c.dispose();
    }
    }
    }
  14. fa
  15. dfa
  16. 第十六题
    package net.mindview.polymorphism;
    
    class AlertStatus {
    @Override
    public String toString() {
    return "AlertStatus";
    }
    } class StartStatus extends AlertStatus {
    @Override
    public String toString() {
    return "StartStatus";
    }
    } class EndStatus extends AlertStatus {
    @Override
    public String toString() {
    return "EndStatus";
    }
    } class PauseStatus extends AlertStatus {
    @Override
    public String toString() {
    return "PauseStatus";
    }
    } class Music4 {
    AlertStatus as = new StartStatus(); public void pause(){
    as = new PauseStatus();
    } public void end(){
    as = new EndStatus();
    } public void currentStatus(){
    System.out.println(as);
    }
    } public class Starship { public static void main(String[] args) {
    Music4 m = new Music4();
    m.currentStatus();
    m.pause();
    m.currentStatus();
    m.end();
    m.currentStatus();
    }
    }
  17. 第十七题
    package net.mindview.polymorphism;
    //基类-自行车
    class Cycle{
    public int wheels(){
    return ;
    }
    } //子类-单轮车
    class Unicycle extends Cycle{
    public int wheels(){
    return ;
    } public void balance(){
    System.out.println("Unicycle balance");
    }
    } //子类-双轮车
    class Bicycle extends Cycle{
    public int wheels(){
    return ;
    }
    public void balance(){
    System.out.println("Bicycle balance");
    }
    } //子类-三轮车
    class Tricycle extends Cycle{
    public int wheels(){
    return ;
    }
    } public class CycleCompetition {
    public static void ride(Cycle cycle){
    System.out.println(cycle.wheels());
    } public static void main(String[] args) {
    Cycle[] cycle = {
    new Cycle(),
    new Unicycle(),
    new Bicycle(),
    new Tricycle()
    };
    //((Cycle)cycle[0]).balance();//编译不通过
    ((Unicycle)cycle[]).balance();
    ((Bicycle)cycle[]).balance();
    }
    }
05-11 16:04
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