java编程思想第四版第八章习题
- 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 - （略）
- （略）
- 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();
} } } - 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);
}
} - 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);
} } - 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);
} } - 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);
} } - 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);
}
} - 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); }
} - afd
- adf
- 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();
}
}
} - fa
- dfa
- 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();
}
} - 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();
}
}
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