實(shí)訓(xùn)-接口與異常類

1、實(shí)訓(xùn)接口與異常類、實(shí)訓(xùn)目標(biāo)本理解接口的意義、實(shí)際應(yīng)用的一般模式及與抽象類的區(qū)別，熟 練掌握接的定義以及接口的實(shí)現(xiàn)。本掌握異常處理結(jié)構(gòu)try、catch、finally ,理解異常出現(xiàn)時(shí)和 不出現(xiàn)時(shí)程序的執(zhí)行流程。上學(xué)會(huì)使用throw拋出異常，掌握何時(shí)選擇處理異常何時(shí)選擇拋 出異常。二、實(shí)訓(xùn)內(nèi)容1、請(qǐng)按模板要求，將【代碼】替換為Java程序代碼WeatherState.javainterface WeatherState 接口 public void showState();Weather.javaclass Weather WeatherState state ; public void sh

2、ow() state .showState(); public void setState(WeatherState s) state = s; CloudyLittleState.java class CloudyLittleState implements WeatherState public void showState() System. out .print( 少云 , 有時(shí)晴 . ); / 重寫(xiě) public void showState() CloudyDayState.javaclass CloudyDayState implements WeatherState publi

3、c void showState()System. out .println( 多云 ); / 重寫(xiě) public void showState() HeavyRainState.javaclass HeavyRainState implements WeatherStatepublic void showState()System. out .println( 傾盆大雨 ); / 重寫(xiě) public void showState() LightRainState.javaclass LightRainState implements WeatherState public void show

4、State()System. out .println( 小雨 ); / 重寫(xiě) public void showState()WeatherForecast.javaclass WeatherForecast / 主類public static void main(String args ) Weather weatherBeijing = new Weather();System.out.print(n 今天白天:);weatherBeijing.setState(new CloudyDayState();weatherBeijing.show();System.out.print(n 今天

5、夜間:);weatherBeijing.setState(newLightRainState();weatherBeijing.show();System.out.print( 轉(zhuǎn) : );weatherBeijing.setState(newHeavyRainState();weatherBeijing.show();System.out .print(n 明天白天: );weatherBeijing.setState(new LightRainState();weatherBeijing.show();System.out .print(n 明天夜間: );weatherBeijing.s

6、etState(new CloudyLittleState();weatherBeijing.show();2、請(qǐng)按模板要求，將【代碼】替換為Java程序代碼。MyDate.javapublic class MyDate publicintyear ;publicintmonth;publicintday;public MyDate( int y, int m, int d) throws InvalidDateException /聲明要產(chǎn)生的自定義異常類InvalidDateExceptionif ( y 0) throw new InvalidDateException。； elseye

7、ar = y;if ( m 12) throw new InvalidDateException。；/ 使用 throw 關(guān)鍵字拋出該異常對(duì)象 else month = m;if ( d 31) throw new InvalidDateException。；/ 使用 throw 關(guān)鍵字拋出該異常對(duì)象 else day = d;InvalidDateException.javapublic class InvalidDateException extends Exception / 聲明自定義異常類 InvalidDateException 繼承 ExceptionString message

8、;public InvalidDateException。 message =非法日期數(shù)據(jù)！；public void toShow() System. out .println( message +);TestDate.javapublicclass TestDate public static void main(String args ) try MyDate e=new MyDate(-12, 3, 83);/ 創(chuàng)建一個(gè) MyDate對(duì)象，設(shè)置構(gòu)造方法中參數(shù)不符合實(shí)際要求 catch (InvalidDateExceptione) System. out .println(不符合實(shí)際日期

9、要求！);； 當(dāng)參數(shù)不符合實(shí)際日期要求是，捕獲異常，請(qǐng)輸出異常信息3、編程題【實(shí)驗(yàn)-繼承與接口 1】(1)設(shè)計(jì)一個(gè)形狀類Shape,包含一個(gè)getArea()方法，該方法不包含實(shí)際 語(yǔ)句。(2)在Shaped基礎(chǔ)上設(shè)計(jì)圓形(Circle)、矩形(Rectangle )和梯形 (Ladder)三個(gè)子類，要求根據(jù)實(shí)際形狀重寫(xiě)getArea()方法，用于計(jì)算形狀的面 積。(3)創(chuàng)建一個(gè)應(yīng)用程序主類TestShape,在main ()方法中分別創(chuàng)建三個(gè)子 類對(duì)象，Circle c=new Circle(10);/構(gòu)造方法中給圓半徑變量賦值Rectangle r=new Rectangle(10,20)

10、;/構(gòu)造方法中給長(zhǎng)、寬變量賦值Ladder c=new Ladder(3,5,4);/構(gòu)造方法中給上底、下底和高變量賦值子類對(duì)象分別調(diào)用getArea()方法，輸出各自的面積信息。(1)新建包名：pk2,在pk2包下，將【實(shí)驗(yàn)-繼承與接口 11中形狀類Shap改為接口，修改圓形(Circle)、矩形(Rectangle)和梯形(Ladder)三個(gè)類分別實(shí)現(xiàn)接口，在不修改測(cè)試類TestShape的基礎(chǔ)上，保證執(zhí)行TestShape能夠得到與【實(shí)驗(yàn)-繼承與接口1】同樣的結(jié)果。Shape.javapackage PK2;public interface Shape public abstract d

11、ouble getArea();Circle.javapackage PK2;public class Circle implements Shapepublic Circle( float r )this . r =r ; / 設(shè)置半徑private float r ;public double getArea()return 3.14* r* r;Rectangle.javapackage PK2;public class Rectangle implements Shape private double w;private double h;public Rectangle( float

12、 w, float h) this . w=w;this . h=h;public double getArea() return w* h;Ladder.javapackage PK2;public class Ladder implements Shapeprivatefloatt ;/上底privatefloatb;/下底h)privatefloath;/高public Ladder( float t , float b, floatthis . t =t ;this . b=b;this . h=h;public double getArea()return ( t +b)* h)*1

13、/2;TestShape.javapackage PK2;public class TestShape public static void main(String口args )Circle c=new Circle(10); /構(gòu)造方法中給圓半徑變量賦 值System. out .println( area= + c.getArea();Rectangle r =new Rectangle(10,20); / 構(gòu)造方法中給 長(zhǎng)、寬變量賦值System. out .println( area= + r .getArea();Ladder l =new Ladder(3,5,4);/ 構(gòu)造方法中給上底、下底和高變量賦值System. out .println( area= + l .getArea();