Design Pattern 01 Observer pattern (Java)

1 ImportJava.util.Map;2 ImportJava.util.HashMap;3 ImportJava.util.Observer;4 Importjava.util.Observable;5 6 //Student Class (Student) can be observed after inheriting observable7 classStudentextendsobservable{8     //Properties9     PrivateString name;Ten     Private BooleanIssleep =false; One     Private BooleanIslate =false; A     //constructor Function -      PublicStudent () {} -      PublicStudent (String name) { the          This. Name =name; -     } -     //Sleep Behavior -      Public voidsleep () { +SYSTEM.OUT.PRINTLN (name + "is sleeping"); -Issleep =true; + setchanged (); ANotifyobservers ("Sleep"); at          -     } -     //Late Behavior -      Public voidlate () { -SYSTEM.OUT.PRINTLN (name + "was lated"); -Islate =true; in setchanged (); -Notifyobservers ("Late"); to     } + } - //Teacher Class (Teacher) implements observer interface becomes observer the classTeacherImplementsobserver{ *     //parameter arg as key, the response triggered by this parameter is stored in the map as value $     Privatemap<string,string> info =NewHashmap<string,string>();Panax Notoginseng      PublicTeacher () { -Info.put ("Sleep", "wakeup!wakeup!"); theInfo.put ("Late", "Come in."); +     } A     //to add a key-value pair the      Public BooleanAddsay (String k,string v) { +         returnInfo.put (k,v) = =NULL?false:true; -     } $ @Override $      Public voidUpdate (Observable o,object arg) { -String say =Info.get (ARG); -             if(Say = =NULL){ the                 return; -             }WuyiSystem.out.println ("Teacher:" +say); the     } - } Wu //class Teacher (CLASSHEAD) realizes observer interface becomes observer - classClassheadImplementsobserver{ About     Privatemap<string,string> info =NewHashmap<string,string>(); $      PublicClasshead () { -Info.put ("Sleep", "Gooutwashbaface"); -Info.put ("Late", "cleantheroom!"); -     } A      Public BooleanAddsay (String k,string v) { +         returnInfo.put (k,v) = =NULL?false:true; the     } - @Override $      Public voidUpdate (Observable o,object arg) { theString say =Info.get (ARG); the             if(Say = =NULL){ the                 return; the             } -System.out.println ("Classhead:" +say); in     } the } the  Public classobserverdemo{ About      Public Static voidMain (string[] arguments) { theStudent Tom =NewStudent ("Tom"); theTom.addobserver (Newclasshead ()); theTom.addobserver (NewTeacher ()); +  -System.out.println ("with" +tom.countobservers () + "Observer in the observation of Tom"); the tom.sleep ();Bayi tom.late (); the     } the}

Design Pattern 01 Observer pattern (Java)