Sw203 Lecture7 Method Override

Объект хандлагат програмчлалын хэл Java Хичээл : C S203 Багш : Д.Энхжаргал Mongolia University of Science & Technology Лекц №7. Даран тодорхойлсон функц (Method override)

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Дахин тодорхойлсон функц

Method Override Удамшил Method override: Ижил нэртэй ялгаатай функц тодорхойлох Багш __ мэдээлэл Хичээлийн код calc__salary(age) Ажилтан _ мэдээлэл Нэр Төрсөн огноо Нас Хаяг calc__age(birthday) calc__salary(age)

Course CS Course Math Course Cisco Course Programming Course Basic Math Course Advanced Math Course extends extends extends extends extends extends Method override -ийн шаардлага

Course getCourseCredit()::3 CS Course Math Course Cisco Course Programming Course Basic Math Course extends extends extends extends extends extends Advanced Math Course Онцгой тохиолдол Учир нь: Course классаас удамших классууд нь бүгд 3 кредитийн хичээлүүд бөгөөд харин Advanced Math Course нь 4 кредитийн хичээл Асуудлыг хэрхэн шийдэх вэ? Method override -ийн шаардлага Course 1 getCourseCredit():: 4 extends ×

Course getCourseCredit()::3 CS Course Math Course Cisco Course Programming Course Basic Math Course extends extends extends extends extends extends Advanced Math Course getCourseCredit()::4 Онцгой тохиолдол Учир нь: Course классаас удамших классууд нь бүгд 3 кредитийн хичээлүүд бөгөөд харин Advanced Math Course нь 4 кредитийн хичээл Асуудлыг хэрхэн шийдэх вэ? Эх классын гишүүн функцтэй ижил дүрслэлтэй гишүүн функцыг түүнд тодорхойлж өгөх нь зүйтэй Method override -ийн шаардлага

private default protected public public protected default private ,[object Object],[object Object],[object Object],[object Object],[object Object],Харин эсрэгээр боломжгүй Method override хийх үед хандалтыг хэрхэн тодорхойлох вэ?

Method Override - Жишээ ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],Method Override - Жишээ public class Student { private String id; private String name; private School school; private Grade[] grades; public Grade[] getGrades() { return grades; } public void setGrades(Grade[] grades) { this.grades = grades; } public String getId() { return id; } public void setId(String id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public School getSchool() { return school; } // дараагийн хуудас …

[object Object],Method Override - Жишээ // үргэлжлэл … public Grade getGrade(Course course) { if (grades == null) { return null; } for (int i = 0; i < grades.length; i++) { Grade grade = grades[i]; if (grade.getCourse() == course) { return grade; } } return null; } public boolean isPassed(Course course) { Grade grade = getGrade(course); if (grade == null) { return false; } else { return grade.getScore() > 50; } } }

[object Object],[object Object],[object Object],[object Object],Method Override - Жишээ public class BachelorStudent extends Student { } public class MasterStudent extends Student { } public class DoctorateStudent extends Student { } Student BachelorStudent DoctorateStudent MasterStudent extends

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Method Override - Жишээ

[object Object],[object Object],[object Object],[object Object],Method Override - Жишээ public class BachelorStudent extends Student { public boolean isPassed(Course course) { // method override Grade grade = getGrade(course); if (grade == null) { return false; } else { return grade.getScore() >= 74 ; } } } public class MasterStudent extends Student { public boolean isPassed(Course course) { // method override Grade grade = getGrade(course); if (grade == null) { return false; } else { return grade.getScore() >= 82; } } }

[object Object],Method Override - Жишээ public class TestClass { public static void main(String[] args) { // сургууль объектыг үүсгэе. School ktmc = new School(); ktmc.setName("KTMC"); ktmc.setAddress("Sansar, Ulaanbaator, Mongolian"); // зарим хичээл объектууд үүсгэе Course sw203 = new Course("SW203", "Object-oriented Programming", 3); Course sw508 = new Course("SW508", "Object-oriented Analysis and Design", 3); Course sw811 = new Course("SW811", "Advanced Artificial Intelligence", 3); // Бакалаврын оюутан гэсэн объект үүсгэе Student bachelor = new BachelorStudent(); bachelor.setId("SW050001"); bachelor.setName("Baatar"); bachelor.setSchool(ktmc); bachelor.setGrades(new Grade[]{new Grade("Fall", 2006, sw203)}); // Магистр оюутан гэсэн объект үүсгэе Student master = new MasterStudent(); master.setId("SW020001"); master.setName("Chimgee"); master.setSchool(ktmc); master.setGrades(new Grade[]{new Grade("Fall", 2006, sw508)}); // Докторант оюутан гэсэн объект үүсгэе Student doctorate = new DoctorateStudent(); doctorate.setId("SW990001"); doctorate.setName("Tuya"); doctorate.setSchool(ktmc); doctorate.setGrades(new Grade[]{new Grade("Fall", 2006, sw811)});

[object Object],[object Object],Method Override - Жишээ // өмнөх хуудсын үргэлжлэл … // одоо оюутандуудыг оноогоор дүгнэе // тэгээд оюутнуудыг дүгнэсэн оноо зөв олгогдсон эсэхийг шалгаж үзье. bachelor.getGrades()[0].setScore(81); System.out.println("bachelor student passed SW203? " + bachelor.isPassed(sw203)); bachelor.getGrades()[0].setScore(73.9); System.out.println("bachelor student passed SW203? " + bachelor.isPassed(sw203)); master.getGrades()[0].setScore(81); System.out.println("master student passed SW511? " + master.isPassed(sw508)); master.getGrades()[0].setScore(87); System.out.println("master student passed SW511? " + master.isPassed(sw508)); doctorate.getGrades()[0].setScore(48); System.out.println("doctorate student passed SW811? " + doctorate.isPassed(sw811)); doctorate.getGrades()[0].setScore(61); System.out.println("doctorate student passed SW811? " + doctorate.isPassed(sw811)); } } bachelor student passed SW203? true bachelor student passed SW203? false master student passed SW511? false master student passed SW511? true doctorate student passed SW811? false doctorate student passed SW811? false

Method Override – санамж ,[object Object],[object Object],[object Object],[object Object],// from Student.class... public boolean isPassed(Course course) { Grade grade = getGrade(course); if (grade == null) { return false; } else { return grade.getScore() > 50; } } // from BachelorStudent.class... public boolean isPassed(Course course) { Grade grade = getGrade(course); if (grade == null) { return false; } else { return grade.getScore() >= 74 ; } } Ижил дүрслэл Ялгаатай үүрэг

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Method Override - Жишээ

Хийсвэрлэлт ийг цөөн үгээр ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Student BachelorStudent DoctorateStudent MasterStudent extends

Оюутан классын програмын бичлэгийг авч үзье. public class Student { String code; String name; int credit; double GPA; public String getCode() { return code; } public void setCode(String code) { this.code = code; } public int getCredit() { return credit; } public void setCredit(int credit) { this.credit = credit; } public double getGPA() { return GPA; } public void setGPA(double gpa) { GPA = gpa; } public String getName() { return name; } public void setName(String name) { this.name = name; } } Дээр Оюутан класс тодорхойлсон байна. Оюутан классд 4 гишүүн өгөгдөл ба тэдгээрт утга олгох, тэдгээрийн утгыг авч унших mutator methods буюу setter ба getter methods -ийг тодорхойлов. Оюутан классд тухайн оюутан нь төгсөгч оюутан мөн эсэхийг шалгах үүрэгтэй isCraduator нэртэй гишүүн Функц шаардлагатай гэж үзье.

Оюутан классын програмын бичлэгийг авч үзье. public class Student { String code; String name; int credit; double GPA; public String getCode() { return code; } public void setCode(String code) { this.code = code; } public int getCredit() { return credit; } public void setCredit(int credit) { this.credit = credit; } public double getGPA() { return GPA; } public void setGPA(double gpa) { GPA = gpa; } public String getName() { return name; } public void setName(String name) { this.name = name; } isGraduator ( ){ ... } } Асуулт: isGraduator( ) гишүүн функцын аргумент, гүйцэтгэх үйлдэл, буцаах утга ямар байх вэ? Хариулт: Бодит амьдралын шаардлагатай уялдуулан хийсвэрлэнэ.

[object Object],Оюутан классын програмын бичлэгийг авч үзье. public class Student { String code; String name; int credit; double GPA; public String getCode() { return code; } public void setCode(String code) { this.code = code; } public int getCredit() { return credit; } public void setCredit(int credit) { this.credit = credit; } public double getGPA() { return GPA; } public void setGPA(double gpa) { GPA = gpa; } public String getName() { return name; } public void setName(String name) { this.name = name; } public boolean isGraduator(int credit, double gpa){ if ((gpa>=2.0) && (this.credit>=122)) {return true;} else return false;} }

Method Override - Жишээ ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],Method Override - Жишээ public class BachelorStudent extends Student { public boolean isGraduator(int credit, double gpa){ if ((gpa>=2.5) && (this.credit>=60)) {return true;} else return false; } } public class MasterStudent extends Student { public boolean isGraduator(int credit, double gpa){ if ((gpa>=3.5) && (this.credit>=33)) {return true;} else return false; } }

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Constructor override- Жишээ

[object Object],Constructor override- Жишээ public class Course { private String code; private String name; private int credit; private Teacher teacher; public Course(String id, String name, int credit) { this.code = id; this.name = name; this.credit = credit; } public int getCredit() { return credit; } public String getCode() { return code; } public String getName() { return name; } public Teacher getTeacher() { return teacher; } public void setTeacher(Teacher teacher) { this.teacher = teacher; } } Байгуулагч функц Гишүүн өгөгдөл Классын нэр

[object Object],[object Object],[object Object],Constructor override- Жишээ public class ProgrammingCourse extends Course { public ProgrammingCourse() { super("SW203", "Programming Course", 3); } } public class ProgrammingCourse extends Course { public ProgrammingCourse(String id, String name, int credit) { super(id, name, credit); } } Жишээ 1 Жишээ 2

[object Object],[object Object],Constructor override- Жишээ public class Course { private String code; private String name; private int credit; private Teacher teacher; public Course(String id, String name, int credit) { this.code = id; this.name = name; this.credit = credit; } ... ... ... } public class ProgrammingCourse extends Course { public ProgrammingCourse(String id, String name, int credit) { super(id, name, credit); } } Ижил дүрслэл

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Constructor override- Жишээ

[object Object],Constructor override- Жишээ public class ProgrammingCourse extends LeadingLecture { public ProgrammingCourse(String id, String name, int credit) { super(id, name, credit); this.sessions = new AccompanyingSession[1]; this.sessions[0] = new Laboratory(this, id, name + " Laboratory"); } } Эх классын байгуулагчийг дуудах мөр хамгийн эхэнд байна. Бусад кодыг дараа нь нэмж бичиж болно.

[object Object],Constructor override- Жишээ public class LeadingLecture extends Course { protected AccompanyingSession[] sessions; public LeadingLecture(String id, String name, int credit) { super(id, name, credit); } public AccompanyingSession[] getSessions() { return sessions; } } public class AccompanyingSession extends Course { private LeadingLecture lecture; /** дагалдах цагууд нь кредитгүй */ public AccompanyingSession(LeadingLecture lecture, String id, String name) { super(id, name, 0); // Кредитгүй this.lecture = lecture; System.out.println ("created accompanying session for " + name); } public LeadingLecture getLecture() { return lecture; } } public class Seminar extends AccompanyingSession { public Seminar(LeadingLecture lecture, String id, String name) { super(lecture, id, name); } } public class Laboratory extends AccompanyingSession { public Laboratory(LeadingLecture lecture, String id, String name) { super(lecture, id, name); }}

[object Object],[object Object],Constructor override- Жишээ public class TestClass { public static void main(String[] args) { System.out.println("Creating SW203..."); Course SW203 = new ProgrammingCourse("SW203", "Object-oriented Programming", 3); System.out.println(); System.out.println("Creating MA201..."); Course MA201 = new MathCourse("MA201", "Algebra II", 3); System.out.println(); System.out.println("Creating FL350..."); Course EN350 = new LanguageCourse(“FL350", "Business English II", 4); } } Creating SW203... created accompanying session for Object-oriented Programming Laboratory Creating MA201... Creating FL350... created accompanying session for Business English II Seminar I created accompanying session for Business English II Seminar II

Boat() Gette r functions & Setter functions tellAboutSelf() StateRegistrationNo Length Manufacturer Year Boat Sail Boat() Gette r functions & Setter functions tellAboutSelf() keelDepth numberSails motorType Sailboat Power Boat() Gette r functions & Setter functions tellAboutSelf() numberOfEngines fuelType PowerBoat

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