„Hallo, Amigo!“
„Hallo, Kapitän Eichhörnchen, Sir!“
„Riechst du das, Soldat?“
„Nein, das tue ich nicht.“
„Der Geruch kommt höchstwahrscheinlich von Ihrem Terminal. Mal sehen, was Sie dort machen.“
„Huh? Wie kann Code stinken?“
„Stimmt, es kann definitiv nicht stinken … aber es hat oft einen Geruch.“
„Kapitän, ich entwickle ein neues Personalmanagementsystem für das Schiff. Sehen Sie, das Projekt ist fast fertig.“
„Nun, es ist an der Zeit, dass Sie Zen im Refactoring erreichen. Erst dann können Sie Ihren Code bereinigen. Kontaktieren Sie Agent IntelliJ IDEA für Ihren Auftrag. Er wird Ihnen alle Anweisungen geben.“
„Ja, Sir! Ich führe Ihren Befehl aus, Sir.“
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 1)
It's time for a little refactoring. Wikipedia says, "Refactoring
or reorganizing code is the process of changing the internal structure of a program, without
affecting its external behavior and with an aim to making it easier to understand.
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Refactoring (part 2)
2.1. Extract a subclass.
2.1.1. Add the Soldier class to the human package.
2.1.2. Get rid of the isSoldier field.
2.1.3. Move the necessary methods from Human to Soldier.
2.1.4. Update the Human constructor's signature.
2.2. Pull up the body of the constructor.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 3)
3.1. Push down a field. Push down the course field to the appropriate class. Make it private.
3.2. Push down a method. Push down the getter for the course field to the appropriate class.
3.3. Extract an interface.
3.3.1. Create an Alive interface in the human package.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 4)
4.1. Replace inheritance with delegation.
4.1.1. The University class must not inherit Student.
4.1.2. The University class must have a students list. Don't forget to initialize it.
4.1.3. Add a setter and getter for students.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 5)
5.1. Create a template method.
5.1.1. Add a String getPosition() method to the Human class. It should return the string "Person".
5.1.2. Override this method in the Student and Teacher classes. The method should return "Student" and "Teacher", respectively.
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Refactoring (part 6)
6.1. Replace a parameter with a set of specialized methods. Replace the Student class's setValue() method
with specialized setCourse() and setAverageGrade() methods.
6.2. Add a parameter. Add a double parameter to the getStudentWithAverageGrade() method so the average grade of the required student.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 7)
7.1. Parameterize a method. Replace the incAverageGradeBy01() and incAverageGradeBy02() methods
with an incAverageGrade(double delta) method.
7.2. Pass an entire object. Rewrite the addStudentInfo() method so that it
takes a Student object as an argument.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 8)
8.1. Remove a setter. Remove the setId() method. The id field should be set only when
the object is created.
8.2. Hide a method (field). Change the visibility of the nextId field to match
the area where it is used.
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Refactoring (part 9)
9.1. Self-encapsulate a field. Rewrite the incAverageGrade() method, using a setter and getter to access averageGrade.
9.2. Replace an array field with an object. Replace the int[] size array with an instance of a new Size type,
containing the following public fields: int height and int weight.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 10)
Understand the code in the car package.
10.1. Replace a constructor with a factory method.
10.1.1. Declare Truck, Sedan, and Cabriolet classes that inherit Car.
10.1.2. Add constructors that have an int numberOfPassengers constructors.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 11)
11.1. Replace an error code with an exception. Rewrite the fill(double numberOfGallons)
method to throw an Exception if there is an error.
11.2. Decompose a conditional expression.
11.2.1. Add and implement a method in the Car class that determines whether the passed date belongs to
summer.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 12)
12.1. Combine conditional expressions.
12.1.1. In the Car class, add a private method that indicates whether passengers can be carried:
boolean canPassengersBeCarried(). The method should return true if
the driver is available (isDriverAvailable) and there is fuel.
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Refactoring (part 13)
Understand the code in the user package.
13.1. Extract a method. Add a printInfo() method that displays the first and last name
on the console, formatted as follows -
First name: Jason;
Last name: Slater.
Replace the duplicate code in printUsers() with a method call.
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Java Multithreading, Level 5, Lektion 16
Refactoring (part 14)
14.1. Move a field. Replace the isAnnaMale and isRomanMale fields with a male field in the appropriate class.
Add a setter and getter for the new field (when choosing method names, consider the field type).
14.2. Extract a class.
14.2.1. Add an Address class to the user package.
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Refactoring (part 15)
Great. You've mastered basic refactoring techniques: Pull up a field, pull up a method, Encapsulate a collection, extract a subclass, pull up the body of a constructor, push down a method, push down a field, extract an interface, collapse a hierarchy, replace inheritance with delegation.