Chapter 5 Constructors

1. Chapter 5Constructors Constructors

2. 1 Constructors Constructors

3. 2 Overloading Constructors

4. 3 ... Constructors

5. 4 Problem Constructors

6. 5 Solution Constructors

7. 6 Scope Constructors

8. 7 Object variables Constructors

9. Complex conjugate 8 Example public complexNumber conjugate() { complexNumber conj = new complexNumber(new cartesian(this.x,-this.y); return conj; } add public complexNumber add (complexNumber operand) { double RealSum = this.x + operand.x; double ImSum = this.y + operand.y; return new complexNumber(new cartesian(RealSum, ImSum)); } Do I need to expose the internal state Constructors

10. multiply 9 Private public complexNumber mult (complexNumber operand) { double RealProd = this.Real()*operand.Real() - this.Imaginary()+operand.Imaginary(); double ImProd = this.Real()*operand.Imaginary() + this.Imaginary()*operand.Real(); return new complexNumber(new cartesian(RealProd, ImProd)); } Here I am protecting one part of a class from changes in another part. multiply works if the storage of state change takes longer to execute add needs changing if the state changes executes fast Constructors

11. 10 Storing state How to store state? public class complexNumber { private polar point; … } public class complexNumber { private cartesian point; … } How to decide? Constructors

12. 11 Printing out an object public String toString() { String Cn = "(" + x + ", " + y + "i)"; return Cn; } The output from System.out.println(objectName); Is whatever is returned by toString; override toString in the Object class Constructors

13. 12 Recap Constructors

14. 13 Inheritance Constructors

15. 14 ... Constructors

16. 15 Extends Constructors

17. 16 Core API Constructors

18. 17 Pillage then burn Constructors

19. 18 Evolution Constructors

20. 19 Access Constructors

21. 20 Object class Constructors