Computer Programming 2

Lecture 9:Object Oriented Programming

Array Of Objects

Prepared & Presented by: Mahmoud Rafeek

Alfarra

MINISTRY OF EDUCATION & HIGHER EDUCATIONCOLLEGE OF SCIENCE AND TECHNOLOGY (CST)KHANYOUNIS- PALESTINE

و من يتِق الله ...عليك بتقوى الله ان كنت غافال يأتيك باألرزاق من حيث ال تدريفكيف تخاف الفقر والله رازقا

فقد رزق الطير والحوت في البحر ومن ظن أن الرزق يأتي بقوة ما أكل العصفور شيئا مع النسرتزول عن الدنيا فإنك ال تدري

إذا جن عليك الليل هل تعيش إلى الفجرفكم من صحيح مات من غير علة

وكم من سقيم عاش حينا من الدهروكم من فتى أمسى وأصبح ضاحكا

وأكفانه في الغيب تنسج وهو ال يدريفمن عاش ألفا وألفين

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What is Array of object? Why is Array of objects?How to create an array of objects?Example

What is Array of object?What is Array of object?

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So far we have looked at an array of primitive types.

integers could also use doubles, floats, characters…

Often want to have an array of objects

Students, Books, Loans ……

Why is Array of objectsWhy is Array of objects??

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Book

Class

Create objects

Obj1

Obj2

Obj3

Obj n

How to search, sort, Print all ….?

Book

Class

Create objects

Obj1

Obj2

Obj3

Obj n

.…

[0]

[1]

[2]

[n]

By index of arrayWe can make all the

manipulation operations

How to create an array of objectsHow to create an array of objects??

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1. Declare the array•private Student studentList[]; //this declares studentList

2 .Create the array• studentList = new Student[10];

•this sets up 10 spaces in memory that can hold references to Student objects

3. Create Student objects and add them to the array: studentList[0] = new Student("Cathy", "Computing");

How to create an array of objectsHow to create an array of objects??

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4.

Manag

e

2. Create objects of

Obj1Obj2

Obj3

Obj4

3. objects

1. Create objects of

Example: Array Of PCExample: Array Of PC

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1. public class PC {2. private static int PCcounter;3. private static String code;4. private static String YOM;5. private static int cost;6. public PC() {7. PCcounter++;8. code = "no code";9. YOM = "1990"; }10. public PC(String code, String YOM, int cost) {11. PCcounter++;12. this.code =code;13. this.YOM = YOM;14. this.cost = cost; }15. public void info(){16. System.out.println("---------------------------");17. System.out.println("Code: "+code+"\nYOM: "+YOM+"\ncost: "+cost); }

}

Example: Array Of PCExample: Array Of PC

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91. public class Record {2. PC [] rec = new PC[50];3. private int count;4. public Record() {5. count =0; }6. public void insert(String code, String YOM, int cost){7. if(count<50){8. PC p = new PC(code, YOM,cost);9. rec[count] = p;10. count++;}11. else System.out.println("Sorry, The record is complete"); }12. public void insert(){13. if(count<50){14. PC p = new PC();15. rec[count] = p;16. count++;}17. else System.out.println("Sorry, The record is complete"); }18. public void PrintAll(){19. System.out.println("Count of PC: "+count);20. for(int i =0; i<count; i++)21. rec[i].info(); } }

Example: Array Of PCExample: Array Of PC

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101. public class RecordPC {2. 3. public static void main(String[] args) {4. 5. Record rec1 = new Record();6. rec1.insert("pc123","2010",450);7. rec1.insert("pc124","2010",455);8. rec1.insert("pc125","2010",460);9. rec1.PrintAll();10. }11. }

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Java Applet