Arrays Class presentation

Arrays Class presentation

• 1.
  Introduction to ComputerProgramming Lab 2 Arrays Neveen Reda
• 2.
  Arrays in action 0There are many uses for arrays 0 For example image pixels are represented using arrays Neuroph (2012)
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  Arrays in action 0 Arrays can also be used in creating grids for games. Eckert (2009)
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  Lesson Objectives After thislesson you will be able to: 3.Develop Java programs that create arrays and perform different operations on them. 5.Determine the functionality and output of any given program that performs array manipulations.
• 5.
  Arrays 0 Why arrays?  Individual variables can only hold one value at a time, Arrays can holds multiple values (Abdennadher , 2010). 0 “An array is a data structure that defines an indexed collection of a fixed number of data elements.” (Mughal & Rasmussen, 2009).
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  Arrays 0 The positionof an element in an array is called the index. 0 If array X contains 10 elements, the first element will be at position (index) '0' and the last element is at position '9' Oracle (2012)
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  Arrays Declarations 0 Allthe elements in an array have the same data type. (For example all integers, all Strings, all doubles and so on) Examples: int [] x; //x is an array of integers. double [] myArray; //myArray is an array of doubles.
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  Creating Arrays 0 Thesize if an array is fixed. It is specified when the array is created and cannot be changed (Abdennadher , 2010). x = new int[5]; //array x is now of size 5 myArray = new double[3];
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  Creating Arrays 0 Anarray can be declared and created in one statement. 0 Until this point the arrays is empty (contains default values of its declared type) Examples: int [] x = new int [5]; double [] myArray = new double [3]; int number = 10; char [] letters = new char[number];
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  Initializing Arrays Double []prices = new double [5];
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  Initializing Arrays Double []prices = {2.25, 3.0, 10.5, 5.3, 0.5}; 2.25 3.0 10.5 5.3 0.5
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  Using Arrays After creatingand initializing an array, it can be used within a program: • An element in the array can be used within a statement • The reference to the array can be used within a statement. (Abdennadher , 2010)
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  Using Arrays 0 Reassignvalue to index: 4.5 2.25 Prices[0] = 4.5; 3.0 10.5 5.3 0.5 0 Using element within a statement: if(Prices[1] >= 3.0){ Discount = 10; }
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  Array Examples 0 Writea java program that creates an array of size 3 and prints all its elements using a for loop.
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  References • Abdennadher S. (2010). Arrays. Lecture notes. • Eckert T. (2009). Bimaru - Battleship Solitaire [image]. Retrieved from: http://www.cyrket.com/p/android/com.androidcan.bimaru/ • Mughal K. A. & Rasmussen R. W. (2009). A Programmer's Guide to Java SCJP Certification. Upper Saddle River, NJ: Pearson Education. • Neuroph (2012). Image colors [image]. Retrieved from: http:// neuroph.sourceforge.net/image_recognition.html • Oracle (2012). An array of 10 elements [image]. Retrieved from: http ://docs.oracle.com/javase/tutorial/java/nutsandbolts/arrays.html