Bölüm 7 - Diziler İçerik 7.1 Giriş 7.2 Diziler 7.3 Dizileri Tanımlama 7.4 Dizileri Kullanan Örnekler 7.5 Referanslar ve Referans Parametreler.

... konulu sunumlar: "Bölüm 7 - Diziler İçerik 7.1 Giriş 7.2 Diziler 7.3 Dizileri Tanımlama 7.4 Dizileri Kullanan Örnekler 7.5 Referanslar ve Referans Parametreler."— Sunum transkripti:

1 Bölüm 7 - Diziler İçerik Giriş Diziler Dizileri Tanımlama Dizileri Kullanan Örnekler Referanslar ve Referans Parametreler Dizinin Metoda Geçişi Dizileri Sıralama Dizilerde Arama: Lineer Arama ve Bölerek Arama Çok boyutlu Diziler

2 7.1 Giriş Diziler Veri Yapıları
Aynı veri tipindeki datalarla ilişkilendirme Remain same size once created Sabit-uzunluklu girişler

3 7.2 Diziler Dizi Değişkenlerin gruplanması Referans tipleri
Tabi aynı tipteki verilerin Referans tipleri

4 c[ 0 ] -45 6 72 1543 -89 62 -3 1 6453 78 Dizi ismi(bu dizinin bütün elemanları aynı isme sahiptir. , c) c[ 1 ] c[ 2 ] c[ 3 ] c[ 4 ] c[ 5 ] c[ 6 ] c[ 7 ] c[ 8 ] c[ 9 ] c dizisindeki elementlerin indexleri c[ 10 ] c[ 11 ] Fig. 7.1 A 12-element array.

5 7.2 Diziler (devam) Index Köşeli parantezlerde pozisyon numarası
pozitif integer yada integer üreten işlem olmalı a = 5; b = 6; c[ a + b ] += 2; c[ 11 ] ‘deki veriye 2 ekler

6 7.2 Diziler (devam) Dizi c inceleme c is the dizi ismi
c.length dizi c’nin uzunluğunu verir. c 12 elemente sahiptir. ( c[0], c[1], … c[11] ) c[0] değeri –45 tir.

7 7.3 Dizileri Tanımlama ve Oluşturma
Diziler bellekte yer işgal eden objelerdir. Anahtar kelime new ile oluşturulur. int c[] = new int[ 12 ]; Aşağıdaki ifade de aynı işlemi gerçekleştirir int c[]; // declare array variable c = new int[ 12 ]; // create array Objelerinden de diziler oluşturulabilir. String b[] = new String[ 100 ];

8 7.4 Dizileri Kullanan Örnekler
Dizileri tanımlama Dizileri oluşturma Dizilere ilk değer verme Dizi elemanları ile işlem yapma

9 7.4 Dizileri Kullanan Örnekler(Devam.)
Dizileri oluşturma ve ilk değer verme Dizi tanımlama Dizi oluşturma Dizi elementlerine ilk değer verme

10 Create 10 ints for array; each int is initialized to 0 by default
// Fig. 7.2: InitArray.java // Creating an array. import javax.swing.*; 4 public class InitArray { 6 public static void main( String args[] ) { int x[]; // dizi tanımlama 10 x = new int[ 10 ]; // diziyi oluşturma 12 String output = "Index\tValue\n"; 14 // append each array element's value to String output for ( int counter = 0; counter < x.length; counter++ ) output += counter + "\t" + x[ counter ] + "\n"; 18 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 21 JOptionPane.showMessageDialog( null, outputArea, "Initializing an Array of int Values", JOptionPane.INFORMATION_MESSAGE ); 25 System.exit( 0 ); 27 } // end main 29 30 } // end class InitArray InitArray.java Line 9 Declare array as an array of ints Line 11 Create 10 ints for array; each int is initialized to 0 by default Line 16 array.length returns length of array Line 17 array[counter] returns int associated with index in array Create 10 ints for array; each int is initialized to 0 by default Declare array as an array of ints array.length returns length of array array[counter] returns int associated with index in array

11 InitArray.java Each int is initialized to 0 by default

12 7.4 Dizileri Kullanan Örnekler(Devam.)
Diziyi ilk değer vererek oluşturma Değer listesi kullanma Değerler küme parantezi içine yazılır. ({}) Değerler birbirinden virgül ile ayrılır. int n[] = { 10, 20, 30, 40, 50 }; 5 elemanlı dizi oluşturur. Index değerleri 0, 1, 2, 3, 4 New anahtar kelimesine ihtiyaç yoktur.

13 Declare array as an array of ints
// Fig. 7.3: InitArray.java // Initializing an array with a declaration. import javax.swing.*; 4 public class InitArray { 6 public static void main( String args[] ) { // array initializer specifies number of elements and // value for each element int x[] = { 32, 27, 64, 18, 95, 14, 90, 70, 60, 37 }; 12 String output = "Index\tValue\n"; 14 // append each array element's value to String output for ( int counter = 0; counter < array.length; counter++ ) output += counter + "\t" + x[ counter ] + "\n"; 18 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 21 JOptionPane.showMessageDialog( null, outputArea, "Initializing an Array with a Declaration", JOptionPane.INFORMATION_MESSAGE ); 25 System.exit( 0 ); 27 } // end main 29 30 } // end class InitArray Declare array as an array of ints InitArray.java Line 11 Declare array as an array of ints Line 11 Compiler uses initializer list to allocate array Compiler uses initializer list to allocate array

14 Each array element corresponds to element in initializer list
InitArray.java Each array element corresponds to element in initializer list Each array element corresponds to element in initializer list

15 7.4 Dizileri Kullanan Örnekler(Devam.)
Her bir dizi elemanının değerini hesaplama 10-elemanlı dizinin elemanları için çift sayı üretmek

16 Declare array as an array of ints
// Fig. 7.4: InitArray.java // Initialize array with the even integers from 2 to 20. import javax.swing.*; 4 public class InitArray { 6 public static void main( String args[] ) { final int ARRAY_LENGTH = 10; // constant int array[]; // reference to int array 11 array = new int[ ARRAY_LENGTH ]; // create array 13 // calculate value for each array element for ( int counter = 0; counter < array.length; counter++ ) array[ counter ] = * counter; 17 String output = "Index\tValue\n"; 19 for ( int counter = 0; counter < array.length; counter++ ) output += counter + "\t" + array[ counter ] + "\n"; 22 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 25 Declare array as an array of ints InitArray.java Line 10 Declare array as an array of ints Line 12 Create 10 ints for array Line 16 Use array index to assign array value Create 10 ints for array Use array index to assign array value

17 InitArray.java 26 JOptionPane.showMessageDialog( null, outputArea,
"Initializing to Even Numbers from 2 to 20", JOptionPane.INFORMATION_MESSAGE ); 29 System.exit( 0 ); 31 } // end main 33 34 } // end class InitArray InitArray.java

18 7.4 Dizileri Kullanan Örnekler(Devam.)
Dizi elemanlarının toplamı Her dizi elemanı bir değer gösterdiğine göre, o değerleri toplayabiliriz.

19 Declare array with initializer list
// Fig. 7.5: SumArray.java // Total the values of the elements of an array. import javax.swing.*; 4 public class SumArray { 6 public static void main( String args[] ) { int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; int total = 0; 11 // add each element's value to total for ( int counter = 0; counter < array.length; counter++ ) total += array[ counter ]; 15 JOptionPane.showMessageDialog( null, "Total of array elements: " + total, "Sum the Elements of an Array", JOptionPane.INFORMATION_MESSAGE ); 20 System.exit( 0 ); 22 } // end main 24 25 } // end class SumArray Declare array with initializer list SumArray.java Line 9 Declare array with initializer list Lines Sum all array values Sum all array values

20 7.4 Dizileri Kullanan Örnekler(Devam.)
Histogram kullanarak dizi değerlerini grafik olarak gösterme Histogram Herbir değeri yıldız ile gösterme (*)

21 Declare array with initializer list
// Fig. 7.6: Histogram.java // Histogram printing program. import javax.swing.*; 4 public class Histogram { 6 public static void main( String args[] ) { int array[] = { 19, 3, 15, 7, 11, 9, 13, 5, 17, 1 }; 10 String output = "Element\tValue\tHistogram"; 12 // for each array element, output a bar in histogram for ( int counter = 0; counter < array.length; counter++ ) { output += "\n" + counter + "\t" + array[ counter ] + "\t"; 16 // print bar of asterisks for ( int stars = 0; stars < array[ counter ]; stars++ ) output += "*"; 20 } // end outer for 22 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 25 Declare array with initializer list Histogram.java Line 9 Declare array with initializer list Line 19 For each array element, print associated number of asterisks For each array element, print associated number of asterisks

22 Histogram.java 26 JOptionPane.showMessageDialog( null, outputArea,
"Histogram Printing Program", JOptionPane.INFORMATION_MESSAGE ); 28 System.exit( 0 ); 30 } // end main 32 33 } // end class Histogram Histogram.java

23 7.4 Dizileri Kullanan Örnekler(Devam.)
Dizi elemanlarını sayaç olarak kullanma

24 Declare frequency as array of 7 ints
// Fig. 7.7: RollDie.java // Roll a six-sided die 6000 times. import javax.swing.*; 4 public class RollDie { 6 public static void main( String args[] ) { int frequency[] = new int[ 7 ]; 10 // roll die 6000 times; use die value as frequency index for ( int roll = 1; roll <= 6000; roll++ ) frequency[ 1 + ( int ) ( Math.random() * 6 ) ]; 14 String output = "Face\tFrequency"; 16 // append frequencies to String output for ( int face = 1; face < frequency.length; face++ ) output += "\n" + face + "\t" + frequency[ face ]; 20 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 23 JOptionPane.showMessageDialog( null, outputArea, "Rolling a Die 6000 Times", JOptionPane.INFORMATION_MESSAGE ); 26 System.exit( 0 ); 28 } // end main 30 31 } // end class RollDie Declare frequency as array of 7 ints RollDie.java Line 9 Declare frequency as array of 7 ints Lines Generate 6000 random integers in range 1-6 Line 13 Increment frequency values at index associated with random number Generate 6000 random integers in range 1-6 Increment frequency values at index associated with random number

25 7.4 Dizileri Kullanan Örnekler(Devam.)
Araştırma sonuçlarını analiz etmek için dizileri kullanma 40 öğrenci yemeklerin kalitesini ölçtüler 1-10 : 1 berbat, 10 mükemmel 40 cevabı tutmak için dizi oluşturma Sonuçları özetleme

26 Declare responses as array to store 40 responses
// Fig. 7.8: StudentPoll.java // Student poll program. import javax.swing.*; 4 public class StudentPoll { 6 public static void main( String args[] ) { int responses[] = { 1, 2, 6, 4, 8, 5, 9, 7, 8, 10, 1, 6, 3, 8, 6, , 3, 8, 2, 7, 6, 5, 7, 6, 8, 6, 7, 5, 6, 6, 5, 6, 7, 5, 6, , 8, 6, 8, 10 }; int frequency[] = new int[ 11 ]; 13 // for each answer, select responses element and use that value // as frequency index to determine element to increment for ( int answer = 0; answer < responses.length; answer++ ) frequency[ responses[ answer ] ]; 18 String output = "Rating\tFrequency\n"; 20 // append frequencies to String output for ( int rating = 1; rating < frequency.length; rating++ ) output += rating + "\t" + frequency[ rating ] + "\n"; 24 JTextArea outputArea = new JTextArea(); outputArea.setText( output ); 27 Declare responses as array to store 40 responses Declare frequency as array of 11 int and ignore the first element StudentPoll.java Lines 9-11 Declare responses as array to store 40 responses Line 12 Declare frequency as array of 11 int and ignore the first element Lines For each response, increment frequency values at index associated with that response For each response, increment frequency values at index associated with that response

27 StudentPoll.java 28 JOptionPane.showMessageDialog( null, outputArea,
"Student Poll Program", JOptionPane.INFORMATION_MESSAGE ); 30 System.exit( 0 ); 32 } // end main 34 35 } // end class StudentPoll StudentPoll.java

28 7.4 Dizileri Kullanan Örnekler(Devam.)
Bazı dikkat edilmesi gerekli noktalar Bir diziyi döngü ile dolaşırken Index hiçbir zaman 0 ın aşağısına düşmemeli Index dizi uzunluğundan her zaman az olmalı Yanlış bir indexi referans verdiğiniz zaman Java ArrayIndexOutOfBoundsException oluşturur. Bölüm 15 te ayrıntılı anlatılacaktır.

29 7.5 Referanslar ve Referans Parametreler
Metodlara 2 yol ile arguman geçer: Değer yolu ile Çağırılan metoda değer kopyalanarak geçer. Java da , bütün basit veri tipleri “değer yolu ile” geçiş yapar. Referans yolu ile Metod, metodu çağıranın verisini değiştirebilir. Java da , her obje referans yolu ile metoda geçer. Java da , diziler objedir. Bu yüzden, diziler referans yolu ile geçerler.

30 7.6 Dizilerin Metodlara Geçişi
Dizi ismi parantezsiz yazılır: Array hourlyTemperatures is declared as int hourlyTemperatures = new int[ 24 ]; The method call modifyArray( hourlyTemperatures ); Passes array hourlyTemperatures to method modifyArray

31 Declare 5-int array with initializer list
// Fig. 7.9: PassArray.java // Passing arrays and individual array elements to methods. import java.awt.Container; import javax.swing.*; 5 public class PassArray extends JApplet { 7 // initialize applet public void init() { JTextArea outputArea = new JTextArea(); Container container = getContentPane(); container.add( outputArea ); 14 int array[] = { 1, 2, 3, 4, 5 }; 16 String output = "Effects of passing entire array by reference:\n" + "The values of the original array are:\n"; 19 // append original array elements to String output for ( int counter = 0; counter < array.length; counter++ ) output += " " + array[ counter ]; 23 modifyArray( array ); // array passed by reference 25 output += "\n\nThe values of the modified array are:\n"; 27 PassArray.java Line 15 Declare 5-int array with initializer list Line 24 Pass array by reference to method modifyArray Declare 5-int array with initializer list Pass array by reference to method modifyArray

32 Pass array[3] by value to method modifyElement
// append modified array elements to String output for ( int counter = 0; counter < array.length; counter++ ) output += " " + array[ counter ]; 31 output += "\n\nEffects of passing array element by value:\n" + "array[3] before modifyElement: " + array[ 3 ]; 34 modifyElement( array[ 3 ] ); // attempt to modify array[ 3 ] 36 output += "\narray[3] after modifyElement: " + array[ 3 ]; outputArea.setText( output ); 39 } // end method init 41 // multiply each element of an array by 2 public void modifyArray( int array2[] ) { for ( int counter = 0; counter < array2.length; counter++ ) array2[ counter ] *= 2; } 48 // multiply argument by 2 public void modifyElement( int element ) { element *= 2; } 54 55 } // end class PassArray PassArray.java Line 35 Pass array[3] by value to method modifyElement Lines Method modifyArray manipulates the array directly Lines Method modifyElement manipulates a primitive’s copy Lines 52 The original primitive is left unmodified Pass array[3] by value to method modifyElement Method modifyArray manipulates the array directly Method modifyElement manipulates a primitive’s copy The original primitive is left unmodified

33 The object passed-by-reference is modified
PassArray.java The object passed-by-reference is modified The primitive passed-by-value is unmodified

34 7.7 Dizilerin Sıralanması
Verileri sıralama Bubble sort Daha küçük değer “bubble” olarak adlandırılır ve yönü yukarı ya doğrudur. Daha büyük değer “sink” olarak adlandırılır ve yönü aşağıya doğrudur. Diziyi birden fazla dolaşabilmek için içiçe döngü kullanılır. Her geçişte iki eleman çifti karşılaştırılır. Çift artış sırasındaysa (veya eşitse) dokunulmaz. Çift azalış sırasındaysa değiştokuş yapılır indexler arasında

35 Declare 10-int array with initializer list
// Fig. 7.10: BubbleSort.java // Sort an array's values into ascending order. import java.awt.*; import javax.swing.*; 5 public class BubbleSort extends JApplet { 7 // initialize applet public void init() { JTextArea outputArea = new JTextArea(); Container container = getContentPane(); container.add( outputArea ); 14 int array[] = { 2, 6, 4, 8, 10, 12, 89, 68, 45, 37 }; 16 String output = "Data items in original order\n"; 18 // append original array values to String output for ( int counter = 0; counter < array.length; counter++ ) output += " " + array[ counter ]; 22 bubbleSort( array ); // sort array 24 output += "\n\nData items in ascending order\n"; 26 BubbleSort.java Line 15 Declare 10-int array with initializer list Line 23 Pass array by reference to method bubbleSort to sort array Declare 10-int array with initializer list Pass array by reference to method bubbleSort to sort array

36 Method bubbleSort receives array reference as parameter
// append sorted\ array values to String output for ( int counter = 0; counter < array.length; counter++ ) output += " " + array[ counter ]; 30 outputArea.setText( output ); 32 } // end method init 34 // sort elements of array with bubble sort public void bubbleSort( int array2[] ) { // loop to control number of passes for ( int pass = 1; pass < array2.length; pass++ ) { 40 // loop to control number of comparisons for ( int element = 0; element < array2.length - 1; element++ ) { 45 // compare side-by-side elements and swap them if // first element is greater than second element if ( array2[ element ] > array2[ element + 1 ] ) swap( array2, element, element + 1 ); 50 } // end loop to control comparisons 52 } // end loop to control passes 54 } // end method bubbleSort BubbleSort.java Line 36 Method bubbleSort receives array reference as parameter Lines Use loop and nested loop to make passes through array Lines If pairs are in decreasing order, invoke method swap to swap pairs Method bubbleSort receives array reference as parameter Use loop and nested loop to make passes through array If pairs are in decreasing order, invoke method swap to swap pairs

37 Method swap swaps two values in array reference
56 // swap two elements of an array public void swap( int array3[], int first, int second ) { int hold; // temporary holding area for swap 61 hold = array3[ first ]; array3[ first ] = array3[ second ]; array3[ second ] = hold; } 66 67 } // end class BubbleSort BubbleSort.java Lines Method swap swaps two values in array reference Method swap swaps two values in array reference

38 7.8 Dizi Elemanı Aramak: Lineer Arama ve Bölerek Arama
Büyük verilerin içinde istediğiniz elemanı bulma Lineer arama Binary (bölerek) arama

39 7.8 Dizi Elemanı Aramak: Lineer Arama ve Bölerek Arama (Devam.)
Herbir dizi elamanın arama anahtarı ile karşılaştırma Eğer arama anahtarı bulundu ise, dizi indexini döndür Eğer arama anahtarı bulunamadıysa, –1 (değersiz index) dönder. En iyi performansı küçük veya sıralanmamış dizilerde gösterir. Büyük dizilerde verimsiz çalışır.

40 LinearSearch.java Line 11 Declare array of ints
// Fig. 7.11: LinearSearch.java // Linear search of an array. import java.awt.*; import java.awt.event.*; import javax.swing.*; 6 public class LinearSearch extends JApplet implements ActionListener { 8 JLabel enterLabel, resultLabel; JTextField enterField, resultField; int array[]; 12 // set up applet's GUI public void init() { // get content pane and set its layout to FlowLayout Container container = getContentPane(); container.setLayout( new FlowLayout() ); 19 // set up JLabel and JTextField for user input enterLabel = new JLabel( "Enter integer search key" ); container.add( enterLabel ); 23 enterField = new JTextField( 10 ); container.add( enterField ); 26 // register this applet as enterField's action listener enterField.addActionListener( this ); 29 LinearSearch.java Line 11 Declare array of ints Declare array of ints

41 Create 100 ints for array and populate array with even ints
// set up JLabel and JTextField for displaying results resultLabel = new JLabel( "Result" ); container.add( resultLabel ); 33 resultField = new JTextField( 20 ); resultField.setEditable( false ); container.add( resultField ); 37 // create array and populate with even integers 0 to 198 array = new int[ 100 ]; 40 for ( int counter = 0; counter < array.length; counter++ ) array[ counter ] = 2 * counter; 43 } // end method init 45 // search array for specified key value public int linearSearch( int array2[], int key ) { // loop through array elements for ( int counter = 0; counter < array2.length; counter++ ) 51 // if array element equals key value, return location if ( array2[ counter ] == key ) return counter; 55 return -1; // key not found 57 } // end method linearSearch LinearSearch.java Lines Allocate 100 ints for array and populate array with even ints Line 50 Loop through array Lines If array element at index matches search key, return index Create 100 ints for array and populate array with even ints Loop through array If array element at index matches search key, return index

42 Invoked when user presses Enter
59 // obtain user input and call method linearSearch public void actionPerformed( ActionEvent actionEvent ) { // input also can be obtained with enterField.getText() String searchKey = actionEvent.getActionCommand(); 65 // pass array reference to linearSearch; normally, a reference to an // array is passed to a method to search corresponding array object int element = linearSearch( array, Integer.parseInt( searchKey ) ); 69 // display search result if ( element != -1 ) resultField.setText( "Found value in element " + element ); else resultField.setText( "Value not found" ); 75 } // method actionPerformed 77 78 } // end class LinearSearch Invoked when user presses Enter LinearSearch.java Line 61 Invoked when user presses Enter Line 68 Invoke method linearSearch, using array and search key as arguments Invoke method linearSearch, using array and search key as arguments

43 7.8 Dizi Elemanı Aramak: Lineer Arama ve Bölerek Arama (Devam.)
Geniş ve sıralı dizilerde performansı çok iyidir. Her geçişte dizinin yarı kısmını iptal eder. Dizinin orta elemanı ile aramak istediğin veriyi karşılaştır Eğer eşitse Dizi index ini geri dönder. Eğer aranacak eleman daha küçük ise Arama işlemini dizinin ilk yarı kısmında devam et. Eğer aranacak eleman daha büyük ise Arama işlemini dizinin ikinci yarı kısmında devam et. Aramaya devam et Taki... Aramada başarılı olana kadar Bir elemanlı dizin kalmış ve o eleman da aradığın veriye eşit olmasın.

44 BinarySearch.java Line 14 Declare array of ints
// Fig. 7.12: BinarySearch.java // Binary search of an array. import java.awt.*; import java.awt.event.*; import java.text.*; 6 import javax.swing.*; 8 public class BinarySearch extends JApplet implements ActionListener { JLabel enterLabel, resultLabel; JTextField enterField, resultField; JTextArea output; 13 int array[]; String display = ""; 16 // set up applet's GUI public void init() { // get content pane and set its layout to FlowLayout Container container = getContentPane(); container.setLayout( new FlowLayout() ); 23 // set up JLabel and JTextField for user input enterLabel = new JLabel( "Enter integer search key" ); container.add( enterLabel ); 27 enterField = new JTextField( 10 ); container.add( enterField ); 30 BinarySearch.java Line 14 Declare array of ints Declare array of ints

45 Allocate 15 ints for array and populate array with even ints
// register this applet as enterField's action listener enterField.addActionListener( this ); 33 // set up JLabel and JTextField for displaying results resultLabel = new JLabel( "Result" ); container.add( resultLabel ); 37 resultField = new JTextField( 20 ); resultField.setEditable( false ); container.add( resultField ); 41 // set up JTextArea for displaying comparison data output = new JTextArea( 6, 60 ); output.setFont( new Font( "Monospaced", Font.PLAIN, 12 ) ); container.add( output ); 46 // create array and fill with even integers 0 to 28 array = new int[ 15 ]; 49 for ( int counter = 0; counter < array.length; counter++ ) array[ counter ] = 2 * counter; 52 } // end method init 54 // obtain user input and call method binarySearch public void actionPerformed( ActionEvent actionEvent ) { // input also can be obtained with enterField.getText() String searchKey = actionEvent.getActionCommand(); 60 BinarySearch.java Lines Allocate 15 ints for array and populate array with even ints Line 56 Invoked when user presses Enter Allocate 15 ints for array and populate array with even ints Invoked when user presses Enter

46 Invoke method binarySearch, using array and search key as arguments
// initialize display string for new search display = "Portions of array searched\n"; 63 // perform binary search int element = binarySearch( array, Integer.parseInt( searchKey ) ); 66 output.setText( display ); 68 // display search result if ( element != -1 ) resultField.setText( "Found value in element " + element ); else resultField.setText( "Value not found" ); 74 } // end method actionPerformed 76 // method to perform binary search of an array public int binarySearch( int array2[], int key ) { int low = 0; // low element index int high = array2.length - 1; // high element index int middle; // middle element index 83 // loop until low index is greater than high index while ( low <= high ) { middle = ( low + high ) / 2; // determine middle index 87 // display subset of array elements used in this // iteration of binary search loop buildOutput( array2, low, middle, high ); BinarySearch.java Line 65 Invoke method binarySearch, using array and search key as arguments Invoke method binarySearch, using array and search key as arguments

47 If search key matches middle array element, return element index
91 // if key matches middle element, return middle location if ( key == array[ middle ] ) return middle; 95 // if key less than middle element, set new high element else if ( key < array[ middle ] ) high = middle - 1; 99 // key greater than middle element, set new low element else low = middle + 1; 103 } // end while 105 return -1; // key not found 107 } // end method binarySearch 109 // build row of output showing subset of array elements // currently being processed void buildOutput( int array3[], int low, int middle, int high ) { // create 2-digit integer number format DecimalFormat twoDigits = new DecimalFormat( "00" ); 116 If search key matches middle array element, return element index BinarySearch.java Lines If search key matches middle array element, return element index Lines If search key is less than middle array element, repeat search on first array half Lines If search key is greater than middle array element, repeat search on second array half Lines Method build-Output displays array contents being searched If search key is greater than middle array element, repeat search on second array half If search key is less than middle array element, repeat search on first array half Method buildOutput displays array contents being searched

48 BinarySearch.java Line 128 Display an asterisk next to middle element
// loop through array elements for ( int counter = 0; counter < array3.length; counter++ ) { 119 // if counter outside current array subset, append // padding spaces to String display if ( counter < low || counter > high ) display += " "; 124 // if middle element, append element to String display // followed by asterisk (*) to indicate middle element else if ( counter == middle ) display += twoDigits.format( array3[ counter ] ) + "* "; 129 else // append element to String display display += twoDigits.format( array3[ counter ] ) + " "; 132 } // end for 134 display += "\n"; 136 } // end method buildOutput 138 139 } // end class BinarySearch BinarySearch.java Line 128 Display an asterisk next to middle element Display an asterisk next to middle element

49 BinarySearch.java

50 7.9 Çok Boyutlu Diziler Çok Boyutlu Diziler
Satır ve Sutünlardan oluşan Tablolar İki boyutlu dizi İki boyutlu diziyi tanımlama b[2][2] int b[][] = { { 1, 2 }, { 3, 4 } }; 1 ve 2, b[0][0] ve b[0][1] ilk değerleri 3 ve 4, b[1][0] ve b[1][1] ilk değerleri int b[][] = { { 1, 2 }, { 3, 4, 5 } }; satır 0 , 1 ve 2 elementini içerir. satır 1, 3, 4 ve 5 elementini içerir.

51 7.9 Çok Boyutlu Diziler (devam.)
Çok boyutlu dizi oluşturma Dinamik olarak yer alınabilir. 3-by-4 array int b[][]; b = new int[ 3 ][ 4 ]; Satırlar farklı sayıda kolon içerebilirler. int b[][]; b = new int[ 2 ][ ]; // allocate rows b[ 0 ] = new int[ 5 ]; // allocate row 0 b[ 1 ] = new int[ 3 ]; // allocate row 1

52 Fig. 7.13 Two-dimensional array with three rows and four columns.
Sutun 0 Sutun 1 Sutun 2 Sutun 3 Satır 0 a[ 0 ][ 0 ] a[ 0 ][ 1 ] a[ 0 ][ 2 ] a[ 0 ][ 3 ] Satır 1 a[ 1 ][ 0 ] a[ 1 ][ 1 ] a[ 1 ][ 2 ] a[ 1 ][ 3 ] Satır 2 a[ 2 ][ 0 ] a[ 2 ][ 1 ] a[ 2 ][ 2 ] a[ 2 ][ 3 ] Sutun index Satır index Dizi ismi Fig Two-dimensional array with three rows and four columns.

53 Declare array1 with six initializers in two sublists
// Fig. 7.14: InitArray.java // Initializing two-dimensional arrays. import java.awt.Container; import javax.swing.*; 5 public class InitArray extends JApplet { JTextArea outputArea; 8 // set up GUI and initialize applet public void init() { outputArea = new JTextArea(); Container container = getContentPane(); container.add( outputArea ); 15 int array1[][] = { { 1, 2, 3 }, { 4, 5, 6 } }; int array2[][] = { { 1, 2 }, { 3 }, { 4, 5, 6 } }; 18 outputArea.setText( "Values in array1 by row are\n" ); buildOutput( array1 ); 21 outputArea.append( "\nValues in array2 by row are\n" ); buildOutput( array2 ); 24 } // end method init 26 InitArray.java Line 16 Declare array1 with six initializers in two sublists Line 17 Declare array2 with six initializers in three sublists Declare array1 with six initializers in two sublists Declare array2 with six initializers in three sublists

54 Use double-bracket notation to access two-dimensional array values
// append rows and columns of an array to outputArea public void buildOutput( int array[][] ) { // loop through array's rows for ( int row = 0; row < array.length; row++ ) { 32 // loop through columns of current row for ( int column = 0; column < array[ row ].length; column++ ) outputArea.append( array[ row ][ column ] + " " ); 36 outputArea.append( "\n" ); } 39 } // end method buildOutput 41 42 } // end class InitArray array[row].length returns number of columns associated with row subscript InitArray.java Line 34 array[row].length returns number of columns associated with row subscript Line 35 Use double-bracket notation to access two-dimensional array values Use double-bracket notation to access two-dimensional array values

55 Declare grades as 3-by-4 array
// Fig. 7.15: DoubleArray.java // Two-dimensional array example. import java.awt.*; import javax.swing.*; 5 public class DoubleArray extends JApplet { int grades[][] = { { 77, 68, 86, 73 }, { 96, 87, 89, 81 }, { 70, 90, 86, 81 } }; 10 int students, exams; String output; JTextArea outputArea; 14 // initialize fields public void init() { students = grades.length; // number of students exams = grades[ 0 ].length; // number of exams 20 // create JTextArea and attach to applet outputArea = new JTextArea(); Container container = getContentPane(); container.add( outputArea ); 25 Declare grades as 3-by-4 array DoubleArray.java Lines 7-9 Declare grades as 3-by-4 array Lines 7-9 Each row represents a student; each column represents an exam grade Each row represents a student; each column represents an exam grade

56 Determine minimum and maximum for all student
// build output string output = "The array is:\n"; buildString(); 29 // call methods minimum and maximum output += "\n\nLowest grade: " + minimum() + "\nHighest grade: " + maximum() + "\n"; 33 // call method average to calculate each student's average for ( int counter = 0; counter < students; counter++ ) output += "\nAverage for student " + counter + " is " + average( grades[ counter ] ); // pass one row of array grades 38 // change outputArea's display font outputArea.setFont( new Font( "Monospaced", Font.PLAIN, 12 ) ); 41 // place output string in outputArea outputArea.setText( output ); 44 } // end method init 46 // find minimum grade public int minimum() { // assume first element of grades array is smallest int lowGrade = grades[ 0 ][ 0 ]; 52 DoubleArray.java Lines Determine minimum and maximum for all student Lines Determine average for each student Determine minimum and maximum for all student Determine average for each student

57 Use a nested loop to search for lowest grade in series
// loop through rows of grades array for ( int row = 0; row < students; row++ ) 55 // loop through columns of current row for ( int column = 0; column < exams; column++ ) 58 // if grade is less than lowGrade, assign it to lowGrade if ( grades[ row ][ column ] < lowGrade ) lowGrade = grades[ row ][ column ]; 62 return lowGrade; // return lowest grade 64 } // end method minimum 66 // find maximum grade public int maximum() { // assume first element of grades array is largest int highGrade = grades[ 0 ][ 0 ]; 72 // loop through rows of grades array for ( int row = 0; row < students; row++ ) 75 // loop through columns of current row for ( int column = 0; column < exams; column++ ) 78 // if grade is greater than highGrade, assign it to highGrade if ( grades[ row ][ column ] > highGrade ) highGrade = grades[ row ][ column ]; Use a nested loop to search for lowest grade in series DoubleArray.java Lines Use a nested loop to search for lowest grade in series Lines Use a nested loop to search for highest grade in series Use a nested loop to search for highest grade in series

58 Method average takes array of student test results as parameter
82 return highGrade; // return highest grade 84 } // end method maximum 86 // determine average grade for particular student (or set of grades) public double average( int setOfGrades[] ) { int total = 0; // initialize total 91 // sum grades for one student for ( int count = 0; count < setOfGrades.length; count++ ) total += setOfGrades[ count ]; 95 // return average of grades return ( double ) total / setOfGrades.length; 98 } // end method average 100 // build output string public void buildString() { output += " "; // used to align column heads 105 // create column heads for ( int counter = 0; counter < exams; counter++ ) output += "[" + counter + "] "; DoubleArray.java Line 88 Method average takes array of student test results as parameter Lines Calculate sum of array elements Line 97 Divide by number of elements to get average Method average takes array of student test results as parameter Calculate sum of array elements Divide by number of elements to get average

59 109 // create rows/columns of text representing array grades for ( int row = 0; row < students; row++ ) { output += "\ngrades[" + row + "] "; 113 for ( int column = 0; column < exams; column++ ) output += grades[ row ][ column ] + " "; } 117 } // end method buildString 119 120 } // end class DoubleArray DoubleArray.java