Hash Table - Using a Separate Class, and also Objects

And with Tie-breaking

This is the full example, including:

• A separate class for the hash table.
• GUI interface.
• A hash table of objects, not just primitives.
• And takes into account tie-breaking.

     

 

/Users/adelaide/Public/Netbeans - All JSR Projects/Hashing 2012/src/hashing2012package/HashGUI.java

  1 package hashing2012package;
  2 
  3 /**
  4  *
  5  * @author John Rayworth
  6  */
  7 public class HashGUI extends javax.swing.JFrame {
  8 
  9     LibraryBookHashTable myHashTable;
 10 
 11     public HashGUI() {
 12         initComponents();
 13         myHashTable = new LibraryBookHashTable(5000);
 14     }
 15                    
247 
248     private void addButtonMouseReleased(java.awt.event.MouseEvent evt) {                                        
249         
250         LibraryBook book = new LibraryBook(bookTitleTF.getText(), Double.parseDouble(DDNumberTF.getText()));
251         if(myHashTable.addToHashTable(book)){//Note here a boolean is returned if the hashtable is not full.
252             bookTitleTF.setText("");
253             DDNumberTF.setText("");
254         }else{
255             bookTitleTF.setText("Sorry, hash table full.");
256             DDNumberTF.setText("Sorry, hash table full.");
257         }
254         
255     }                                       
256 
257     private void searchButtonMouseReleased(java.awt.event.MouseEvent evt) {                                           
258         
259         LibraryBook bookResult = new LibraryBook();     
260         bookResult = myHashTable.findName(bookSearchTF.getText());
261         
262         if(bookResult == null){
263             DDNumberResultTF.setText("No book by that name.");
264         }else{
265             DDNumberResultTF.setText(bookResult.getDDNumber()+"");
266         }
267         
268     } 

/Users/adelaide/Public/Netbeans - All JSR Projects/Hashing 2012/src/hashing2012package/LibraryBookHashTable.java

 1 package hashing2012package;
 2 
 3 /**
 4  *
 5  * @author John Rayworth
 6  */
 7 public class LibraryBookHashTable {
 8 
 9     private LibraryBook[] hashArray;
10     private int hashTableLength;
11     private boolean isFull = false;
12 
13     public LibraryBookHashTable(int hashTableLength) {
14         this.hashTableLength = hashTableLength;
15         hashArray = new LibraryBook[hashTableLength];
16         for (int i = 0; i < hashTableLength; i++) {
17             hashArray[i] = new LibraryBook();
18         }
19     }
20     
21     private boolean isFull(){
22         return isFull;
23     }
24 
25     public boolean addToHashTable(LibraryBook bookToHash){
26 
27         int total = 0;
28         String nameToHash = bookToHash.getBookTitle();
29         for (int i = 0; i < nameToHash.length(); i++) {
30             total += nameToHash.charAt(i);
31         }
32         int hashValue = total % hashTableLength;
33         int startingHashValue = hashValue;
34         while (!hashArray[hashValue].getBookTitle().equals("not set yet") && !isFull()) {
35             hashValue++;
36             if (hashValue == hashArray.length) {
37                 hashValue = 0;
38             }
39             if(hashValue + 1 == startingHashValue){//The way to know if the hash table is full.
40                 isFull = true;
41             }
42         }
43         System.out.println(hashValue);
44         if(!isFull()){
45             hashArray[hashValue] = bookToHash;
46             return true;
47         }
48         else{
49             return false;//not added because full
50         }
51     }
37 
38     public LibraryBook findName(String stringToFind){
39         int total = 0;
40         for (int i = 0; i < stringToFind.length(); i++) {
41             total += stringToFind.charAt(i);
42         }
43         int hashValue = total % hashTableLength;
44         
45         if (!hashArray[hashValue].getBookTitle().equals(stringToFind)) {
46             int startingHashValue = hashValue;
47             while (!hashArray[hashValue].getBookTitle().equals(stringToFind)) {
48                 hashValue++;
49                 if (hashValue == hashArray.length) {
50                     hashValue = 0;
51                 }
52                 if(hashValue == startingHashValue){
53                     return null;
54                 }
55             }
56         }
57         return hashArray[hashValue];    
58     }
59 }
60 
61 

Scorll down if you think you need to see the LibraryBook template class.

 

 

 

 

 

/Users/adelaide/Public/Netbeans - All JSR Projects/Hashing 2012/src/hashing2012package/LibraryBook.java

 1 package hashing2012package;
 2 
 3 /**
 4  *
 5  * @author John Rayworth
 6  */
 7 public class LibraryBook {
 8     
 9     
10    private String bookTitle = "not set yet";
11    private double DDNumber = -999.999;
12     
13    public LibraryBook(){
14        
15    }
16    
17    public LibraryBook(String bookTitle, double DDNumber){
18        this.bookTitle = bookTitle;
19        this.DDNumber = DDNumber;
20    }
21    
22    public String getBookTitle(){
23        return bookTitle;
24    }
25    
26    public double getDDNumber(){
27        return DDNumber;
28    }
29    
30    public void setBookTitle(String bookTitle){
31        this.bookTitle = bookTitle;
32    }
33    
34    public void setDDNumber(double DDNumber){
35        this.DDNumber = DDNumber;
36    }
37  
38 }
39 
40