Code:
import java.util.Scanner;
/* Class LinkedHashEntry */
class LinkedHashEntry
{
String key;
int value;
LinkedHashEntry next;
/* Constructor */
LinkedHashEntry(String key, int value)
{
this.key = key;
this.value = value;
this.next = null;
}
}
/* Class HashTable */
class HashTable
{
private int TABLE_SIZE;
private int size;
private LinkedHashEntry[] table;
/* Constructor */
public HashTable(int ts)
{
size = 0;
TABLE_SIZE = ts;
table = new LinkedHashEntry[TABLE_SIZE];
for (int i = 0; i < TABLE_SIZE; i++)
table[i] = null;
}
/* Function to get number of key-value pairs */
public int getSize()
{
return size;
}
/* Function to clear hash table */
public void makeEmpty()
{
for (int i = 0; i < TABLE_SIZE; i++)
table[i] = null;
}
/* Function to get value of a key */
public int get(String key)
{
int hash = (myhash( key ) % TABLE_SIZE);
if (table[hash] == null)
return -1;
else
{
LinkedHashEntry entry = table[hash];
while (entry != null && !entry.key.equals(key))
entry = entry.next;
if (entry == null)
return -1;
else
return entry.value;
}
}
/* Function to insert a key value pair */
public void insert(String key, int value)
{
int hash = (myhash( key ) % TABLE_SIZE);
if (table[hash] == null)
table[hash] = new LinkedHashEntry(key, value);
else
{
LinkedHashEntry entry = table[hash];
while (entry.next != null && !entry.key.equals(key))
entry = entry.next;
if (entry.key.equals(key))
entry.value = value;
else
entry.next = new LinkedHashEntry(key, value);
}
size++;
}
public void remove(String key)
{
int hash = (myhash( key ) % TABLE_SIZE);
if (table[hash] != null)
{
LinkedHashEntry prevEntry = null;
LinkedHashEntry entry = table[hash];
while (entry.next != null && !entry.key.equals(key))
{
prevEntry = entry;
entry = entry.next;
}
if (entry.key.equals(key))
{
if (prevEntry == null)
table[hash] = entry.next;
else
prevEntry.next = entry.next;
size--;
}
}
}
/* Function myhash which gives a hash value for a given string */
private int myhash(String x )
{
int hashVal = x.hashCode( );
hashVal %= TABLE_SIZE;
if (hashVal < 0)
hashVal += TABLE_SIZE;
return hashVal;
}
/* Function to print hash table */
public void printHashTable()
{
for (int i = 0; i < TABLE_SIZE; i++)
{
System.out.print("\nBucket "+ (i + 1) +" : ");
LinkedHashEntry entry = table[i];
while (entry != null)
{
System.out.print(entry.value +" ");
entry = entry.next;
}
}
}
}
/* Class HashTablesChainingListHeadsTest */
public class HashTablesChainingListHeadsTest
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
System.out.println("Hash Table Test\n\n");
System.out.println("Enter size");
/* Make object of HashTable */
HashTable ht = new HashTable(scan.nextInt() );
char ch;
/* Perform HashTable operations */
do
{
System.out.println("\nHash Table Operations\n");
System.out.println("1. insert ");
System.out.println("2. remove");
System.out.println("3. get");
System.out.println("4. clear");
System.out.println("5. size");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println("Enter key and value");
ht.insert(scan.next(), scan.nextInt() );
break;
case 2 :
System.out.println("Enter key");
ht.remove( scan.next() );
break;
case 3 :
System.out.println("Enter key");
System.out.println("Value = "+ ht.get( scan.next() ));
break;
case 4 :
ht.makeEmpty();
System.out.println("Hash Table Cleared\n");
break;
case 5 :
System.out.println("Size = "+ ht.getSize() );
break;
default :
System.out.println("Wrong Entry \n ");
break;
}
/* Display hash table */
ht.printHashTable();
System.out.println("\nDo you want to continue (Type y or n) \n");
ch = scan.next().charAt(0);
} while (ch == 'Y'|| ch == 'y');
}
}
Output:
Hash Table Test
Enter size
5
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
water 100
Bucket 1 :
Bucket 2 :
Bucket 3 : 100
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
apple 5
Bucket 1 : 5
Bucket 2 :
Bucket 3 : 100
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
mango 24
Bucket 1 : 5 24
Bucket 2 :
Bucket 3 : 100
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
guava 13
Bucket 1 : 5 24
Bucket 2 :
Bucket 3 : 100 13
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
pineapple 17
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100 13
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
1
Enter key and value
strawberry 37
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100 13
Bucket 4 : 37
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
3
Enter key
apple
Value = 5
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100 13
Bucket 4 : 37
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
3
Enter key
mango
Value = 24
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100 13
Bucket 4 : 37
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
2
Enter key
guava
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100
Bucket 4 : 37
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
5
Size = 5
Bucket 1 : 5 24
Bucket 2 : 17
Bucket 3 : 100
Bucket 4 : 37
Bucket 5 :
Do you want to continue (Type y or n)
y
Hash Table Operations
1. insert
2. remove
3. get
4. clear
5. size
4
Hash Table Cleared
Bucket 1 :
Bucket 2 :
Bucket 3 :
Bucket 4 :
Bucket 5 :
Do you want to continue (Type y or n)
n
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