How to create a Hash Table

by Sanju 2010-03-04 09:59:50

How to create a Hash Table

Hash table is generally used in searching applications. Hash table increases the search efficiency by creating a key corresponding to the values in the table.

// Create a hash table
Map map = new HashMap();
map = new TreeMap(); // sorted map

// Add key/value pairs to the map
map.put("x", new Integer(1));
map.put("y", new Integer(2));
map.put("z", new Integer(3));

// Get number of entries in map
int size = map.size(); // 2

// Adding an entry whose key exists in the map causes
// the new value to replace the old value
Object oldValue = map.put("x", new Integer(9)); // 1

// Remove an entry from the map and
// return the value of the removed entry
oldValue = map.remove("c"); // 3

// Iterate over all keys in the table
Iterator it = map.keySet().iterator();
while (it.hasNext()) {
// Retrieve key
Object key = it.next();
}

// Iterate over all values in table
it = map.values().iterator();
while (it.hasNext()) {
// Get value
Object value = it.next();
}

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