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The Java Developers Almanac 1.4Order this book from Amazon. |
e355. Creating a Hash TableA hash table, or map, holds key/value pairs.// Create a hash table Map map = new HashMap(); // hash table map = new TreeMap(); // sorted map // Add key/value pairs to the map map.put("a", new Integer(1)); map.put("b", new Integer(2)); map.put("c", 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("a", 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 the keys in the map Iterator it = map.keySet().iterator(); while (it.hasNext()) { // Get key Object key = it.next(); } // Iterate over the values in the map it = map.values().iterator(); while (it.hasNext()) { // Get value Object value = it.next(); }
e357. Automatically Removing an Unreferenced Element from a Hash Table
© 2002 Addison-Wesley. |