Java tutorial
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Except as contained in this notice, the name of Stanford University shall not be used in advertising or otherwise to promote the sale, use or other dealings in this Software without prior written authorization from Stanford University. */ import java.util.HashMap; import java.util.Iterator; import java.util.Set; /** * CaseBlindHashMap - a HashMap extension, using <code>String</code>s as key * values. * <p> * Internally, keys are case insensitive: <code>ABC</code> = <code>abc</code>. * <p> * Two methods have been added to facilitate working with Sets of key strings. * See <code>stringKeySet()</code> and <code>stringKeyIterator()</code>. */ public class CaseBlindHashMap extends HashMap { /** * Constructors */ public CaseBlindHashMap() { super(); } public CaseBlindHashMap(CaseBlindHashMap map) { super(map); } public CaseBlindHashMap(int initCap) { super(initCap); } public CaseBlindHashMap(int initCap, float loadFactor) { super(initCap, loadFactor); } /* * Extensions */ /** * Get the set of keys contained in this map. Keys values are returned as * simple <code>String</code>s (not the <code>CaseBlindString</code>s * used internally). * <p> * This is accopmlished by making a copy of the original map - modifications * made to this copy are not reflected in the original. * * @return The set of keys */ public Set stringKeySet() { Iterator iterator = super.keySet().iterator(); HashMap stringKeys = new HashMap(); while (iterator.hasNext()) { String key = ((CaseBlindString) iterator.next()).toString(); stringKeys.put(key, get(key)); } return stringKeys.keySet(); } /** * Get an Iterator to the String based key set * * @return An iterator to the key set */ public Iterator stringKeyIterator() { return stringKeySet().iterator(); } /* * Overridden HashMap methods */ /** * Does the map contain this key? * * @param key * The key to look up * @return true If the key is present in the map */ public boolean containsKey(String key) { return super.containsKey(new CaseBlindString(key)); } /** * Fetch a value by name - null keys are not supported * * @param key * The key to look up * @return The associated value object */ public Object get(String key) { return super.get(new CaseBlindString(key)); } /** * Add the key/value pair to the map - null values are not supported * * @param key * The key name * @param value * The object to store */ public void put(String key, Object value) { super.put(new CaseBlindString(key), value); } /** * Remove a key/value pair from this map * * @param key * Non-null key to remove */ public void remove(String key) { if (key == null) { throw new UnsupportedOperationException("null key"); } super.remove(new CaseBlindString(key)); } /** * A crude, case insensitive string - used internally to represent key values. * Preserve the originl case, but compare for equality in a case blind * fashion. */ public static class CaseBlindString { String string; /** * Constructors */ private CaseBlindString() { } public CaseBlindString(String string) { this.string = string; } /** * Fetch the original string * * @return The original string */ public String toString() { return string; } /** * Case insensitive compare * * @return True if the two strings match */ public boolean equals(Object object) { if (string == null) { return string == null; } return string.equalsIgnoreCase(((CaseBlindString) object).toString()); } /** * Get a hash code for this case insensitive string * * @return Hash code value */ public int hashCode() { if (string == null) { return "null".hashCode(); } return string.toUpperCase().hashCode(); } } }