CaseBlindHashMap - a HashMap extension, using Strings as key values.
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*/
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();
}
}
}
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