src.java.com.ctc.wstx.util.InternCache Maven / Gradle / Ivy
package com.ctc.wstx.util;
import java.util.HashMap;
/**
* Singleton class that implements "fast intern" functionality, essentially
* adding a layer that caches Strings that have been previously intern()ed,
* but that probably shouldn't be added to symbol tables.
* This is usually used by improving intern()ing of things like namespace
* URIs.
*
* Note: that this class extends {@link HashMap} is an implementation
* detail -- no code should ever directly call Map methods.
*/
public final class InternCache
extends HashMap
{
/**
* Let's create cache big enough to usually have enough space for
* all entries... (assuming NS URIs only)
*/
private final static int DEFAULT_SIZE = 64;
private final static InternCache sInstance = new InternCache();
private InternCache() {
/* Let's also try to seriously minimize collisions... since
* collisions are likely to be more costly here, with longer
* Strings; so let's use 2/3 ratio (67%) instead of default
* (75%)
*/
super(DEFAULT_SIZE, 0.6666f);
}
public static InternCache getInstance() {
return sInstance;
}
public synchronized String intern(String input) {
String result = (String) get(input);
if (result == null) {
result = input.intern();
put(result, result);
}
return result;
}
}