public class DTMStringPool extends Object
DTMStringPool is an "interning" mechanism for strings. It will create a stable 1:1 mapping between a set of string values and a set of integer index values, so the integers can be used to reliably and uniquely identify (and when necessary retrieve) the strings.
Design Priorities:
Implementation detail: A standard Hashtable is relatively inefficient when looking up primitive int values, especially when we're already maintaining an int-to-string vector. So I'm maintaining a simple hash chain within this class.
NOTE: There is nothing in the code that has a real dependency upon String. It would work with any object type that implements reliable .hashCode() and .equals() operations. The API enforces Strings because it's safer that way, but this could trivially be turned into a general ObjectPool if one was needed.
Status: Passed basic test in main().
Modifier and Type | Field and Description |
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static int |
NULL |
Constructor and Description |
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DTMStringPool() |
DTMStringPool(int chainSize)
Create a DTMStringPool using the given chain size
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Modifier and Type | Method and Description |
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String |
indexToString(int i) |
static void |
main(String[] args)
Command-line unit test driver.
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void |
removeAllElements() |
int |
stringToIndex(String s) |
public static final int NULL
public DTMStringPool(int chainSize)
chainSize
- The size of the hash chain vectorpublic DTMStringPool()
public void removeAllElements()
public String indexToString(int i) throws ArrayIndexOutOfBoundsException
ArrayIndexOutOfBoundsException
- if index doesn't map to a string.public int stringToIndex(String s)
public static void main(String[] args)
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