Strings and Regular Expressions - The Java Programming Language - page 460

for (i = 0; i < tableSize; i++)
if (table[i] == unique)
return i;
// it's not there--add it in
table[i] = unique;
tableSize++;
return i;
}
All the strings stored in the table array are the result of an intern invoc-
ation. The table is searched for a string that was the result of an intern
invocation on another string that had the same contents as the key . If
this string is found, the search is finished. If not, we add the unique
representative of the key at the end. Dealing with the results of intern
makes comparing object references equivalent to comparing string con-
tents, but much faster.
Any two strings with the same contents are guaranteed to have the
same hash codethe String class overrides Object.hashCode although two
different strings might also have the same hash code. Hash codes
are useful for hashtables, such as the HashMap class in java.util see
" HashMap " on page 590 .
13.2.4. Making Related Strings
Several String methods return new strings that are like the old one but
with a specified modification. New strings are returned because String
objects are immutable. You could extract delimited substrings from an-
other string by using a method like this one:
public static String delimitedString(
String from, char start, char end)
{
int startPos = from.indexOf(start);
int endPos = from.lastIndexOf(end);