substring

If you're doing a substring match, then use a substring function.

How about substring searching: Boyer- Moore searches backwards, Rabin Karp computes hashes while others simulate automata.

In Bioinformatics, this is known as the Smith-Waterman algorithm [2] and the result would satisfy the requirements of fuzzy substring matching.

Read in mb of data in a String, substring a couple kb out, and tada!

From the start, you're taught that Strings are immutable objects, so you probably understand that `.substring()` produces a new instance object.

This had some harmful effects for those expecting substring() would always share the underlying char[].

Is it really more common that people do substring and expect the rest to be thrown away than the other way around?

Here is an explanation of the change to `substring()`[0] and why it was done.

Without prior knowledge of the implementation, why would you expect a reference to a substring to hold the entire original string in memory?

You can't just deprecate substring() which is a function that is used in what 90% of the millions of Java applications around the world.

I'd hate to be writing a grammar every time I want to do a substring match.

I definitely think it is more common for a programmer to expect that if they make a substring, and never reference the original string again, only the substring would remain in memory after GC.

The description in the Java 7 API for substring is "Returns a new string that is a substring of this string." That does not suggest any sharing with the parent string; it says "new string".

This is why the article's code example yields such a huge difference in memory usage in Java 6 vs Java 7; it is effectively a sort of "anti-pattern" when used against the new `substring()` method.

In this respect, the Java/Oracle folks likely decided that optimizing for the "parsing/tokenization" use case (where you make lots of substrings from a large original string and thus it makes sense to use the same underlying character array) was more novel and less frequent than the use case of "just pulling a small substring from a much larger one and then discarding the large one."

Substring optimization for small but not larger strings.