What is current status of Oracle Java HotSpot VM performance options (+UseStringCache, +UseCompressedStrings, +OptimizeStringConcat)

To check defaults use

java -XX:+PrintFlagsFinal

To find exactly what you want you can

java -XX:+PrintFlagsFinal | grep UseCompressedStrings

I know that -XX:+UseCompressedStrings was dropped in Java 7 on the basis it was too hard to support.

For Java 7 update 40

$ java -XX:+PrintFlagsFinal 2>&1 | grep UseStringCache
     bool UseStringCache                            = false           {product}           
$ java -XX:+PrintFlagsFinal 2>&1 | grep OptimizeStringConcat
     bool OptimizeStringConcat                      = true            {C2 product}  

Considering String performance, have a look at the -XX:+PrintStringTableStatistics and -XX:StringTableSize=. Java 7 comes with nice features that allow tuning of String cache when using the interned Strings. This way you can optimize the String cache size.

And, a related String Performance Q/A: Java GC tuning for strings