useful Java library functions

Question

I've recently come across a couple library functions that are really useful and I wanted to share them, but I also wanted you to tell me some functions that you believe everyone should know.

boolean equalsIgnorecase(String other)
works just like equals, but it iGnoReS caSeS (would have never told by its name, huh?)

String toBinaryString(int i) returns a String made of the binary value of your int

boolean endsWith(String s), true if your String ends with whatever is s

Answer 1

I think Collections are worth to have a close look at them... very useful ;)