What's the difference between instance method reference types in Java 8?

Question

So Java 8 introduces method references and the docs describe the four types.

My question is what\'s the difference between the two instance types?

Answer 1

1. myString::charAt would take an int and return a char, and might be used for any lambda that works that way. It translates, essentially, to index -> myString.charAt(index).

2. String::length would take a String and return an int. It translates, essentially, to string -> string.length().

3. String::charAt would translate to (string, index) -> string.charAt(index).