is there a lambda function that cannot be a method reference

Question

in a lecture I gave at my company I suggested converting any complex lambda to a method reference (more readable and better debug and testing) and was asked if it is always possible.

I searched and could not find a lambda that cannot be replaced with method reference.

am I right? (lambda can always be replaced with method reference)

Answer 1

Method reference cannot capture variables. So a capturing lambda cannot be directly converted to a method reference. For example,

int x = 1;
numbers.replaceAll(n -> n + x);

In some cases, if only one variable is captured, it might be possible to convert lambda to a method reference on the captured variable. For example,

String greeting = "Hello, ";

people.replaceAll(name -> greeting + name);

Can be converted to method reference as

people.replaceAll(greeting::concat);