When you write String::toUpperCase, Java binds each element of the stream (String object) to the toUpperCase() method. This means String::toUpperCase is interpreted as s -> s.toUpperCase() , where ...

8 guidelines for writing reusable Java code. Define the rules for your code; Document your APIs; Follow standard code naming conventions; Write cohesive classes and methods ...

According to the Java Enhancement Proposal 445: …these changes allow us to write Hello, World! with no access modifiers, no static modifiers, and no String[] parameter, so the introduction of these ...