https://youtu.be/rxSt7M9kw7Y
UnqualifiedMethodIdentifier is used when a method invocation expression refers to a method by its simple name.51 character sequences, formed from ASCII characters, are reserved for use as keywords and cannot be used as identifiers. Another 16 character sequences, also formed from ASCII characters, may be interpreted as keywords or as other tokens, depending on the context in which they appear.(Early-plugs insertion point. A few seconds of silence in audiovisual.)Reserved keywords are abstract, continue, for, new, switch, assert, default, if, package, synchronized, boolean, do, goto, private, this, break, double, implements, protected, throw, byte, else, import, public, throws, case, enum, instanceof, return, transient, catch, extends, int, short, try, char, final, interface, static, void, class, finally, long, strictfp, volatile, const, float, native, super, while, _ (underscore).Contextual keywords are exports, opens, requires, uses, module, permits, sealed, var, non-sealed, provides, to, with, open, record, transitive, yield.The keywords const and goto are reserved, even though they are not currently used.The keyword strictfp is obsolete and should not be used in new code.The keyword _ (underscore) is reserved for possible future use in parameter declarations.true and false are not keywords, but rather boolean literals.null is not a keyword, but rather the null literal.A literal is the source code representation of a value of a primitive type, the String type, or the null type.In the Java programming language, a literal is an integer literal, a floating-point literal, a boolean literal, a character literal, a string literal, a text block, or a null literal.An integer literal may be expressed in decimal (base 10), hexadecimal (base 16), octal (base 8), or binary (base 2).In the Java programming language, integer literal can be a decimal integer literal, a hex integer literal, an octal integer literal, or a binary integer literal.An integer literal is of type long if it is suffixed with an ASCII letter L or l (ell);otherwise it is of type int. The suffix L is preferred, because the letter l (ell) is often hard to distinguish from the digit 1 (one).