What's are Java keywords?

keywords are reserved identifiers. Predefined identifiers in Java language, that is, they are used in a program exclusively the way already defined by Java. All the keywords are in lowercase. Java compiler enforces this predefined usage. Incorrect usage of keywords if flagged by the compiler and results in compilation errors.

These are the keywords currently defined and used in Java:

abstract	default	if	private	this
assert	do	implements	protected	throw
boolean	double	import	public	throws
break	else	instanceof	return	transient
byte	enum	int	short	try
case	extends	interface	static	void
catch	final	long	strictfp	volatile
char	finally	native	super	while
class	float	new	switch
continue	for	package	synchronised

Additionally, Java has two reserved keywords which are currently not in use:
const goto

Note: you can't use keywords either used or just reserved by Java.