The Java language has a list of reserved keywords that can't be used as identifiers in Java programs. An identifier is a unique name that you give to an element within a program, such as a field or method. Some of the Java keywords are rarely used and others are very common. Here is the list:

abstract	continue	for	new	switch
assert	default	goto	package	synchronized
boolean	do	if	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

Additionally, there are 3 reserved literals that can't be used as identifiers: true, false and null. Most of the keywords listed here will be discussed the first time they appear in the code examples of the tutorials to come. For now, just bear in mind that the Java keywords and reserved literals can't be used as identifiers.

The next tutorial lists all the primitive types of the Java language.