double expressions variables and constants are used in expressions to define new values and to modify variables in this sectionwe discuss how expressions work in java in more detail expressions involve the use of literalsvariablesand operators since we have already discussed variableslet us briefly focus on literals and then discuss operators in some detail literals literal is any "constantvalue that can be used in an assignment or other expression java allows the following kinds of literalsthe null object reference (this is the only object literaland it is defined to be from the general object classbooleantrue and false integerthe default for an integer like or - is that it is of type intwhich is -bit integer long integer literal must end with an "lor " ,for example or - land defines -bit integer floating pointthe default for floatingnumberssuch as and is that they are double to specify that literal is floatit must end with an "for " floating-point literals in exponential notation are also allowedsuch as or the base is assumed to be characterin javacharacter constants are assumed to be taken from the unicode alphabet typicallya character is defined as an individual symbol enclosed in single quotes for example'aand '?are character constants in additionjava defines the following special character constants'\ (newline'\ (tab'\ (backspace'\ (return