This description introduces a formal notation known as a template that we use occasionally
to specify the format of Java constructs. We put within angle brackets (< >)
a construct that we have already defined, to indicate that we can use any instance of
that construct where specified. In this case, represents an
expression that has a boolean value, such as one involving a comparison operation,
and < block statements> represents a sequence of Java statements. It is possible to
make formal definitions of and , but
we refrain from going into that level of detail. The meaning of an if statement is selfexplanatory:
the statement(s) in the block are to be executed if and only if the boolean
expression is true. The if-else statement: