(See related pages)
|
|
|
| • A variable is a memory location in which to store a value. • A variable has a name and a data type. • A variable must be declared before we can assign a value to it. • There are six numerical data types in Java: byte, short, int, long, float, and double. • Object names are synonymous with variables whose contents are memory addresses. • Numerical data types are called primitive data types, and objects are called reference data types. • Precedence rules determine the order of evaluating arithemetic expressions. • Symbolic constants hold values just as variables do, but we cannot change their values. • The standard classes introduced in this chapter are: Math InputStream GregorianCalendar InputStreamReader DecimalFormat BufferedReader PrintStream IOException Integer, Double, etc. • We use methods from the wrapper classes Integer, Double, and others to convert an input string to a numerical value. • System.out is used to output multiple lines of text to the standard output window. • System.in is used to input a stream of bytes. We associate a BufferedReader object to System.in (with an intermediate InputStreamReader) to input one line of text at at time. • The Math class contains many class methods for mathematical functions. • The GregorianCalendar class is used in the manipulation of calendar information. • The DecimalFormat class is used to format numerical data. • (Optional) Twos complement format is used for storing integers, and floating-pointing format is used for storing real numbers. |