Java follows C++ to some degree, which carries the benefit of it being familiarto many programmers. This section describes the essential features of Java andpoints out where the language diverges from its ancestors C and C++.2.1.1 Primitive Data Other than the primitive data types discussed here, everything in Java is anobject. Even the primitive data types can be encapsulated inside librarysuppliedobjects if required. Java follows C and C++ fairly closely in its set ofbasic data types, with a couple of minor exceptions. There are only threegroups of primitive data types, namely, numeric types, Boolean types, andarrays.
Integer numeric types are 8-bit byte, 16-bit short, 32-bit int, and 64-bit long.The 8-bit byte data type in Java has replaced the old C and C++ char datatype. Java places a different interpretation on the char data type, as discussedbelow.There is no unsigned type specifier for integer data types in Java.Real numeric types are 32-bit float and 64-bit double. Real numeric typesand their arithmetic operations are as defined by the IEEE 754 specification. Afloating point literal value, like 23.79, is considered double by default; youmust explicitly cast it to float if you wish to assign it to a float variable.Character Data TypesJava language character data is a departure from traditional C. Java’s char datatype defines a sixteen-bit Unicode character. Unicode characters are unsigned16-bit values that define character codes in the range 0 through 65,535. If youwrite a declaration such aschar myChar = ‘Q’;you get a Unicode (16-bit unsigned value) type that’s initialized to the Unicodevalue of the character Q. By adopting the Unicode character set standard for itscharacter data type, Java language applications are amenable tointernationalization and localization, greatly expanding the market for worldwideapplications.
Java has added a boolean data type as a primitive type, tacitly ratifyingexisting C and C++ programming practice, where developers define keywordsfor TRUE and FALSE or YES and NO or similar constructs. A Java booleanvariable assumes the value true or false. A Java boolean is a distinct datatype; unlike common C practice, a Java boolean type can’t be converted toany numeric type.
Integer numeric types are 8-bit byte, 16-bit short, 32-bit int, and 64-bit long.The 8-bit byte data type in Java has replaced the old C and C++ char datatype. Java places a different interpretation on the char data type, as discussedbelow.There is no unsigned type specifier for integer data types in Java.Real numeric types are 32-bit float and 64-bit double. Real numeric typesand their arithmetic operations are as defined by the IEEE 754 specification. Afloating point literal value, like 23.79, is considered double by default; youmust explicitly cast it to float if you wish to assign it to a float variable.Character Data TypesJava language character data is a departure from traditional C. Java’s char datatype defines a sixteen-bit Unicode character. Unicode characters are unsigned16-bit values that define character codes in the range 0 through 65,535. If youwrite a declaration such aschar myChar = ‘Q’;you get a Unicode (16-bit unsigned value) type that’s initialized to the Unicodevalue of the character Q. By adopting the Unicode character set standard for itscharacter data type, Java language applications are amenable tointernationalization and localization, greatly expanding the market for worldwideapplications.
Java has added a boolean data type as a primitive type, tacitly ratifyingexisting C and C++ programming practice, where developers define keywordsfor TRUE and FALSE or YES and NO or similar constructs. A Java booleanvariable assumes the value true or false. A Java boolean is a distinct datatype; unlike common C practice, a Java boolean type can’t be converted toany numeric type.
