Some notes on writing a Java software program (pt7)

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There are two kinds of types in the Java programming language: primitive types and reference types. There are, correspondingly, two kinds of data values that can be stored in variables, passed as arguments, returned by methods, and operated on: primitive values and reference values.There is also a special null type, the type of the expression null, which has no name.Because the null type has no name, it is impossible to declare a variable of the null type or to cast to the null type.(Early-plugs insertion point. A few seconds of silence in audiovisual.)The null reference is the only possible value of an expression of null type.The null reference can always be assigned or cast to any reference type.In practice, the programmer can ignore the null type and just pretend that null is merely a special literal that can be of any reference type.The primitive types are boolean, byte, short, int, long, char, float, and double.Primitive values do not share state with other primitive values.The numeric types are the integral types and the floating-point types.The boolean type has exactly two values: true and false.Integer Operations. The Java programming language provides a number of operators that act on integral values.The comparison operators, which result in a value of type boolean: The numerical comparison operators, The numerical equality operators.The numerical operators, which result in a value of type int or long: The unary plus and minus operators, The multiplicative operators, The additive operators, the prefix and postfix increment operators, the prefix and postfix decrement operators, The signed and unsigned shift operators, The bitwise complement operator, The integer bitwise operators.The conditional operator.The cast operator , which can convert from an integral value to a value of any specified numeric type.The string concatenation operator, which, when given a String operand and an integral operand, will convert the integral operand to a String (the decimal form of a byte, short, int, or long operand, or the character of a char operand), and then produce a newly created String that is the concatenation of the two strings.Other useful constructors, methods, and constants are predefined in the classes Byte, Short, Integer, Long, and Character.Any value of any integral type may be cast to or from any numeric type. There are no casts between integral types and the type boolean.

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