For variables to be used in programming, they must first be declared and initialized . Variable declaration consists of two parts : a data type and an identifier. Variable types are either primitives or references to objects. After it has been declared, a value is introduced to a scope, which may then be stored in a variable, provided it is within the limits of the variable's type. Furthermore, expressions can be utilized to perform calculations and may also be used to store values.
Expressions make use of operators, which are the symbols (or group of symbols) a program uses to indicate a specific operation to perform (such as addition, multiplication, or division). Operators are evaluated in order of precedence, and from either left to right or right to left, depending on their associativity.
Control-flow statements, such as branching statements and loops , direct program execution. In addition, exception handlers are used to control the flow of program execution when an exception is thrown. The exception mechanism is a general-purpose error processing mechanism, which detects errors in code by throwing objects that disrupt the normal flow of program execution.