OCA JAVA - 3 Programming with Java Operators

OCA JAVA - 3 Programming with Java Operators

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  3. Programming with JavaOperators • Understanding Fundamentals Operators • Understanding Operator Precedence By Fernando Gil Date: Jan 2015 Version: 1.0 Based in the book OCA Java SE 7 Programmer I Study Guide (Examn 1Z0-803)
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  1. Understanding Fundamental Operators •Java operators are used to return a result from an expression using one, two, or three operands • Operands are the values placed to the right or left side of the operators • Prefix/postfix – increment/decrement operators use one operand • The conditional ternary operator (?:) uses three operands • All other operators use two operands
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  Assignment Operators • Assignmentoperators are used to assign values to variables • The assignment operator by itself is the equal sign • At it simplest, the assignment operator moves valid literals into variables • Assignment operators cause compiler errors when the literals are not valid for the variable to which they are assigned
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  Compound Assignment Operators • Compoundassignment operators provide a shorter syntax for assigning the result of an arithmetic or bitwise operator • They perform the operation on the two operands before assigning the result to the first operand • There are 11 compound assignment operators • While the use of compound assignment operators cuts down on keystrokes, it is generally good practice to use the longhand approach since the code is clearly more readable
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  Operator Function += Assignsthe result of the addition - = Assigns the result of the subtraction *= Assigns the result of the multiplication /= Assigns the result of the division %= Assigns the remainder of the division &= Assigns the result of the logical AND |= Assigns the result of the logical OR ^= Assigns the result of the logical XOR <<= Assigns the result of the signed left bit shift >>= Assigns the result of the signed right bit shift >>>= Assigns the result of the unsigned right bit shift
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  Basic Arithmetic Operators OperatorFunction + Addition (sum) operator - Subtraction (difference) operator * Multiplication (product) operator / Division (quotient) operator % Modulus (remainder) operator int totalCannonBalls = greyCannonBalls + blackCannonBalls;
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  Prefix and PostfixOperators Operator Function ++ X Prefix increment operator -- X Prefix decrement operator X++ Postfix increment operator X -- Postfix decrement operator • The execution of prefix operators occurs on the operand prior to the evaluation of the whole expression • The execution of postfix operators occurs after the expression has been evaluated
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  Basic Relational Operators OperatorFunction < Less than operator <= Less than or equal to operator > Greater than operator >= Greater than or equal to operator • Those operators are used to compare integers, floating points, and characters • When the expression used with the relational operators is true, the Boolean value of true is returned; otherwise, false is returned
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  Equality Operators Operator Function ==Equal to operator != Not equal to operator • Relational operators that directly compare the equality of primitives and object reference variables are considered equality operators
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  Logical Operators Operator Function &&Logical AND to operator || Logical OR operator • Logical (conditional) operators evaluate a pair of Boolean operands. If both values of the operands have a value of true, then a value of true is returned • To return true with the AND operator both operands would need to be true. • To return true with the OR operator only one operand needs to be true
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  Logical Negation Operator OperatorFunction ! Logical negation operator • It is also known as the inversion operator or Boolean invert operator, and it returns the opposite of a Boolean value • Expect to see the logical negation operator used in conjunction with any method or expression that return a Boolean value • This operator cannot be used on a non-Boolean value
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  2. Understanding Operator Precedence •Operator precedence is the order in which operators will be evaluated when several operators are included in an expression • Operators with a higher precedence are evaluated before operators with a lower precedence • Operator precedence can be overridden using parentheses • When multiple sets of parentheses are present, the innermost set is evaluated first
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  Precedence Order • Whentwo operators share an operand, the operator with the higher precedence goes first. For example: 1 + 2 * 3 is treated as 1 + (2 * 3) whereas 1 * 2 + 3 is treated as (1 * 2) + 3 since multiplication has a higher precedence than addition
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  Associativity • When anexpression has two operators with the same precedence, the expression is evaluated according to its associativity. For example: x = y = z = 17 is treated as x = (y = (z = 17)) leaving all three variables with the value 17, since the = operator has right-to-left associativity. On the other hand, 72 / 2 / 3 is treated as (72 / 2) / 3 since the / operator has left-to-right associativity.
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  Precedence and Associativity ofJava Operators Operator Description Level Associativity [] Access array element 1 Left to right . Access object member () Invoke a method ++ Post-increment -- Post-decrement ++ Pre-increment 2 Right to left -- Pre-decrement + Unary plus - Unary minus ! Logical NOT ~ Bitwise NOT
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  Operator Description LevelAssociativity () Cast 3 Right to left new Object creation * Multiplicative 4 Left to right / % + - Additive 5 Left to right + String concatenation << >> Shift 6 Left to right >>> < <= Relational type comparison 7 Left to right > >= == Equality 8 Left to right != & Bitwise AND 9 Left to right ^ Bitwise XOR 10 Left to right
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  Operator Description LevelAssociativity | Bitwise OR 11 Left to right && Conditional AND 12 Left to right || Conditional OR 13 Left to right ?: Conditional 14 Right to left = += -= Assignment 15 Right to left *= /= %= &= ^= |= <<= >>= >>>=
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