**Relational Operators**

* Relational operators always result in a boolean value (true or false).

* There are six relational operators: >, >=, <, <=, ==, and !=. The last two (== and !=) are sometimes referred to as equality operators. * When comparing characters, Java uses the Unicode value of the character as the numerical value. * Equality operators - There are two equality operators: == and !=. - Four types of things can be tested: numbers, characters, booleans, and

**reference variables.**

* When comparing reference variables, == returns true only if both references refer to the same object.

**instanceof Operator**

* instanceof is for reference variables only, and checks for whether the object is of a particular type.

* The instanceof operator can be used only to test objects (or null) against class types that are in the same class hierarchy.

* For interfaces, an object passes the instanceof test if any of its superclasses implement the interface on the right side of the instanceof operator.

**Arithmetic Operators**

* There are four primary math operators: add, subtract, multiply, and divide.

* The remainder operator (%), returns the remainder of a division.

* Expressions are evaluated from left to right, unless you add parentheses, or unless some operators in the expression have higher precedence than others.

* The *, /, and % operators have higher precedence than + and -.

**String Concatenation Operator**

* If either operand is a String, the + operator concatenates the operands.

* If both operands are numeric, the + operator adds the operands.

**Increment/Decrement Operators**

* Prefix operators (++ and --) run before the value is used in the expression.

* Postfix operators (++ and --) run after the value is used in the expression.

* In any expression, both operands are fully evaluated before the operator is applied.

* Variables marked final cannot be incremented or decremented.

**Ternary (Conditional Operator)**

* Returns one of two values based on whether a boolean expression is true or false.

- Returns the value after the ? if the expression is true.

- Returns the value after the : if the expression is false.

**Logical Operators**

* The exam covers six “logical” operators: &, |, ^, !, &&, and ||.

* Logical operators work with two expressions (except for !) that must resolve to boolean values.

* The && and & operators return true only if both operands are true.

* The || and | operators return true if either or both operands are true.

* The && and || operators are known as short-circuit operators.

* The && operator does not evaluate the right operand if the left operand is false.

* The || does not evaluate the right operand if the left operand is true.

* The & and | operators always evaluate both operands.

* The ^ operator (called the “logical XOR”), returns true if exactly one operand is true.

* The ! operator (called the “inversion” operator), returns the opposite value of the boolean operand it precedes.

Previous Chapter: Chapter 26 - Logical Operators

Next Chapter: Self Test - Chapters 22 to 26

## No comments:

## Post a Comment