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:

1. There are two equality operators. == and !=
2. Four types of things can be tested: Numbers, Characters, and Booleans and Reference variables.
3. When comparing reference variables. == Returns true if both references refer to same object.

Instanceof Operator:

• Instanceof is for reference variables only, and checks for weather the object is of particular type.
• The instance of operator can be used only to test objects (or null) against class types that are in the same hierarchy.
• For interfaces, an object passes the Instanceof test if any of its subclasses 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 division.
• Expressions are evaluated from left to right, unless you add parenthesis, or unless same operators in the expression have higher precedence than others.
• The *, /, and % have higher precedence than + and -.

String concatenation Operators:

• 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 expression.
• Postfix operators (++ and –) run after the value is used in the expression.
• If any expression, both operands fully evaluated before the operator is applied.
• Variables marked as final cannot be incremented or decremented.

Ternary (Conditional operator):

• Returns one of the two values based on the Boolean expression is true of 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 operands (except for !) that must resolve Boolean values.
• The && and & operators returns true if both operands are true.
• The || and | operator returns true if either or both operands are true.
• && and || operators are known as short circuit operators.
• The && operator dose not evaluate the right operand if the left operand is false.
• The || operator doesn’t evaluate the right operand if the left operand is true.
• The & and | operators always evaluate both operands.
• The ^ operator (called logical XOR), returns true if exactly one operand is true.
• The ! Operator (called the inversion operator), returns the opposite value of both Boolean operand it precedes.