chapter 3

Question 1

What is an operator?

Answer 1

A special symbol that can be applied to a set of variables, values, or literals, and that returns a result.

Question 2

What is an operand?

Answer 2

The value of variable the operator is being applied to.

Question 3

In general, what are the three types of operators available in Java?

Answer 3

unary, binary, and ternary.

Question 4

What is the order of operator precedence?

Answer 4

post-unary operators: foo++, foo--;
pre-unary operators: ++foo, --foo;
unary operators: -,!,~+,(type)
mult/div/mod: *,/,%
add/sub: +,-
shift operators: <>,>>>
relational operators: ,<=,>=,instanceof
equal/not equal: ==, !=
logical operators: &amp;,^,|
short-circuit logical ops: &amp;&amp;, ||
ternary operators: boolean exp? exp1: exp2
assignment ops: =, +=,-=,*=,/=,%=,&amp;=,^=,|=,<<=,>>=,>>>=

Question 5

What is a unary operator?

Answer 5

An operator that requires exactly one operand to function.

Question 6

List the unary operators in Java.

Answer 6

! -> Inverts a boolean logical value
\+ -> Indicates a number is positive
- -> Indicates a literal number is negative, or negates an expression
\++ -> increments a value by 1
-- -> decrements a value by 1
(type) casts a value to a specific type

Question 7

What is a binary operator?

Answer 7

An operator that takes two arguments.

Question 8

List the binary operators.

Answer 8

+ -> Adds two numeric values.
- -> Subtracts two numeric values.
* -> Multiplies two numeric values.
/ -> Divides one numeric value by another.
% -> Returns the remainder after division of one numeric value by another.

Question 9

What is the only primitive type arithmetic operators cannot be applied to?

Answer 9

boolean.

Question 10

What are the only arithmetic operators that can be applied to String types?

Answer 10

+, +=

Question 11

When parentheses are used in the exam, what are two things to pay attention to?

Answer 11

Are parentheses balanced?

How do the parentheses affect order of operations?

Question 12

What are the 4 numeric promotion rules for primitives used during arithmetic operations?

Answer 12

1. If two values differ in type, the value with the smaller type will be promoted to the larger.
2. If one value is integral and the other floating-point, the integral will be promoted to the floating-point value’s data type.
3. Any type smaller than an int will first be promoted to int when used with a Java binary arithmetic operator.
4. The resulting value of some operation will have the same data type as its promoted operands.

Question 13

What is an assignment operator?

Answer 13

A binary operator that modifies the variable on the left side of the operator with the result of the value on the right side of the equation.

Question 14

What is casting?

Answer 14

A unary operation where one data type is explicitly interpreted as another data type.

Question 15

When casting is present on the OCM exam, what are some things one pay attention to?

Answer 15

parentheses and return types.

Question 16

What are the compound assignment operators in Java?

Answer 16

*=
/=

Question 17

Provide an example of a compound operator handling required casting.

Answer 17

long goat = 10;
int sheep = 5;
sheep *= goat;

Question 18

Is the result of an assignment an expression itself?

Answer 18

Yes, it is equal to the value of the assignment;

Question 19

Describe the two equality operators

Answer 19

==
primitives: returns true if the two values represent the same value
objects: returns true if the two values reference the same object
!=
primitives: returns true if the two values represent different values
objects: returns true if the two values do not reference the same object

Question 20

What are the three scenarios where equality operators are used?

Answer 20

1. Comparing two numeric of primitive types. If values are different data types, values are promoted.
2. Comparing two boolean values.
3. Comparing two objects, including null and String values.

Question 21

Describe the relational operators.

Answer 21

< Returns true if the value on the left is strictly less than the value on the right.
<= Returns true if the value on the left is less than or equal to the value on the right.
> Returns true if the value on left is strictly greater than the value on the right.
>= Returns true if the value on the left is greater than or equal to the value on the right.
a isinstanceof b Returns true if the reference that a points to is an instance of a class/subclass/class that implements a particular interface , as named in b.

Question 22

What happens when you call instanceof on a null variable?

Answer 22

It always returns false.

Question 23

Describe the three logical operators.

Answer 23

& : Logical AND is true only if both values are true.
| : Inclusive OR is true if at least one of the values is true.
^ : Exclusive XOR is true only if one value is true and the other is false.

Question 24

What types may logical operators be applied to?

Answer 24

numeric and boolean types.

Question 25

When applied to numeric types what are logical operators referred to as?

Answer 25

bitwise operators.

Question 26

What are some tips to remember how logical operators work?

Answer 26

& is only true if both operands are true.
| is only false if both operands are false.
^ is only true if the operands are different.

Question 27

Describe the short-circuit operators.

Answer 27

&& : Short-circuit AND is true only if both values are true. If the left side is false, then the right side will not be evaluated.
|| : Short-circuit OR is true if at least one of the values is true. If the left side is true, then the right side will not be evaluated.

Question 28

What is the form of the ternary operator?

Answer 28

booleanExpression? expression: expression;