Ch2: Operators and Statements

Question 1

What is an operator?

Answer 1

A symbol applied to a set of variables that returns a result

Question 2

What is an operand?

Answer 2

The value(s) that operators operate on

Question 3

What is the name for the values an operator operates on?

Answer 3

Operands

Question 4

What are the three types of operators (based on operand count)?

Answer 4

unary, binary, and ternary

Question 5

What happens if two operators have the same level of precedence?

Answer 5

Java guarantees left-to-right evaluation

Question 6

What is the order of operator precedence?

Answer 6

1. Post-unary de/increment (x++)
2. Pre-unary de/increment (++x)
3. negation (unary)
4. Multiplicative
5. Additive
6. Shift (bitwise)
7. Relational (greater than/less than)
8. Equality Operators
9. Logical/bitwise operators
10. Short-circuit logical
11. Ternary
12. Assignment

Question 7

What is the % operator name and function?

Answer 7

Modulus, returns remainder (from devision)

Question 8

What are the rules of numeric promotion when performing operations on primitive (non-unary) numeric types?

Answer 8

1. A smaller type will be promoted to match the larger type
2. An integral type will be promoted to match the floating-point type
3. For binary arithmetic operators (not unary), byte, short, and char are always promoted to int
4. The resulting value of an operator will be the same type as the promoted operands

Question 9

What are the unary operators?

Answer 9

++ (increment a value by one)
– (decrement a value by one)
+ (makes a literal positive. Opposite of -)
- (makes a literal negative or negates an expression)
! (inverts a boolean, “logical complement operator”)

Question 10

What does the post-increment operator do?

Answer 10

x++

1. Returns original operand value
2. Increments operand by one

Question 11

What does the pre-increment operator do?

Answer 11

++x

1. Increments operand by one
2. Returns the new value

Question 12

How do you cast a larger primitive number type to a smaller primitive data type, and what happens?

Answer 12

use (type) (eg, int i = (int) 1.0). Will cause underflow or overflow, which basically wraps around the value

Question 13

Considering numeric promotion, does this throw an error, and why/not:
long x = 10;
int y = 5;
y *= x;

Answer 13

No; compound assignment operators will automatically re-cast to the target data type.

Question 14

Considering numeric promotion, does this throw an error, and why/not:
long x = 10;
int y = 5;
y = y * x;

Answer 14

Yes; binary operators return the data type of the larger operand type.

Question 15

Do assignment operators have a return value

Answer 15

Yes, it returns the value that was assigned to the left-hand operand and therefore can be used like this:
y = (x = 3); // x and y == 3

Question 16

What are the logical / bitwise operators?

Answer 16

& - AND
| (pipe) - OR
^ - XOR

Question 17

What are the logical short circuit operators?

Answer 17

&& and ||

Question 18

Which scenarios can we use equality operators

Answer 18

1. Comparing numeric primitive types (they will be promoted, as with math operators)
2. Comparing two boolean values
3. Comparing two objects (not object references!), including string and null types
   Note: Cannot mix and match String, numeric, boolean, and reference types.

Question 19

What is the switch statement syntax?

Answer 19

switch(runtimeValue) {
    case compiletimeValue:
        codeToExecute();
        break;
    ...
    default:
        defaultCase();
}

Question 20

Which data types are supported by switch statement evaluations?

Answer 20

Primitive integral classes and their wrappers (NOT boolean or long), String, and emum.
eg:
* int
* byte
* short
* char
* String
* enum

Question 21

In switch statements, what properties much the case values have?

Answer 21

• the case statement value must be a literal, enum constant, or final constant variable
• must be the same type as the switch value (no promotions or casting will happen)

Question 22

In a switch statement, can a case be a final variable that was passed to the function (eg, can a case be lastName from within class getOrder(final String lastName))

Answer 22

No, even though the provided param was final, because it was passed into the method it’s not constant.

Question 23

List all looping control structures

Answer 23

while (bool) {…}
do {…} while (bool);
for (initialize; booleanExpression; updateStatement) {…}
for (type instance : java.lang.Iterable) {…} // for-each loop

Question 24

What is the format for labels and break statements?

Answer 24

OPTIONAL_LABEL: while (boolExp) {
    //stuff
    break OPTIONAL_LABEL;
}

Question 25

What is the format for the continue statement?

Answer 25

OPTIONAL_LABEL: while (boolExp) {
    //stuff
    continue OPTIONAL_LABEL;
}