Operators & Statements

Question 1

Is the following assignment valid? short = short + short;

Answer 1

No. short is always promoted to int before being used in an arithmetic binary operation, which cannot be assigned back to short.

Question 2

Is the following assignment valid? int = byte + short;

Answer 2

Yes. byte and short are automatically promoted to int before added.

Question 3

Is the following assignment valid? short = short++;

Answer 3

Yes. Unary operators don’t promote shorts.

Question 4

Is the following assignment valid? float f = 4.3;

Answer 4

No. floating-point literals are assumed to be doubles unless postfixed with ‘f’, which cannot be assigned to float.

Question 5

Is the following assignment valid? double = short + float;

Answer 5

Yes. short is promoted to int automatically, then to float to be added, then the result is promoted to double to be assigned.

Question 6

Is the following assignment valid? boolean b = !0;

Answer 6

No. The negation operator is not valid on a numeric value.

Question 7

Is the following assignment valid? int i = 5.0;

Answer 7

No. 5.0 is treated as a double, which cannot be assigned to an int unless casted.

Question 8

Is the following assignment valid? short s = 35000;

Answer 8

No. 35000 exceeds the maximum value of short and can’t be assigned unless casted, and then overflowing would apply.

Question 9

Is the following assignment valid? long l = 35000;

Answer 9

Yes.

Question 10

Is the following assignment valid? long l = 2500000000;

Answer 10

No. 2500000000 exceeds the maximum value of an int. An ‘L’ must follow the literal value to be treated as a long literal.

Question 11

Is the following assignment valid? boolean b = int == null;

Answer 11

No. null cannot be compared to primitives

Question 12

Is the following assignment valid? boolean b = Boolean == null;

Answer 12

Yes.

Question 13

Given int x = 2;, What is the value of the following expression?

x++ + (2 + –x) * ++x;

Answer 13

14. The unary operators are evaluated left to right regardless of parentheses, which simplifies to:
    2 + (2 + 2) * 3;

Question 14

Which of the following types is not supported by switch statements? byte/Byte, short/Short, char/Character, int/Integer, long/Long, enum, String.

Answer 14

long/Long (enum support added in Java 5, String in Java 7)

Question 15

What is a Java operator?

Answer 15

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

Question 16

What is an operand in the context of an operator in Java?

Answer 16

An operand is one of set of variables, values, or literals, which can be used to return a result from an operator.

Question 17

What are the 3 flavors of Java operators?

Answer 17

Unary, binary, and ternary.

Question 18

How many operands can a unary operator be applied to?

Answer 18

1

Question 19

How many operands can a binary operator be applied to?

Answer 19

2

Question 20

How many operands can a ternary operator be applied to?

Answer 20

3

Question 21

What is the order of operator precedence in Java?

Answer 21

Post-unary operators
Pre-unary operators
Other unary operators
Multiplication/Division/Modulus
Addition/Subtraction
Shift operators
Relational operators
Equal to/not equal to
Logical operators
Short-circuit logical operators
Ternary operators
Assignment operators

Question 22

When does Java not follow the rules of operator precedence?

Answer 22

When the order of operation is overridden with parentheses.

Question 23

If all operators are equal, how does Java evaluate an expression?

Answer 23

From left to right.

Question 24

What are the arithmetic operator?

Answer 24

+, -, * /, %, ++, –

Question 25

Which primitives are operands for arithmetic operators?

Answer 25

All except boolean.

Note: A String is not a primitive though some texts treat it that way. The arithmetic + and += perform concatenation on strings, not arithmetic.

Question 26

What is one of the rules of numeric promotion in Java?

Answer 26

If two values have different data types, Java will automatically promote one of the values to the larger of the two data types.

Question 27

What is another rules of numeric promotion in Java?

Answer 27

If one of the value is integral and the other is floating-point, Java will automatically promote the integral value to the floating-point value’s data type.

Question 28

What is yet another rule of numeric promotion in Java?

Answer 28

Smaller data types, namely byte, short, and char, are first promoted to int any time they’re used with a Java binary arithmetic operator, even if neither of the operands is int.

Question 29

What is the other rule of numeric promotion in Java?

Answer 29

After all promotion has occurred and the operands have the same data type, the resulting value will have the same data type as its promoted operands.

Question 30

What does the ‘+’ unary operator do?

Answer 30

Indicates that a number is positive (although numbers in Java are assumed to be positive unless accompanied by a negative unary operator.)

Question 31

What does the ‘-‘ unary operator do? What is it called?

Answer 31

It indicates a literal number is negative or negates an expression. It is called the negation operator.

Question 32

What does the ‘++’ operator do?

Answer 32

Increments a value by 1.

Question 33

What does the ‘–’ operator do?

Answer 33

Decrements a value by 1.

Question 34

What does the ‘!’ operator do? What is it called?

Answer 34

It inverts a Boolean’s logical function. It is called the logical complement operator.

Question 35

Can you apply the logical complement operator to an arithmetic expression?

Answer 35

No.

Question 36

Can you apply the negation operator to a boolean expression?

Answer 36

No.

Question 37

What is the ‘++’ operator called?

Answer 37

The increment operator.

Question 38

What is the ‘–’ operator called?

Answer 38

The decrement operator.

Question 39

What is it called if the increment operator or decrement operator is placed before and operand?

Answer 39

The pre-increment or pre-decrement operator.

Question 40

What is it called if the increment operator or decrement operator is placed after an operand?

Answer 40

The post-increment or post-decrement operator.

Question 41

Which operator has higher precedence in the order of operations, the pre-increment/pre-decrement operators or the post-increment/post-decrement operators?

Answer 41

The pre-increment/pre-decrement operators.