004 - Operators

Question 1

Which operator is evaluated from right to left?

Answer 1

The assignment operator

Question 2

Which is the order of precedence for operators?

Answer 2

postfix
unary
multiplicative
additive	
shift 
relational
equality	
bitwise AND	
bitwise exclusive OR	
bitwise inclusive OR
logical AND
logical OR
ternary
assignment

Question 3

Which are the postfix operators?

Answer 3

expr++

expr–

Question 4

Which are the unary operators?

Answer 4

\++expr 
--expr 
\+expr 
-expr 
~ 
!

Question 5

Which are the

multiplicative operators?

Answer 5

*
/
%

Question 6

Which are the additive operators?

Answer 6

+

-

Question 7

Which are the shift operators?

Answer 7

>

|&raquo_space;>

Question 8

Which is the type comparison operators?

Answer 8

instanceof

Question 9

Which are the equality and relational operators?

Answer 9

==
!=
>
>=

Question 10

Which are the bitwise operators?

Answer 10

Bitwise inclusive AND &
bitwise exclusive OR ^
bitwise inclusive OR |

Question 11

Which are the logical operators?

Answer 11

logical AND &&

logical OR ||

Question 12

Which are the ternary operators?

Answer 12

?

:

Question 13

Which are the assignment operators?

Answer 13

= 
\+= 
-= 
*=
 /= 
%= 
&= 
^= 
|= 
>= 
>>>=

Question 14

What is concatenation and how is it used?

Answer 14

Joining two strings together

By using the operator +

Question 15

What can a unary operator do?

Answer 15

operations such as
incrementing/decrementing a value by one,
negating an expression,
or inverting the value of a boolean.

Question 16

Where can the increment and decrement operators be used?

Answer 16

As prefix or postfix

Question 17

What is the difference between a prefix and a postfix increment/decrement operator?

Answer 17

the prefix version (++result) evaluates to the incremented value,

the postfix version (result++) evaluates to the original value.

Question 18

What is the difference between = and ==?

Answer 18

= assignment operator

== equality operator

Question 19

What is short-circuiting behavior?

Answer 19

the second operand is evaluated only if needed.

It is used with conditional-AND and conditional-OR operators (&& and ||)

Question 20

What is ?: and how is it used?

Answer 20

The ternary operator or if-then-else statement

If someCondition is true, assign the value of value1 to result. Otherwise, assign the value of value2 to result.”

Question 21

When is useful to use the ? : operator?

Answer 21

if it makes the code more readable;

E.g., when the expressions are compact and without side-effects (such as assignments).

Question 22

In which direction are operators evaluated?

Answer 22

From left to right, except for the assignment operator

Question 23

Which operator can be used to test if an object is an instance of a class, of a subclass, or of a class that implements a particular interface.

Answer 23

instanceof

Question 24

What is null an instance of?

Answer 24

Nothing

Question 25

Which operator inverts a bit pattern. When applied to any of the integral types, makes every “0” a “1” and every “1” a “0”.?

Answer 25

The unary bitwise complement operator “~”.

Question 26

Which operator shifts a bit pattern to the left?

Answer 26

The signed left shift operator “

Question 27

Which operator shifts a bit pattern to the right?

Answer 27

The signed right shift operator “»” shifts a bit pattern to the right,

Question 28

Which operator shifts a zero into the leftmost position?

Answer 28

The unsigned right shift operator “»>” shifts a zero into the leftmost position.

Question 29

Which operator performs a bitwise AND operation?

Answer 29

The bitwise & operator

Question 30

Which operator performs a bitwise inclusive OR operation?

Answer 30

The bitwise ^ operator

Question 31

Which operator performs a bitwise exclusive OR operation?

Answer 31

The bitwise | operator

Question 32

Consider the following code snippet.
arrayOfInts[j] > arrayOfInts[j+1]
Which operators does the code contain?

Answer 32

Relational > (greater than)

Arithmetical additional + (addition)

Question 33

Consider the following code snippet.
int i = 10;
int n = i++%5;
a. What are the values of i and n after the code is executed?

b.What are the final values of i and n if instead of using the postfix increment operator (i++), you use the prefix version (++i))?

Answer 33

a.
i = 11
n = 0

b.
i = 11
n = 1

Question 34

To invert the value of a boolean, which operator would you use?

Answer 34

! (Logical complement)

Question 35

Which operator is used to compare two values, = or == ?

Answer 35

== comparison

= assignment

Question 36

Explain the following code sample: result = someCondition ? value1 : value2;

Answer 36

If someCondition is true, the result will be assigned the value of value1. If it is false, the result will be assigned the value value2

Question 37

Change the following program to use compound assignments:
class ArithmeticDemo {

 public static void main (String[] args){

      int result = 1 + 2; // result is now 3
      System.out.println(result);

      result = result - 1; // result is now 2
      System.out.println(result);

      result = result * 2; // result is now 4
      System.out.println(result);

      result = result / 2; // result is now 2
      System.out.println(result);

      result = result + 8; // result is now 10
      result = result % 7; // result is now 3
      System.out.println(result);
 } }

Answer 37

class ArithmeticDemo {

public static void main (String[] args){
    int result = 3;
    System.out.println(result);

    result -= 1; // result is now 2
    System.out.println(result);

    result *= 2; // result is now 4
    System.out.println(result);

    result /= 2; // result is now 2
    System.out.println(result);

    result += 8; // result is now 10
    result %= 7; // result is now 3
    System.out.println(result);

} }

Question 38

In the following program, explain why the value "6" is printed twice in a row:
class PrePostDemo {
    public static void main(String[] args){
        int i = 3;
        i++;
        System.out.println(i);    // "4"
        \++i;                     
        System.out.println(i);    // "5"
        System.out.println(++i);  // "6"
        System.out.println(i++);  // "6"
        System.out.println(i);    // "7"
    }
}

Answer 38

The code System.out.println(++i); evaluates to 6, because the prefix version of ++ evaluates to the incremented value. The next line, System.out.println(i++); evaluates to the current value (6), then increments by one. So “7” doesn’t get printed until the next line.

Question 39

pensar

Answer 39

think
thought
thought