Which of the following is the correct precedence of logical operators?

1. !, &&, ||
2. &&, !, ||
3. ||, !, &&
4. &&, ||, !

Answer

!, &&, ||

Reason — The correct precedence of logical operators is !, &&, ||.

Choose the odd one out from the following:

1. >
2. ==
3. &&
4. <

Answer

&&

Reason — && is the logical AND whereas the other operators are relational.

Given: String st = (a>= 90)? "Excellent": "Best";
Predict the output, when a = 90.

1. Best
2. Excellent: Best
3. Best: Excellent
4. Excellent

Answer

Excellent

Reason — Since condition (a>= 90) of ternary operator is true, st is assigned the value of expression 1 i.e., excellent.

Choose the odd one out from the following:

1. Unary operator
2. Binary operator
3. Ternary operator
4. Bitwise operator

Answer

Bitwise operator

Reason — Unary operator, Binary operator and ternary operator are arithmetic operators.

Given: x += x++ + ++x + --x
Find the value, when x=5.

1. 23
2. 21
3. 22
4. 24

Answer

23

Reason — The expression is calculated as follows:

x = x + (x++ + ++x + --x)       (x = 5)
x = 5 + (5 + ++x + --x)         (x = 6)  
x = 5 + (5 + 7 + --x)           (x = 7)  
x = 5 + (5 + 7 + 6)             (x = 6)  
x = 5 + 18
x = 23

The precedence of operators in Java follows BODMAS.
False

The output of a++ will be 1, if int a = -1.
False

The relational operators always result in terms of 'True' or 'False'.
True

Given: int m=5; m*=5 then the value stored in m results in 55.
False

The statement (a>b)&&(a>c) uses a logical operator.
True

If int a=27,b=4,c=0; then c = a % b; results in 3.
True

The statement p += 5 means p = p*5.
False

In the precedence of logical operators; NOT is followed by AND.
True

$\sqrt[3]{\text{ab} + \text{cd}}$

Answer

Math.cbrt(a * b + c * d)

$\text{p}^3 + \text{q}^4 - \dfrac{1}{2}\text{r}$

Answer

Math.pow(p, 3) + Math.pow(q, 4) - (1.0 / 2.0 * r)

$\dfrac{-\text{b} + \sqrt{\text{b}^2 - 4\text{ac}}}{2\text{a}}$

Answer

(-b + Math.sqrt((b * b) - (4 * a * c))) / (2.0 * a)

$\dfrac{0.05 -2\text{y}^3}{(\text{x} - \text{y})}$

Answer

(0.05 - (2 * Math.pow(y,3))) / (x - y)

$\sqrt{\text{mn}} + \sqrt[3]{(\text{m} + \text{n})}$

Answer

Math.sqrt(m * n) + Math.cbrt(m + n)

$\dfrac{3}{4}(\text{a} + \text{b}) - \dfrac{2}{5}\text{ab}$

Answer

(3.0 / 4.0 * (a + b)) - (2.0 / 5.0 * a * b)

$\dfrac{3}{8}\sqrt{(\text{b}^2 + \text{c}^3)}$

Answer

3.0 / 8.0 * Math.sqrt((Math.pow(b,2) + Math.pow(c,3)))

$\sqrt[3]{\text{a}} + \text{b}^2 - \sqrt[3]{\text{c}}$

Answer

Math.cbrt(a) + Math.pow(b,2) - Math.cbrt(c)

$\dfrac{\sqrt{\text{a} + \text{b}^2 + \text{c}^3}}{3}$

Answer

Math.sqrt(a + Math.pow(b,2) + Math.pow(c,3)) / 3

$\dfrac{\sqrt{3\text{x} + \text{x}^2}}{(\text{a} + \text{b})}$

Answer

Math.sqrt(3 * x + Math.pow(x,2)) / (a + b)

$\text{z} = \text{x}^3 + \text{y}^3 - \dfrac{\text{y}}{\text{z}^3}$

Answer

z = Math.pow(x,3) + Math.pow(y,3) - y / Math.pow(z,3)

$\text{q} = \dfrac{1}{\sqrt{\text{a} + \text{b}}} + \dfrac{3}{\text{c}^2}$

Answer

q = 1 / Math.sqrt(a + b) + 3 / Math.pow(c,2)

int c = (3<4)? 3*4 : 3+4;

12

As 3 is less than 4 so condition of ternary operator is true. Variable c is assigned the value of expression 1 which is 3 * 4 = 12.

int a = 14, b = 4; boolean x = (a > b) ? true : false;

true

As 14 is greater than 4 so condition of ternary operator is true. Variable x is assigned the value of expression 1 which is true.

int x = 90;
char c = (x<=90)? 'Z' : 'I';

Z

As value of x is 90 so condition of ternary operator is true. Variable c is assigned the value of expression 1 which is Z.

int a = 18; int b = 12;
boolean t = (a > 20 && b < 15)? true : false;

false

The condition a > 20 is false as value of a is 18. So the logical AND operator — && returns false. Variable t is assigned the value of expression 2 which is false.

c = (val + 550 < 1700)? 200: 400;
if: (a) val = 1000         (b) val = 1500

(a) 200
(b) 400

When val = 1000, val + 550 = 1550. As 1550 is less than 1700 so condition of ternary operator is true. Variable c is assigned the value of expression 1 which is 200.
When val = 1500, val + 550 = 2050. As 2050 is greater than 1700 so condition of ternary operator is false. Variable c is assigned the value of expression 2 which is 400.

What is an operator? What are the three main types of operators? Name them.

Answer

An operator is a symbol or sign used to specify an operation to be performed in Java programming.

The three main types of operators are Arithmetical, Logical and Relational.

How is Java expression different from statement?

Answer

An expression is a set of variables, constants and operators i.e. an expression is a combination of operators and operands. When an expression is assigned to a variable, the complete set is referred to as a statement.

Explain the following with one example each.

(a) Arithmetic operator

Answer

Arithmetic operators are used to perform mathematical operations on its operands. Operands of arithmetic operators must be of numeric type. A few arithmetic operators operate upon one operand. They are called Unary Arithmetic operators. Other arithmetic operators operate upon two operands. They are called Binary Arithmetic operators.
As an example consider the below statement:
int a = 10 + 20;
Here, the addition arithmetic operator, represented by the symbol + will add 10 and 20. So variable a will be 30.

(b) Relational operator

Answer

Relational operators are used to determine the relationship between the operands. Relational operators compare their operands to check if the operands are equal to ( == ), not equal to ( != ), less than ( < ), less than equal to ( <= ), greater than ( > ), greater than equal to ( >= ) each other. The result of an operation involving relation operators is a boolean value — true or false.
Example:
int a = 8;
int b = 10;
boolean c = a < b;
Here, as a is less than b so the result of a < b is true. Hence, boolean variable c becomes true.

(c) Logical operator

Answer

Logical operators operate on boolean expressions to combine the results of these boolean expression into a single boolean value.
Example:
int a = 7;
int b = 10;
boolean c = a < b && a % 2 == 0;
Here, the result of first boolean expression a < b is true and the result of second boolean expression a % 2 is false. The logical AND operator ( && ) combines these true and false boolean values and gives a resultant boolean value as false. So, boolean variable c becomes false.

(d) Ternary operator

Answer

Ternary operator operates on three operands. Its syntax is:

condition ? expression 1 : expression 2

Ternary operator evaluates the condition. If the condition is true then result of ternary operator is the value of expression 1. Otherwise the result is the value of expression 2.
Example:
boolean isLeapYear = true;
int febDays = isLeapYear ? 29 : 28;
Here, the ternary operator checks if the value of boolean variable isLeapYear is true or false. As it is true, expression 1, which in this example is the value 29, is the result of the ternary operator. So, int variable febDays becomes 29.

Distinguish between:

(a) Unary & Binary arithmetic operator

Answer

(b) Postfix increment and Prefix increment

Answer

(c) Postfix decrement and Prefix decrement

Answer

(d) (p != q) and !(p == q)

Answer

What is the difference between

(a) / and % operator?

Answer

(b) = and == ?

Answer

What will be the output of the following code?

int k=5,j=9;
k += k++ - ++j + k;
System.out.println("k="+k);
System.out.println("j="+j);

k=6
j=10

    k+= k++ - ++j + k
⇒ k = k + (k++ - ++j + k)
⇒ k = 5 + (5 - 10 + 6)
⇒ k = 5 + 1
⇒ k = 6

If int y =10 then find int z = (++y*(y++ + 5));

z = 176

    z = (++y * (y++ + 5))
⇒ z = (11 * (11 + 5))
⇒ z = (11 * 16)
⇒ z = 176

Give the output of the following expression:
a += a++ + ++a + --a + a--; when a = 7;

a = 39

    a+= a++ + ++a + --a + a--
⇒ a = a + (a++ + ++a + --a + a--)
⇒ a = 7 + (7 + 9 + 8 + 8)
⇒ a = 7 + 32
⇒ a = 39

What is the value of y after the execution?
y += ++y + y-- + --y; when int y=8

y = 33

    y+= ++y + y-- + --y
⇒ y = y + (++y + y-- + --y)
⇒ y = 8 + (9 + 9 + 7)
⇒ y = 8 + 25
⇒ y = 33

Rewrite the following program segment using if-else statements instead of the ternary operator.

(a) String grade = (marks>=90)?"A": (marks>=80)? "B": "C";

Answer

String grade;
if (marks >= 90)
    grade = "A";
else if (marks >= 80)
    grade = "B";
else
    grade = "C";

(b) commission = (sale > 5000) ? sale*10/100 : 0;

Answer

if (sale > 5000)
    commission = sale * 10 / 100;
else
    commission = 0;

(c) net = (salary > 10000) ? salary - (8.33/100)*salary : salary - (5/100)*salary

Answer

if (salary > 10000)
    net = salary - (8.33/100) * salary;
else
    net = salary - (5/100) * salary;

(d) s = (a + b < c || a + c <= b || b + c <= a) ? "Triangle is not possible": "Triangle is possible";

Answer

if (a + b < c || a + c <= b || b + c <= a)
    s = "Triangle is not possible";
else
    s = "Triangle is possible";

(e) c = (x >= 'A' && x <= 'Z') ? "Upper Case Letter" : "Lower Case Letter";

Answer

if (x >= 'A' && x <= 'Z')
    c = "Upper Case Letter";
else
    c = "Lower Case Letter";

Rewrite the following using ternary operator.

(a)

if (x % 2 == 0)
    System.out.println("Even");
else
    System.out.println("Odd");

Answer

System.out.println(x % 2 == 0 ? "Even" : "Odd");

(b)

if (bill > 10000)
    discount=bill*10.0/100;
else
    discount=bill*5.0/100;

Answer

discount = bill > 10000 ? bill*10.0/100 : bill*5.0/100;

(c)

if(income < 10000)
    tax = 0;
else
    tax = 12;

Answer

tax = income < 10000 ? 0 : 12;

(d)

if(a > b)
{
    if (a > c)
        g = a;
    else
        g = c;
}
else if (b > c)
    g = b;
else
    g = c;

Answer

g = a > b ? a > c ? a : c : b > c ? b : c;

(e)

if (p >= 4750)
    k = p * 5 / 100;
else
    k = p * 10 / 100;

Answer

k = (p >= 4750) ? p * 5 / 100 : p * 10 / 100;