Question 1

Question 1What is meant by token? Name the tokens available in Java.

Accepted Answer

The smallest individual unit in a program is called a token.Keywords, identifiers, literals, operators and punctuators are tokens available in Java.

Question 2

Question 2What are keywords ? Can keywords be used as identifiers ?

Accepted Answer

Keywords are the words with special meaning associated with them. These are reserved for special purpose and must not be used as normal identifier names. Some keywords of Java are default, return, if, private etc.No, keywords cannot be used as identifiers.

Question 3

Question 3What is an identifier ? What is the identifier forming rule(s) of Java?

Accepted Answer

Identifiers are the names given by the programmer to various program units of Java. Identifiers are the names of variables, methods, classes, packages and interfaces etc.Identifier forming rules of Java state the following:Identifiers can have alphabets, digits, _ (underscore) and $	ext{	extdollar}$ characters and can be of any length.They must not be a keyword or Boolean literal or null literal.They must not begin with a digit.Java is case sensitive i.e., upper-case letters and lower-case letters are treated differently.

Question 4

Question 4What kind of program elements are the following ?13, 'a', 4.38925, "a", main( )

Accepted Answer

13Integer Literal'a'Character Literal4.38925Floating point Literal"a"String Literalmain( )Method

Question 5

Question 5What kind of constants are the following ?14, 011, 0X2A, 17, 014, 0XBC1

Accepted Answer

14Decimal Integer Literal011Octal Integer Literal0X2AHexadecimal Integer Literal17Decimal Integer Literal014Octal Integer Literal0XBC1Hexadecimal Integer Literal

Question 6

Question 6What is a character constant in Java ? How are non graphic characters represented in Java ?

Accepted Answer

Single character enclosed in single quotation marks (' ') makes a character literal. For example, 'a', '5', $	ext{	extdollar}$, '1' are character literals.Non-graphic characters are represented in Java using escape sequence. An escape sequence is represented by a backslash (\) followed by one or more characters. For example, '
', '	' are escape sequences for new line and tab respectively.

Question 7

Question 8What is meant by implicit and explicit type conversion ?

Accepted Answer

In an implicit conversion, the result of a mixed mode expression is obtained in the higher most data type of the variables without any intervention by the user. For example:int a = 10;
float b = 25.5f, c;
c = a + b;
In case of explicit type conversion, the data gets converted to a type as specified by the programmer. For example:int a = 10;
double b = 25.5;
float c = (float)(a + b);

Question 8

Question 9What do you mean by type casting? What is type cast operator in Java?

Accepted Answer

The explicit conversion of an operand to a specific type is called Type Casting.Type Casting in Java is done using the type cast operator. It is a unary operator. It's syntax is:() For example :int a = 10; double b = 25.5; float c = (float)(a + b);

Question 9

Question 10What will be the resultant type of the following expression if bh represents a byte variable, i is an int variable, fl is a float variable and db is a double variable ?bh - i + db / fl - i * fl + db / i

Accepted Answer

The resultant data type will be double.Explanation    bh - i + db / fl - i * fl + db / i⇒ byte - int + double / float - int * float + double / int⇒ byte - int + double - float + double⇒ int + double - float + double⇒ double - float + double⇒ double + double⇒ double

Question 10

Question 11What will be the resultant type of the following expression if fl is a float variable and db is a double variable?(int) (fl + db)

Accepted Answer

The resultant data type will be int.ExplanationHere, the programmer is performing an explicit type conversion to int using the type cast operator. Hence, the resultant data type will be int.

Question 11

Question 12Determine the data type of the expression(100(1−pq)(q+r))−((p+r)/s(long)(s+p))\Big(\dfrac{100(1 - pq)}{(q + r)}\Big) - \Big(\dfrac{(p + r) / s}{(	ext{long})(s + p)}\Big)((q+r)100(1−pq)​)−((long)(s+p)(p+r)/s​)If p is an int, r is a float, q is a long and s is double.

Accepted Answer

The result of the given expression will be double type.Explanation(int∗(int−int∗long)(long + float))−((int+float)/double(long)(double+int))⇒(int∗(int−long)float)−(float/doublelong)⇒(int∗intfloat)−(doublelong)⇒float−double⇒double\Big(\dfrac{\text{int} * (\text{int} - \text{int} * \text{long})}{\text{(\text{long} + \text{float})}}\Big) - \Big(\dfrac{(\text{int} + \text{float}) / \text{double}}{(\text{long})(\text{double} + \text{int})}\Big) \[1em] \Rightarrow \Big(\dfrac{\text{int} * (\text{int} - \text{long})}{\text{float}}\Big) - \Big(\dfrac{\text{float} / \text{double}}{\text{long}}\Big) \[1em] \Rightarrow \Big(\dfrac{\text{int} * \text{int}}{\text{float}}\Big) - \Big(\dfrac{\text{double}}{\text{long}}\Big) \[1em] \Rightarrow \text{float} - \text{double} \[1em] \Rightarrow \text{double}((long + float)int∗(int−int∗long)​)−((long)(double+int)(int+float)/double​)⇒(floatint∗(int−long)​)−(longfloat/double​)⇒(floatint∗int​)−(longdouble​)⇒float−double⇒double

Question 12

Question 13Determine the data type of the expression(2x+3y5w+6z+8p5q)4\Big(\dfrac{2x + 3y}{5w + 6z} + \dfrac{8p}{5q}\Big)^4(5w+6z2x+3y​+5q8p​)4if x is int, y is long, w is float, z is double, p is short and q is long double.

Accepted Answer

The result will be of long double data type.Explanation(int+longfloat+double+shortlong double)4⇒(longdouble+shortlong double)4⇒(double+long double)4⇒long double\Big(\dfrac{\text{int} + \text{long}}{\text{float} + \text{double}} + \dfrac{\text{short}}{\text{long double}}\Big)^4 \[1em] \Rightarrow \Big(\dfrac{\text{long}}{\text{double}} + \dfrac{\text{short}}{\text{long double}}\Big)^4 \[1em] \Rightarrow \Big(\text{double} + \text{long double}\Big)^4 \[1em] \Rightarrow \text{long double}(float+doubleint+long​+long doubleshort​)4⇒(doublelong​+long doubleshort​)4⇒(double+long double)4⇒long double

Question 13

Question 14(a)State the value and type of each expression.Math.abs(-5) - Math.abs(-7)

Accepted Answer

The output value is -2. The type of expression is int.Explanation    Math.abs(-5) - Math.abs(-7)⇒ 5 - 7⇒ -2

Question 14

Question 14(b)State the value and type of each expression.Math.abs(-1e-1) +  Math.abs(-2e-2)

Accepted Answer

The output value is 0.12. The type of expression is double.Explanation    Math.abs(-1e-1) + Math.abs(-2e-2)⇒ 0.1 + 0.02⇒ 0.12

Question 15

Question 14(c)State the value and type of each expression.Math.sqrt(0.0064)

Accepted Answer

The output value is 0.08. The type of expression is double.ExplanationMath.sqrt() method returns the square root of its argument. As square root of 0.0064 is 0.08 hence that is the output. The return type of Math.sqrt() is double so the type of expression is double.

Question 16

Question 14(d)State the value and type of each expression.Math.sqrt(Math.pow(2.7, 2))

Accepted Answer

The output value is 2.7. The type of expression is double.ExplanationMath.pow(2.7, 2) will calculate square of 2.7 as we are raising it to the power 2. After this, calculating square root with Math.sqrt() will return the same number 2.7. The return type of Math.sqrt() is double so the type of expression is double.

Question 17

Question 14(e)State the value and type of each expression.Math.round(3.499)

Accepted Answer

The output value is 3. The type of expression is long.ExplanationMath.round() rounds off its argument to the nearest mathematical integer. If argument is float, return type is int, if argument is double, return type is long. In this case, 3.499 will be treated as double because suffix 'f' is not there. Hence, it will return a value of long data type.

Question 18

Question 14(f)State the value and type of each expression.Math.max(1.5e-2, 0.095)

Accepted Answer

The output value is 0.095. The type of expression is double.ExplanationMath.max(a, b) returns the maximum of a and b. As 0.095 is greater than 1.5e-2, hence, 0.095 is the output. Since the argument is double so the data type of return value is also double.

Question 19

Question 14(g)State the value and type of each expression.Math.ceil(4.002)

Accepted Answer

The output value is 5.0. The type of expression is double.ExplanationMath.ceil(x) returns the smallest double value that is greater than or equal to the argument and is equal to a mathematical integer. Hence, output is 5.0 and data type of result is double.

Question 20

Question 14(h)State the value and type of each expression.Math.min(-5, 1.0)

Accepted Answer

The output value is -5.0. The type of expression is double.ExplanationMath.min(a, b) returns the minimum of a and b. As one of the arguments is of double type hence, data type of return value is also double.

Revising Basic Java Concepts

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