Java Questions & Answers – Integer and Floating Data Types
1. What is the range of short data type in Java? a) -128 to 127 b) -32768 to 32767 c) -2147483648 to 2147483647 d) None of the mentioned Answer: b 2. What is the range of byte data type in Java? a) -128 to 127 b) -32768 to 32767 c) -2147483648 to 2147483647 d) None of the mentioned Answer: a 3. Which of the following are legal lines of Java code?
a. int w = (int)888.8;
b. byte x = (byte)100L;
c. long y = (byte)100;
d. byte z = (byte)100L;
a) 1 and 2 b) 2 and 3 c) 3 and 4 d) All statements are correct Answer: d 4. An expression involving byte, int, and literal numbers is promoted to which of these? a) int b) long c) byte d) float Answer: a 5. Which of these literals can be contained in float data type variable? a) -1.7e+308 b) -3.4e+038 c) +1.7e+308 d) -3.4e+050 Answer: b 6. Which data type value is returned by all transcendental math functions? a) int b) float c) double d) long Answer: c 7. What will be the output of the following Java code?
class average {
public static void main(String args[])
{
double num[] = {5.5, 10.1, 11, 12.8, 56.9, 2.5};
double result;
result = 0;
for (int i = 0; i < 6; ++i)
result = result + num[i];
System.out.print(result/6);
}
}
a) 16.34 b) 16.566666644 c) 16.46666666666667 d) 16.46666666666666 Answer: c 8. What will be the output of the following Java statement?
class output {
public static void main(String args[])
{
double a, b,c;
a = 3.0/0;
b = 0/4.0;
c=0/0.0;
System.out.println(a);
System.out.println(b);
System.out.println(c);
}
}
a) Infinity b) 0.0 c) NaN d) all of the mentioned Answer: d 9. What will be the output of the following Java code?
class increment {
public static void main(String args[])
{
int g = 3;
System.out.print(++g * 8);
}
}
a) 25 b) 24 c) 32 d) 33 Answer: c 10. What will be the output of the following Java code?
class area {
public static void main(String args[])
{
double r, pi, a;
r = 9.8;
pi = 3.14;
a = pi * r * r;
System.out.println(a);
}
}
a) 301.5656 b) 301 c) 301.56 d) 301.56560000 Answer: a
Java Questions & Answers – Character and Boolean Data Types
1. What is the numerical range of a char data type in Java? a) -128 to 127 b) 0 to 256 c) 0 to 32767 d) 0 to 65535 Answer: d 2. Which of these coding types is used for data type characters in Java? a) ASCII b) ISO-LATIN-1 c) UNICODE d) None of the mentioned Answer: c 3. Which of these values can a boolean variable contain? a) True & False b) 0 & 1 c) Any integer value d) true Answer: a 4. Which of these occupy first 0 to 127 in Unicode character set used for characters in Java? a) ASCII b) ISO-LATIN-1 c) None of the mentioned d) ASCII and ISO-LATIN1 Answer: d 5. Which one is a valid declaration of a boolean? a) boolean b1 = 1; b) boolean b2 = ‘false’; c) boolean b3 = false; d) boolean b4 = ‘true’ Answer: c 6. What will be the output of the following Java program?
class array_output {
public static void main(String args[])
{
char array_variable [] = new char[10];
for (int i = 0; i < 10; ++i) {
array_variable[i] = 'i';
System.out.print(array_variable[i] + "" );
i++;
}
}
}
a) i i i i i b) 0 1 2 3 4 c) i j k l m d) None of the mentioned Answer: a 7. What will be the output of the following Java program?
class mainclass {
public static void main(String args[])
{
char a = 'A';
a++;
System.out.print((int)a);
}
}
a) 66 b) 67 c) 65 d) 64 Answer: a 8. What will be the output of the following Java program?
class mainclass {
public static void main(String args[])
{
boolean var1 = true;
boolean var2 = false;
if (var1)
System.out.println(var1);
else
System.out.println(var2);
}
}
a) 0 b) 1 c) true d) false Answer: c 9. What will be the output of the following Java code?
1. What is the order of variables in Enum? a) Ascending order b) Descending order c) Random order d) Depends on the order() method Answer: a 2. Can we create an instance of Enum outside of Enum itself? a) True b) False Answer: b 3. What will be the output of the following Java code?
enum Season
{
WINTER, SPRING, SUMMER, FALL
};
System.out.println(Season.WINTER.ordinal());
a) 0 b) 1 c) 2 d) 3 Answer: a 4. If we try to add Enum constants to a TreeSet, what sorting order will it use? a) Sorted in the order of declaration of Enums b) Sorted in alphabetical order of Enums c) Sorted based on order() method d) Sorted in descending order of names of Enums Answer: a 5. What will be the output of the following Java code snippet?
class A
{
}
enum Enums extends A
{
ABC, BCD, CDE, DEF;
}
a) Runtime Error b) Compilation Error c) It runs successfully d) EnumNotDefined Exception Answer: b 6. What will be the output of the following Java code snippet?
enum Levels
{
private TOP,
public MEDIUM,
protected BOTTOM;
}
a) Runtime Error b) EnumNotDefined Exception c) It runs successfully d) Compilation Error Answer: d 7. What will be the output of the following Java code snippet?
enum Enums
{
A, B, C;
private Enums()
{
System.out.println(10);
}
}
public class MainClass
{
public static void main(String[] args)
{
Enum en = Enums.B;
}
}
d) Runtime Exception Answer: a 8. Which method returns the elements of Enum class? a) getEnums() b) getEnumConstants() c) getEnumList() d) getEnum() Answer: b 9. Which class does all the Enums extend? a) Object b) Enums c) Enum d) EnumClass Answer: c 10. Are enums are type-safe? a) True b) False Answer: a
Java Questions & Answers – Data Type-BigDecimal
1. Which of the following is the advantage of BigDecimal over double? a) Syntax b) Memory usage c) Garbage creation d) Precision Answer: d 2. Which of the below data type doesn’t support overloaded methods for +,-,* and /? a) int b) float c) double d) BigDecimal Answer: d 3. What will be the output of the following Java code snippet?
double a = 0.02;
double b = 0.03;
double c = b - a;
System.out.println(c);
BigDecimal _a = new BigDecimal("0.02");
BigDecimal _b = new BigDecimal("0.03");
BigDecimal _c = b.subtract(_a);
System.out.println(_c);
a)
0.009999999999999998
0.01
b)
0.01
0.009999999999999998
c)
0.01
0.01
d)
0.009999999999999998
0.009999999999999998
Answer: a 4. What is the base of BigDecimal data type? a) Base 2 b) Base 8 c) Base 10 d) Base e Answer: c 5. What is the limitation of toString() method of BigDecimal? a) There is no limitation b) toString returns null c) toString returns the number in expanded form d) toString uses scientific notation Answer: d 6. Which of the following is not provided by BigDecimal? a) scale manipulation b) + operator c) rounding d) hashing Answer: b 7. BigDecimal is a part of which package? a) java.lang b) java.math c) java.util d) java.io Answer: b 8. What is BigDecimal.ONE? a) wrong statement b) custom defined statement c) static variable with value 1 on scale 10 d) static variable with value 1 on scale 0 Answer: d 9. Which class is a library of functions to perform arithmetic operations of BigInteger and BigDecimal? a) MathContext b) MathLib c) BigLib d) BigContext Answer: a 10. What will be the output of the following Java code snippet?
public class AddDemo
{
public static void main(String args[])
{
BigDecimal b = new BigDecimal("23.43");
BigDecimal br = new BigDecimal("24");
BigDecimal bres = b.add(new BigDecimal("450.23"));
System.out.println("Add: "+bres);
MathContext mc = new MathContext(2, RoundingMode.DOWN);
BigDecimal bdecMath = b.add(new BigDecimal("450.23"), mc);
System.out.println("Add using MathContext: "+bdecMath);
}
}
a) Compilation failure b)
Add: 473.66
Add using MathContext: 4.7E+2
c)
Add 4.7E+2
Add using MathContext: 473.66
d) Runtime exception Answer: b
Java Questions & Answers – Data Type-Date, TimeZone
1. How to format date from one form to another? a) SimpleDateFormat b) DateFormat c) SimpleFormat d) DateConverter
Answer: a
2. How to convert Date object to String? a)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
sdf.parse(new Date());
b)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
sdf.format(new Date());
c)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
new Date().parse();
d)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
new Date().format();
Answer: b
3. How to convert a String to a Date object? a)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
sdf.parse(new Date());
b)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
sdf.format(new Date());
c)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
new Date().parse();
d)
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd");
new Date().format();
Answer: a 4. Is SimpleDateFormat thread safe? a) True b) False Answer: b 5. How to identify if a timezone is eligible for DayLight Saving? a) useDaylightTime() of Time class b) useDaylightTime() of Date class c) useDaylightTime() of TimeZone class d) useDaylightTime() of DateTime class Answer: c 6. What is the replacement of joda time library in java 8? a) java.time (JSR-310) b) java.date (JSR-310) c) java.joda d) java.jodaTime Answer: a 7. How is Date stored in database? a) java.sql.Date b) java.util.Date c) java.sql.DateTime d) java.util.DateTime Answer: a 8. What does LocalTime represent? a) Date without time b) Time without Date c) Date and Time d) Date and Time with timezone Answer: b 9. How to get difference between two dates? a) long diffInMilli = java.time.Duration.between(dateTime1, dateTime2).toMillis(); b) long diffInMilli = java.time.difference(dateTime1, dateTime2).toMillis(); c) Date diffInMilli = java.time.Duration.between(dateTime1, dateTime2).toMillis(); d) Time diffInMilli = java.time.Duration.between(dateTime1, dateTime2).toMillis(); Answer: a 10. How to get UTC time? a) Time.getUTC(); b) Date.getUTC(); c) Instant.now(); d) TimeZone.getUTC(); Answer: c
1. Which of these is long data type literal? a) 0x99fffL b) ABCDEFG c) 0x99fffa d) 99671246 Answer: a 2. Which of these can be returned by the operator &? a) Integer b) Boolean c) Character d) Integer or Boolean Answer: d 3. Literals in java must be appended by which of these? a) L b) l c) D d) L and I Answer: d 4. Literal can be of which of these data types? a) integer b) float c) boolean d) all of the mentioned Answer: d 5. Which of these can not be used for a variable name in Java? a) identifier b) keyword c) identifier & keyword d) none of the mentioned Answer: b 6. What will be the output of the following Java program?
class evaluate
{
public static void main(String args[])
{
int a[] = {1,2,3,4,5};
int d[] = a;
int sum = 0;
for (int j = 0; j < 3; ++j)
sum += (a[j] * d[j + 1]) + (a[j + 1] * d[j]);
System.out.println(sum);
}
}
a) 38 b) 39 c) 40 d) 41 Answer: c 7. What will be the output of the following Java program?
class array_output
{
public static void main(String args[])
{
int array_variable [] = new int[10];
for (int i = 0; i < 10; ++i) {
array_variable[i] = i/2;
array_variable[i]++;
System.out.print(array_variable[i] + " ");
i++;
}
}
}
a) 0 2 4 6 8 b) 1 2 3 4 5 c) 0 1 2 3 4 5 6 7 8 9 d) 1 2 3 4 5 6 7 8 9 10 Answer: b 8. What will be the output of the following Java program?
class variable_scope
{
public static void main(String args[])
{
int x;
x = 5;
{
int y = 6;
System.out.print(x + " " + y);
}
System.out.println(x + " " + y);
}
}
a) 5 6 5 6 b) 5 6 5 c) Runtime error d) Compilation error Answer: d 9. Which of these is an incorrect string literal? a) “Hello World” b) “Hello\nWorld” c) “\”Hello World\”” d)”Hello
world”
Answer: d 10. What will be the output of the following Java program?
class dynamic_initialization
{
public static void main(String args[])
{
double a, b;
a = 3.0;
b = 4.0;
double c = Math.sqrt(a * a + b * b);
System.out.println(c);
}
}
a) 5.0 b) 25.0 c) 7.0 d) Compilation Error Answer: a
Java Questions & Answers – Type Conversions, Promotions and Castings
1. Which of these is necessary condition for automatic type conversion in Java? a) The destination type is smaller than source type b) The destination type is larger than source type c) The destination type can be larger or smaller than source type d) None of the mentioned Answer: b 2. What is the prototype of the default constructor of this Java class?
public class prototype { }
a) prototype( ) b) prototype(void) c) public prototype(void) d) public prototype( ) Answer: d 3. What will be the error in the following Java code?
byte b = 50;
b = b * 50;
a) b cannot contain value 100, limited by its range b) * operator has converted b * 50 into int, which can not be converted to byte without casting c) b cannot contain value 50 d) No error in this code Answer: b 4. If an expression contains double, int, float, long, then the whole expression will be promoted into which of these data types? a) long b) int c) double d) float Answer: c 5. What is Truncation is Java? a) Floating-point value assigned to an integer type b) Integer value assigned to floating type c) Floating-point value assigned to an Floating type d) Integer value assigned to floating type Answer: a 6. What will be the output of the following Java code?
a) E U b) U E c) V E d) U F Answer: a 7. What will be the output of the following Java code?
class conversion
{
public static void main(String args[])
{
double a = 295.04;
int b = 300;
byte c = (byte) a;
byte d = (byte) b;
System.out.println(c + " " + d);
}
}
a) 38 43 b) 39 44 c) 295 300 d) 295.04 300 Answer: b 8. What will be the output of the following Java code?
class A
{
final public int calculate(int a, int b) { return 1; }
}
class B extends A
{
public int calculate(int a, int b) { return 2; }
}
public class output
{
public static void main(String args[])
{
B object = new B();
System.out.print("b is " + b.calculate(0, 1));
}
}
a) b is : 2 b) b is : 1 c) Compilation Error d) An exception is thrown at runtime Answer: c 9. What will be the output of the following Java program, if we run as “java main_arguments 1 2 3”?
class main_arguments
{
public static void main(String [] args)
{
String [][] argument = new String[2][2];
int x;
argument[0] = args;
x = argument[0].length;
for (int y = 0; y < x; y++)
System.out.print(" " + argument[0][y]);
}
}
a) 1 1 b) 1 0 c) 1 0 3 d) 1 2 3 Answer: d 10. What will be the output of the following Java program?
class c
{
public void main( String[] args )
{
System.out.println( "Hello" + args[0] );
}
}
a) Hello c b) Hello c) Hello world d) Runtime Error Answer: d
1. Which of these operators is used to allocate memory to array variable in Java? a) malloc b) alloc c) new d) new malloc Answer: c 2. Which of these is an incorrect array declaration? a) int arr[] = new int[5] b) int [] arr = new int[5] c) int arr[] = new int[5] d) int arr[] = int [5] new Answer: d 3. What will be the output of the following Java code?
int arr[] = new int [5];
System.out.print(arr);
a) 0 b) value stored in arr[0] c) 00000 d) Class hashcode in hexadecimal form Answer: d 4. Which of these is an incorrect Statement? a) It is necessary to use new operator to initialize an array b) Array can be initialized using comma separated expressions surrounded by curly braces c) Array can be initialized when they are declared d) None of the mentioned Answer: a 5. Which of these is necessary to specify at time of array initialization? a) Row b) Column c) Both Row and Column d) None of the mentioned Answer: a 6. What will be the output of the following Java code?
class array_output
{
public static void main(String args[])
{
int array_variable [] = new int[10];
for (int i = 0; i < 10; ++i)
{
array_variable[i] = i;
System.out.print(array_variable[i] + " ");
i++;
}
}
}
a) 0 2 4 6 8 b) 1 3 5 7 9 c) 0 1 2 3 4 5 6 7 8 9 d) 1 2 3 4 5 6 7 8 9 10 Answer: a 7. What will be the output of the following Java code?
class multidimention_array
{
public static void main(String args[])
{
int arr[][] = new int[3][];
arr[0] = new int[1];
arr[1] = new int[2];
arr[2] = new int[3];
int sum = 0;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < i + 1; ++j)
arr[i][j] = j + 1;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < i + 1; ++j)
sum + = arr[i][j];
System.out.print(sum);
}
}
a) 11 b) 10 c) 13 d) 14 Answer: b 8. What will be the output of the following Java code?
class evaluate
{
public static void main(String args[])
{
int arr[] = new int[] {0 , 1, 2, 3, 4, 5, 6, 7, 8, 9};
int n = 6;
n = arr[arr[n] / 2];
System.out.println(arr[n] / 2);
}
}
a) 3 b) 0 c) 6 d) 1 Answer: d 9. What will be the output of the following Java code?
class array_output
{
public static void main(String args[])
{
char array_variable [] = new char[10];
for (int i = 0; i < 10; ++i)
{
array_variable[i] = 'i';
System.out.print(array_variable[i] + "");
}
}
}
a) 1 2 3 4 5 6 7 8 9 10 b) 0 1 2 3 4 5 6 7 8 9 10 c) i j k l m n o p q r d) i i i i i i i i i i Answer: d 10. What will be the output of the following Java code?
class array_output
{
public static void main(String args[])
{
int array_variable[][] = {{ 1, 2, 3}, { 4 , 5, 6}, { 7, 8, 9}};
int sum = 0;
for (int i = 0; i < 3; ++i)
for (int j = 0; j < 3 ; ++j)
sum = sum + array_variable[i][j];
System.out.print(sum / 5);
}
}
