Library Classes

Multiple Choice Questions

Question 1

A package contains:

tags
classes
data
arrays

Answer

classes

Reason — A package is a collection of Java classes.

Question 2

Each primitive data type belongs to a specific

block
object
wrapper class
none

Answer

wrapper class

Reason — A wrapper class is a class that contains a primitive data type.

Question 3

Automatic conversion of primitive data into an object of wrapper class is called

autoboxing
explicit conversion
shifting
none

Answer

autoboxing

Reason — Automatic conversion of primitive data into an object of its equivalent wrapper class is called autoboxing.

Question 4

The parseInt() function is a member of

integer wrapper class
character wrapper class
boolean wrapper class
none

Answer

integer wrapper class

Reason — The parseInt() function is a member of integer wrapper class.

Question 5

valueOf() function converts

Primitive type to String
String to primitive type
character to String
None

Answer

String to primitive type

Reason — valueOf() function converts String to primitive type.

Question 6

Which of the following functions checks whether a character is a blank or not?

Character.isBlankSpace( )
Character.isWhiteSpace( )
Character.isEmptySpace( )
Character.isNull( )

Answer

Character.isWhiteSpace( )

Reason — Character.isWhiteSpace( ) returns a boolean type value true if the given argument is a white space and otherwise, it returns false.

Question 7

Which of the following statements is true?

Character.isLowerCase( ) and Character.toLowerCase( ) are same.
Character.isLetter( ) and Character.isAlphabet( ) are same.
parse and valueOf functions are same.
Character.isDigit( ) and Character.isNumber( ) are same.

Answer

parse and valueOf functions are same.

Reason — parse and valueOf functions are used to convert a string to a primitive data type.

Question 8

The variable must be declared ........ type, if a character is to be assigned to it.

char
ch
character
alphanumeric

Answer

char

Reason — The variable must be declared 'char' type, if a character is to be assigned to it.

Fill in the blanks

Question 1

Package is a collection of classes.

Question 2

By default, java.lang package is imported in a Java program.

Question 3

The user can create a data type by using a class.

Question 4

The data type int is included in Integer wrapper class.

Question 5

Wrapper class uses first letter in upper case.

Question 6

String data is converted to float type by using Float.parseFloat(String) function.

Question 7

Conversion from primitive type to wrapper object is called as autoboxing.

Question 8

Each character oriented function uses a wrapper tag Character.

State True or False

Question 1

Java class library includes all the packages.
True

Question 2

Wrapper classes belong to java.util package.
False

Question 3

Array is a non-primitive data type.
True

Question 4

Class is a composite data type.
True

Question 5

Integer.toString() converts integer data to String.
True

Find the output of the following program snippets

Question 1

char ch = '*';
boolean b = Character.isLetter(ch);
System.out.println(b);

Answer

Output

false

Explanation

As Asterisk (*) is not a letter so Character.isLetter() method returns false.

Question 2

char c = 'A';
int n = (int) c + 32;
System.out.println((char)n);

Answer

Output

Explanation

int n = (int) c + 32 ⇒ 65 + 32 ⇒ 97
So, variable n get the value of 97. 97 is the ASCII code of small 'a' so casting n to char, prints 'a' to the console.

Question 3

String s= "7";
int t =Integer.parseInt(s);
t = t + 1000;
System.out.println(t);

Answer

Output

Explanation

Integer.parseInt() converts "7" into an int value i.e. the decimal number 7. t + 1000 adds the number 7 to 1000 giving 1007 as the output.

Question 4

char c = 'B';
int i = 4;
System.out.println(c + i);
System.out.println((int)c + i);

Answer

Output

70
70

Explanation

In the expression c + i, c is of type char and i is of type int. As int is the higher type so char gets promoted to int. Thus, ASCII code of 'B' which is 66 is added to 4 giving the output as 70. This is an example of implicit type conversion.
In the next expression (int)c + i, c which is of char type is explicitly casted to int. Again, ASCII code of 'B' which is 66 is added to 4 giving the output as 70. This is an example of explicit type conversion.

Question 5

char ch = 'y';
char chr = Character.toUpperCase(ch); 
int p = (int) chr;
System.out.println(chr + "\t" + p);

Answer

Output

Y       89

Explanation

Character.toUpperCase()method converts small y to capital Y so chr gets the value of 'Y'. Casting chr to int gives the ASCII code of 'Y' which is 89.

Question 6

int n = 97;
char ch = Character.toUpperCase((char)n);
System.out.println(ch + " Great Victory");

Answer

Output

A Great Victory

Explanation

97 is the ASCII code of small a so Character.toUpperCase((char)n) returns capital A which is stored in ch.

Question 7

char ch = 'x'; int n = 5;
n = n + (int)ch;
char c = (char)n;
System.out.println((char)((int)c-26));

Answer

Output

Explanation

As ASCII code of 'x' is 120, so the expession n + (int)ch ⇒ 5 + 120 ⇒ 125. After that, the expression (char)((int)c-26) ⇒ (char)(125 - 26) ⇒ (char)99 ⇒ 'c' as ASCII code of 'c' is 99. So, c is the final output.

Question 8

char ch = 'A';
char chr = Character.toLowerCase(ch); 
int n = (int)chr-32;
System.out.println((char)n + "\t" + chr);

Answer

Output

A       a

Explanation

Character.toLowerCase() converts 'A' to 'a'. ASCII code of 'a' is 97. n becomes 65 — (int)chr-32 ⇒ 97 - 32 ⇒ 65. 65 is the ASCII code of 'A'.

Case-Study based question

Question 1

Java language uses each primitive data type under a specific packet. Other than a data type, the packet also contains the functions to convert the primitive type into string and vice versa. The computer uses 128 ASCII characters. Each character is assigned a specific numeric code called ASCII code. Java language also has the facility to convert the characters into the ASCII code and vice versa.

Based on the above discussion, answer the following questions:

(a) What is the name given to the packet containing a primitive data type?

(b) What is the function used to convert a string data into integer type?

(d) What is the syntax to convert a string "24" into integer data type?

Answer

(a) Wrapper class

(b) parseInt() or valueOf()

(d) int num = Integer.valueOf("24");

Write the purpose of the following functions

Question 1

Float.parseFloat()

Answer

It is used to convert string data into float data.

Question 2

Double.toString()

Answer

It is used to convert double data to a string.

Question 3

Integer.valueOf()

Answer

It is used to convert string data into the Integer wrapper object.

Question 4

Character.isDigit()

Answer

It is used to check if the character given as its argument is a digit.

Question 5

Character.isWhitespace()

Answer

It is used to check if the character given as its argument is a whitespace.

Answer the following questions

Question 1

What is a package?

Answer

In Java, a package is used to group related classes. Packages are of 2 types:

Built-In packages — These are provided by Java API
User-Defined packages — These are created by the programmers to efficiently structure their code.
java.util, java.lang are examples of built-in packages.

Question 2

What is the significance of '*' while importing a package?

Answer

The asterisk(*) sign indicates that all the classes of the imported package can be used in the program.

Question 3

Define a wrapper class.

Answer

The wrapper class is a class that contains a primitive data type. Whenever an object to a wrapper class is created, a field in memory is allocated to contain a primitive data.

Wrapper classes are present in java.lang package. The different wrapper classes provided by Java are Boolean, Byte, Integer, Float, Character, Short, Long and Double.

Question 4(a)

Differentiate between isUpperCase() and toUpperCase()

Answer

isUpperCase()	toUpperCase()
It is used to check if the character given as its argument is in upper case or not.	It is used to convert the character given as its argument to upper case.
Its return type is boolean.	Its return type is char.

Question 4(b)

Differentiate between parseInt() and toString() functions

Answer

parseInt()	toString()
It converts a string to an integer.	It converts an integer to a string.
Its return type is int.	Its return type is String.

Question 4(c)

Differentiate between primitive type and composite type data

Answer

Primitive Data Types	Composite Data Types
Primitive data types are fundamental data types of Java.	Composite data types are created by using primitive data types.
Primitive data types are built-in data types defined by Java language specification.	Composite data types are defined by the programmer.
Examples of primitive data types are byte, short, int, long, float, double, char, boolean.	Examples of composite data types are Class and Array.

Question 5(a)

int res = 'A';
What is the value of res?

Answer

Value of res is 65.

Question 5(b)

Name the package that contains wrapper classes.

Answer

java.lang package contains wrapper classes.

Question 5(c)

Write the prototype of a function check which takes an integer as an argument and returns a character.

Answer

char check(int n) takes an integer as an argument and returns a character.

Solutions to Unsolved Java Programs on Character Manipulations

Question 1

Write a program in Java to input a character. Find and display the next 10^th character in the ASCII table.

import java.util.Scanner;

public class KboatTenthChar
{
    public static void main(String args[]) {
        
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a character: ");
        char ch = in.next().charAt(0);
        char nextCh = (char)(ch + 10);
        System.out.println("Tenth character from " 
            + ch + " is " + nextCh);    
    }
}

Output

Question 2

Write a program in Java to input a character. Display next 5 characters.

import java.util.Scanner;

public class KboatFiveChars
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter a character: ");
        char ch = in.next().charAt(0);
        
        System.out.println("Next 5 characters from " 
            + ch + " are:");
            
        for (int i = 1; i <= 5; i++) {
            System.out.println(++ch);
        }
    }
}

Output

Question 3

Write a program in Java to generate all the alternate letters in the range of letters from A to Z.

public class KboatAlternateLetters
{
    public static void main(String args[]) {
        for (char ch = 'A'; ch <= 'Z'; ch = (char)(ch + 2)) {
            System.out.println(ch);
        }
    }
}

Output

Question 4

Write a program to input a set of 20 letters. Convert each letter into upper case. Find and display the number of vowels and number of consonants present in the set of given letters.

import java.util.Scanner;

public class Kboat20LetterSet
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter any 20 letters");
        int vc = 0, cc = 0;
        for (int i = 0; i < 20; i++) {
            char ch = in.next().charAt(0);
            ch = Character.toUpperCase(ch);
            if (ch == 'A' || 
                ch == 'E' || 
                ch == 'I' || 
                ch == 'O' || 
                ch == 'U')
                    vc++;
            else if (ch >= 'A' && ch <= 'Z')
                cc++;
        }
        System.out.println("Number of Vowels = " + vc);
        System.out.println("Number of Consonants = " + cc);
    }
}

Output

Question 5

Write a program in Java to accept an integer number N such that 0<N<27. Display the corresponding letter of the alphabet (i.e. the letter at position N).
[Hint: If N =1 then display A]

import java.util.Scanner;

public class KboatInteger2Letter
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter integer: ");
        int n = in.nextInt();
        
        if (n > 0 && n < 27) {
            char ch = (char)(n + 64);
            System.out.println("Corresponding letter = " + ch);
        }
        else {
            System.out.println("Please enter a number in 1 to 26 range");
        }
    }
}

Output

Question 6

Write a program to input two characters from the keyboard. Find the difference (d) between their ASCII codes. Display the following messages:
If d=0 : both the characters are same.
If d<0 : first character is smaller.
If d>0 : second character is smaller.
Sample Input :
D
P
Sample Output :
d= (68-80) = -12
First character is smaller

import java.util.Scanner;

public class KboatASCIIDiff
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.print("Enter first character: ");
        char ch1 = in.next().charAt(0);
        System.out.print("Enter second character: ");
        char ch2 = in.next().charAt(0);
        
        int d = (int)ch1 - (int)ch2;
        if (d > 0)
            System.out.println("Second character is smaller");
        else if (d < 0)
            System.out.println("First character is smaller");
        else
            System.out.println("Both the characters are same");
    }
}

Output

Question 7

Write a program to input a set of any 10 integer numbers. Find the sum and product of the numbers. Join the sum and product to form a single number. Display the concatenated number.
[Hint: let sum=245 and product = 1346 then the number after joining sum and product will be 2451346]

import java.util.Scanner;

public class KboatSumProdConcat
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter 10 integers");
        long sum = 0, prod = 1;
        for (int i = 0; i < 10; i++) {
            int n = in.nextInt();
            sum += n;
            prod *= n;
        }
        
        String s = Long.toString(sum) + Long.toString(prod);
        long r = Long.parseLong(s);
        
        System.out.println("Concatenated Number = " + r);
    }
}

Output

Question 8

Write a menu driven program to generate the upper case letters from Z to A and lower case letters from 'a' to 'z' as per the user's choice.
Enter '1' to display upper case letters from Z to A and Enter '2' to display lower case letters from a to z.

import java.util.Scanner;

public class KboatLetters
{
    public static void main(String args[]) {
        
        Scanner in = new Scanner(System.in);
        System.out.println("Enter '1' to display upper case letters from Z to A");
        System.out.println("Enter '2' to display lower case letters from a to z");
        
        System.out.print("Enter your choice: ");
        int ch = in.nextInt();
        int count = 0;
        
        switch (ch) {
            
            case 1:
            for (int i = 90; i > 64; i--) {
                char c = (char)i;
                System.out.print(c);
                System.out.print(" ");
                count++;
                
                //Print 10 characters per line 
                if (count == 10) {
                    System.out.println();
                    count = 0;
                }
            }  
            break;
            
            case 2:
            for (int i = 97; i < 123; i++) {
                char c = (char)i;
                System.out.print(c);
                System.out.print(" ");
                count++;
                
                //Print 10 characters per line 
                if (count == 10) {
                    System.out.println();
                    count = 0;
                }
            }
            break;
            
            default:
            System.out.println("Incorrect Choice");
        }
    }
}

Output

Question 9

Write a program to input a letter. Find its ASCII code. Reverse the ASCII code and display the equivalent character.
Sample Input: Y
Sample Output: ASCII Code = 89
Reverse the code = 98
Equivalent character: b

import java.util.Scanner;

public class KboatASCIIReverse
{
   public static void main(String args[]) {
       Scanner in = new Scanner(System.in);
       System.out.print("Enter a letter: ");
       char l = in.next().charAt(0);
       
       int a = (int)l;
       System.out.println("ASCII Code = " + a);
       
       int r = 0;
       while (a > 0) {
           int digit = a % 10;
           r = r * 10 + digit;
           a /= 10;
       }
       
       System.out.println("Reversed Code = " + r);
       System.out.println("Equivalent character = " + (char)r);
   }
}

Output

Question 10

Write a menu driven program to display
(i) first five upper case letters
(ii) last five lower case letters as per the user's choice.
Enter '1' to display upper case letters and enter '2' to display lower case letters.

import java.util.Scanner;

public class KboatMenuUpLowCase
{
    public static void main(String args[]) {
        Scanner in = new Scanner(System.in);
        System.out.println("Enter '1' to display upper case letters");
        System.out.println("Enter '2' to display lower case letters");
        
        System.out.print("Enter your choice: ");
        int ch = in.nextInt();
        
        switch (ch) {
            case 1:
            for (int i = 65; i <= 69; i++)
                System.out.println((char)i);
            break;
            
            case 2:
            for (int i = 118; i <= 122; i++)
                System.out.println((char)i);
            break;
            
            default:
            break;
        }
    }
}

Output

Question 11

Using switch case statement, write a menu driven program to perform the following tasks:
(a) To generate and print the letters from A to Z along with their Unicode.
Letters Unicode
A           65
B           66
.....          ........
.....          ........
Z           90

(b) To generate and print the letters from z to a along with their Unicode.
Letters Unicode
z           122
y           121
.....          ........
.....          ........
a           97

import java.util.Scanner;

public class KboatLettersNUnicode
{
    public static void main(String args[])  {
        Scanner in = new Scanner(System.in);
        
        System.out.println("Enter 1 for A to Z with unicode");
        System.out.println("Enter 2 for z to a with unicode");
        
        System.out.print("Enter your choice: ");
        int ch = in.nextInt();
        
        switch (ch) {
            case 1:                
                System.out.println("Letters" + "\t" + "Unicode"); 
                for(int i = 65; i <= 90; i++) 
                    System.out.println((char)i + "\t" + i);    
                break;
            
            case 2:
                System.out.println("Letters" + "\t" + "Unicode");
                for (int i = 122; i >= 97; i--)   
                    System.out.println((char)i + "\t" + i); 
                break;
            
            default:
                System.out.println("Incorrect Choice");
        }
    }
}

Output

Question 12

Write a program in Java to display the following patterns:

(i)

A
ab
ABC
abcd
ABCDE

public class KboatPattern
{
    public static void main(String args[]) {
        for (int i = 65; i < 70; i++) {
            for (int j = 65; j <= i; j++) {
                if (i % 2 == 0)
                    System.out.print((char)(j+32));
                else
                    System.out.print((char)j);
            }
            System.out.println();
        }
    }
}

Output

(ii)

ZYXWU
ZYXW
ZYX
ZY
Z

public class KboatPattern
{
    public static void main(String args[]) {
        for (int i = 86; i <= 90; i++) {
            for (int j = 90; j >= i; j--) {
                System.out.print((char)j);
            }
            System.out.println();
        }
    }
}

Output

(iii)

ABCDE
ABC
A

public class KboatPattern
{
    public static void main(String args[]) {
        for (int i = 69; i >= 65; i = i - 2) {
            for (int j = 65; j <= i; j++) {
                System.out.print((char)j);
            }
            System.out.println();
        }
    }
}

Output

(iv)

PRTV
PRT
PR
P

public class KboatPattern
{
    public static void main(String args[]) {
        for (int i = 86; i >= 80; i = i - 2) {
            for (int j = 80; j <= i; j = j + 2) {
                System.out.print((char)j);
            }
            System.out.println();
        }
    }
}

Output

(v)

A*B*C*D*E*
A*B*C*D*
A*B*C*
A*B*
A*

public class KboatPattern
{
    public static void main(String args[]) {
        for(int i = 69; i >= 65; i--) {
            for (int j = 65; j <= i; j++) {
                System.out.print((char)j + "*");
            }
            System.out.println();
        }
    }
}

Output

(vi)

a a a a a
b b b b b
A A A A A
B B B B B

public class KboatPattern
{
    public static void main(String args[]) {
        int a = 97;
        for (int i = 1; i <= 4; i++) {
            for (int j = 1; j <= 5; j++) {
                System.out.print((char)a + " ");
            }
            a++;
            if (i == 2)
                a = 65;
            System.out.println();
        }
    }
}