Avichal solutions for Computer Applications [English] Class 10 ICSE chapter 2 - Library Classes [Latest edition]

State the data type and value of y after the following is executed: char x = 7; y = Character.isLetter(x); 

Write the output of the following program code:

char ch ;
int x=97;
do
{
ch=(char) x;
System.out.print(ch + “ ” );
if(x%10 == 0)
break;
++x;
}while(x<=100);

What will be the output when the following code segment is  executed?
String s = “1001”;
int x = Integer. valueOf(s);
double y = Double.valueOf(s);
System.out.println(“x=”+x);
System.out.println(“y=”+y); 

What will be the output when the following code segment is executed?

System.out.println(“The king said\”Begin at the beginning!\“to me.”);

Name any two wrapper classes.

Name the wrapper class of char type. 

Name the wrapper class of boolean type. 

State the package that contains the class:
BufferedReader

State the package that contains the class:

Scanner 

What is the data type that the following library function return?

isWhiteSpace(char ch)

What is the data type that the following library function return?

Math.random( )

State the values of n and ch. 

char c = 'A'
int n = c + 1;
char ch = (char)n;

State the method that converts a string to a primitive float data type. 

State the method that determines, if the specified character is an upper case character. 

What are library classes? 

Give an example of library classes.

Write a function to check whether a character is a blank or not.

Creating a program for pattern making is an important aspect of logical development. Kunal has tried to design a program for a pattern shown alongside. But, due to some confusion, he could not complete it and has left some places blank marked with ?1?, ?2?, ?3? and ?4? to be filled with appropriate value/ expression. The program is as shown below: 

class Pattern
{
     public static void main()
     {
       int a, b, p;
       p = ..........?1?.........;
       for (a = 5; a >= 1; a--)
       {
          for(............?2?...............)
          System.out.print((...?3?...)p);
          System.out.println();
          p = .....?4?......;
       }
     }
}

Based on the above discussion, answer the following questions:

1. What will be filled in the place marked with ?1?
   1. 65
   2. 82
   3. 90
   4. 122
2. What will be filled in the place marked with ?2?
   1. b = 1; b <= a; b++
   2. b = a; b < 90; b++
   3. b = 90; b > 65; b++
   4. b = 65; b <= 90; b++
3. What will be filled in the place marked with ?3?
   1. int
   2. char
   3. float
   4. double
4. What will be filled in the place marked with ?4?
   1. p + 2
   2. p * 2
   3. p++
   4. p − 2

A package contains: 

Each primitive data type belongs to a specific ______. 

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

The parselnt() function is a member of ______.

valueOf() function converts ______. 

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

Which of the following statements is true? 

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

______ is a collection of classes. 

By default, ______ package is imported in a Java program. 

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

The data type int is included in ______ wrapper class. 

Wrapper class uses first letter in ______ case. 

String data is converted to float type by using ______ function.

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

Each character oriented function uses a wrapper tag ______.

Java class library includes all the packages.

Wrapper classes belong to java.util package.

Array is a non-primitive data type. 

Class is a composite data type. 

Integer.toString() converts integer data to String. 

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

Find the output of the following program snippet:

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

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:

1. What is the name given to the packet containing a primitive data type?
2. What is the function used to convert a string data into integer type?
3. Name the term used to convert a primitive data into the object of its wrapper class.
4. What is the syntax to convert a string "24" into integer data type?

Write the purpose of the following function:

Float.parseFloat() 

Write the purpose of the following function:

Double.toString()

Write the purpose of the following function:

Integer.valueOf()

Write the purpose of the following function:

Character.isDigit()

Write the purpose of the following function:

Character.isWhitespace()

What is meant by a package? 

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

Define a wrapper class. 

Write a difference between the functions isUpperCase() and toUpperCase().

Differentiate between parselnt() and toString() functions.

Write one difference between primitive data types and composite data types.

int res = ‘A’; 

What is the value of res?

Name the package that contains wrapper classes. 

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

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

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

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

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

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 

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

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. 

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

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

Write a menu driven program to display

1. first five uppercase letters
2. last five lowercase letters as per the user's choice.
   Enter 1 to display uppercase letters and enter 2 to display lowercase letters. 

Using switch case statement, write a menu driven program to perform the following tasks:

1. To generate and print the letters from A to Z along with their Unicode. 
   Letters                              Unicode
   A                                        65
   B                                        66
   ..........                                  .........
   ..........                                  .........
   Z                                        90
2. To generate and print the letters from z to a along with their Unicode.
   Letters                               Unicode
   z                                          122
   y                                          121
   ..........                                    .........
   ..........                                    .........
   a                                          97

Write a program in Java to display the following pattern:

A
ab
ABC
abcd
ABCDE 

Write a program in Java to display the following pattern:

ZYXWU
ZYXW
ZYX
ZY
Z

Write a program in Java to display the following pattern:

ABCDE
ABC
A

Write a program in Java to display the following pattern:

PRTV
PRT
PR
P

Write a program in Java to display the following pattern:

A*B*C*D*E
A*B*C*D*
A*B*C*
A*B*
A* 

Write a program in Java to display the following pattern:

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