Question

In java, write a program that asks the user to enter a character. Then pass the character to the following methods.

1. isVowel() – returns true if the character is a vowel
2. isConsonant() – returns true if the character is a consonant
3. changeCase() – if the character is lower case then change it to upper case and if the character is in upper case then change it to lower case. (return type: char)

Example output is given below:

Enter a character

a

a is a vowel

a is not a consonant

a is equivalent to A

test case: e, E, d, D

Note: Java represents character using Unicode encoding and ‘A’ to ‘Z’ is represented by numbers 65 to 90 and ‘a’ to ‘z’ is represented by numbers 97 to 122. So to convert ‘A’ to ‘a’ you need to add (97-65) to A and then cast it to Character type since the addition will change its type to integer.

You can use the following code to read a character from console. When you call charAt(i) method for any String it returns the character at index i. The index of first character is 0, the index of second character is 1 and so on.

Scanner input = new Scanner(System.in);

char ch =input.next().charAt(0);

Answer 1

Source code of the program and its working are given below.Comments are also given along with the code for better understanding.Screen shot of the code and output are also attached.If find any difficulty, feel free to ask in comment section. Please do upvote the answer.Thank you.

Working of the program

• Inside main() method isVowel(), isConsonant() methods are called to check the character is vowel or cosonant respectvely
• changeCase() method is called to change case of the given character
• isLower() method use a single if statement to compare the character with vowels a,e,i,o,u,A,E,I,O,U
• If the given character is match with any one of the vowel,the method will returns true
• isConsonant() check first the given character is vowel or not
• if yes,return false
• otherwise check if the character is any alphabet or not
• if yes,means it is a consonant, then return true
• In all other case,return false
• changeCase() method checks if the given character is lower case or not
• if yes,subtract 32 from the character to get corresponding upper case character
• Otherwise checks if the given character is upper case or not
• if yes,add 32 to the character to get corresponding lower case character

Source code

//importing Scanner class to read user input
import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        //declaring a character variable ch
        char ch;
        //creating Scanner object to read user input
        Scanner input=new Scanner(System.in);
        System.out.println("Enter the character: ");
        //reading user input
        ch=input.next().charAt(0);
        //checking the character is a vowel by calling isVowel() method
        if (isVowel(ch))
            System.out.println(ch+" is a vowel");
        else
            System.out.println(ch+" is not a vowel");
        //checking the character is a consonant by calling isConsonant() method
        if (isConsonant(ch))
            System.out.println(ch+" is a consonant");
        else
            System.out.println(ch+" is not a consonant");
        //calling changeCase() method to change the case of character
        System.out.println(ch+" is equivalent to "+changeCase(ch));
    }
    //isVowel() method definition
    public static boolean isVowel(char ch)
    {
        //checking if the character is any one of the vowels a,e,i,o,u,A,E,I,O,U
        if(ch=='a'|| ch=='e'||ch=='i'||ch=='o'||ch=='u'||
                ch=='A'||ch=='E'||ch=='I'||ch=='O'||ch=='U')
            return true;
        else
            return false;
    }
    //isConsonant() method definition
    public static boolean isConsonant(char ch)
    {
        //checking if the character is any one of the vowels a,e,i,o,u,A,E,I,O,U
        if(ch=='a'|| ch=='e'||ch=='i'||ch=='o'||ch=='u'||
                ch=='A'||ch=='E'||ch=='I'||ch=='O'||ch=='U')
            //if yes return false
            return false;
        //otherwise check if it is an alphabet
        else if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
            //if yes, means it is a consonant,then return true
            return true;
        //if none of the condition true,return false
        else
            return false;
    }
    //changeCase() method definition
    public static char changeCase(char ch)
    {
        //if character is lower case then subtract 32 to get corresponding upper case
        if(ch>='a'&&ch<='z')
            ch=(char)(ch-32);
        //if character is upper case then add 32 to get corresponding lower case
        else if(ch>='A'&&ch<='Z')
            ch=(char)(ch+32);
        return ch;
    }
}

Screen shot of the code

Screen shot of the output