Vowels in a String

Using if-else statement

Method

• Convert the String to Upper Case
• Check every character of the String whether it is a vowel or not, using if statement
• Print the result accordingly

The following program explains the use of if-else statement in order to find vowels in a String :

public class Ninja {
    public static void main(String ar[])
    {
        String s="Coding Ninjas";
        String str=s.toUpperCase(); 	//Changing all the Characters to Upper Case
        int vowels=0;
        for(int i=0;i<str.length();i++)
        {
            if(str.charAt(i)=='A' || str.charAt(i)=='E' || str.charAt(i)=='I'|| str.charAt(i)=='O' || str.charAt(i)=='U')
            {
                ++vowels; 		//if a vowel is found, it gets incremented
            }
        }
        if(vowels==0)
            System.out.println("There are No Vowels in "+ str );
        else
           System.out.println("There are "+vowels+" Vowels in "+ s );
    }
}

You can also try this code with Online Java Compiler

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File name : Ninja.java

Output :

There are 4 Vowels in Coding Ninjas

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Using Switch-case statement

Method

• Convert the String to UpperCase
• Check every character of the String whether it is a vowel or not, using Switch Case statement
• Print the result accordingly

The following program explains the use of Switch-case statement in order to find vowels in a String :

public class Ninja {
 public static void main(String ar[])
    {
        String s="Coding Ninjas";
        String str=s.toUpperCase(); 	//Changing all the Characters to Upper Case
        int vowels=0;
        for(int i=0;i<str.length();i++)
        {
            switch(str.charAt(i))
            {
                case 'A' : vowels++; break;
                case 'E' : vowels++; break;
                case 'O' : vowels++; break;
                case 'I' : vowels++; break;
                case 'U' : vowels++; break;
            }
        }
         if(vowels==0)
            System.out.println("There are No Vowels in "+ str );
        else
           System.out.println("There are "+vowels+" Vowels in "+ s );
    }
}

You can also try this code with Online Java Compiler

Run Code

File name : Ninja.java

Output :

There are 4 Vowels in Coding Ninjas

You can also try this code with Online Java Compiler

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Using if-else statement in a Method

Method

• Define a Method with the original String as parameter and return value.
• Create a new String inside it.
• Convert the String to UpperCase
• Check every character of the String, whether it is a vowel or not, using if-else statement.
• Return the new String from the Method.
• Call the function in the main() Method.

The following program explains the use of if-else statement in a user-defined method in order to find vowels in a String :

public class Ninja {
    public static int find_vowels(String s)
    {
        String str=s.toUpperCase(); 	//Changing all the Characters to Upper Case
        int vowels=0;
        for(int i=0;i<str.length();i++)
        {
            if(str.charAt(i)=='A' || str.charAt(i)=='E' || str.charAt(i)=='I'|| str.charAt(i)=='O' || str.charAt(i)=='U')
            {
                ++vowels; 			//if a vowel is found, it gets incremented
            }
        }
        return vowels;
    }
    public static void main(String ar[])
    {
        String str="Coding Ninjas";
        int vowels=find_vowels(str); //Calling the function
        if(vowels==0)
            System.out.println("There are No Vowels in "+ str );
        else
           System.out.println("There are "+vowels+" Vowels in "+ str );  
        
    }
}

You can also try this code with Online Java Compiler

Run Code

File name : Ninja.java

Output :

There are 4 Vowels in Coding Ninjas

You can also try this code with Online Java Compiler

Run Code

Try it by yourself on Java Online Compiler.

Also check out Addition of Two Numbers in Java here.

FAQs

1. Are Strings in Java mutable?
   No, Strings in Java are immutable.
    
2. What is an if-else statement ? 
   In an if-else statement, if a particular condition is true, it executes a block of code. Another block of code can be performed if the condition is false.
    
3. What is the Average Time Complexity of finding vowels in a string?
   The Time Complexity of finding vowels in a string is O(n).

Key Takeaways

In this article, we have extensively discussed finding vowels in a string and their implementation in Java. The article explains the different approaches used to find vowels in a string in Java. The use of if-else statements and switch-case statements are explained. There are many more approaches, but these are the most efficient in terms of time and space.

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Happy Coding!