In java, the string is a sequence of characters and char is a single digit used to store variables. The char uses 2 bytes in java. In java, BufferedReader and InputStreamReader are used to read the input given by the user from the keyboard. Then readLine() is used for reading a line. The java.io package in java provides input and output through data streams, serialization, and the file system.
We can count the vowels in a string in two ways:
- Iterative
- Recursive
Examples:
Input: GeeksForGeeks Output: Total no of vowels in string are: 5 Input: ChETaN Output: Total no of vowels in string are: 2
Method 1: Iterative
Approach:
- We will traverse through the string’s characters in a for loop starting from index 0 till size-1.
- And check each character if it is a vowel or not and increment the count variable.
Below is the implementation of the above approach:
Java
// Java Program to Count Number of Vowels// in a String in a iterative wayimport java.io.*;public class vowel { public static void main(String[] args) throws IOException { String str = "GeeksForGeeks"; str = str.toLowerCase(); int count = 0; for (int i = 0; i < str.length(); i++) { // check if char[i] is vowel if (str.charAt(i) == 'a' || str.charAt(i) == 'e' || str.charAt(i) == 'i' || str.charAt(i) == 'o' || str.charAt(i) == 'u') { // count increments if there is vowel in // char[i] count++; } } // display total count of vowels in string System.out.println( "Total no of vowels in string are: " + count); }} |
Output
Total no of vowels in string are: 5
Method 2: Recursive
Approach:
- Check for the base condition if the length of the string is 1, then simply check for that single character if it is a vowel, then return 1 else return 0.
- For dividing the whole string into substrings to return the answer recursively, we will get the answer for the string starting from the first till second last character.
- And finally, return the above answer plus the answer for the check of last character (1 if it is vowel or 0 if it is not)
Below is the implementation of the above approach:
Java
// Java Program to Count Number of Vowels// in a String in a recursive wayimport java.io.*;class GFG { // isVowel() function returns 1 if the // character is a vowel and 0 if it is not static int isVowel(char chars) { if (chars == 'a' || chars == 'e' || chars == 'i' || chars == 'o' || chars == 'u') { return 1; } else { return 0; } } // recursive function to return the number // of characters in a string static int vowelno(String str, int l) { if (l == 1) { return isVowel(str.charAt(l - 1)); } return vowelno(str, l - 1) + isVowel(str.charAt(l - 1)); } public static void main(String[] args) throws IOException { String str = "BufferedOutput"; str = str.toLowerCase(); System.out.println( "Total number of vowels in string are:"); System.out.println(vowelno(str, str.length())); }} |
Output
Total number of vowels in string are: 6
Method 3: Using ArrayList and contains() method
Java
// Java Program to Count Number of Vowels// in a Stringimport java.io.*;import java.util.*;public class Main{ public static void main(String[] args)throws IOException { String str = "GeeksForGeeks"; str = str.toLowerCase(); int count = 0; String vow ="aeiou"; ArrayList<Character> vowels = new ArrayList<Character>(); for(int i=0;i<vow.length();i++) { vowels.add(vow.charAt(i)); } for (int i = 0; i < str.length(); i++) { if(vowels.contains(str.charAt(i))){ count++; } } // display total count of vowels in string System.out.println("Total no of vowels in string are: " + count); }} |
Output
Total no of vowels in string are: 5