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C

String Programs

String manipulation problems are among the most frequently asked in interviews, and practicing them builds comfort with Java's built-in String methods.

Why practice these?

String manipulation problems are among the most frequently asked in interviews, and practicing them builds comfort with Java's built-in String methods.

Program 1: Check if a String is a Palindrome

java
public class PalindromeCheck {
    public static void main(String[] args) {
        String text = "madam";
        String reversed = new StringBuilder(text).reverse().toString();

        System.out.println("Is palindrome: " + text.equals(reversed));
    }
}

Output:

Is palindrome: true

Program 2: Count Vowels in a String

java
public class CountVowels {
    public static void main(String[] args) {
        String text = "Java Programming";
        int count = 0;

        for (char ch : text.toLowerCase().toCharArray()) {
            if (ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u') {
                count++;
            }
        }
        System.out.println("Vowel count: " + count);
    }
}

Output:

Vowel count: 5

Program 3: Reverse Each Word in a Sentence

java
public class ReverseWords {
    public static void main(String[] args) {
        String sentence = "Java is fun";
        String[] words = sentence.split(" ");
        StringBuilder result = new StringBuilder();

        for (String word : words) {
            result.append(new StringBuilder(word).reverse()).append(" ");
        }
        System.out.println(result.toString().trim());
    }
}

Output:

avaJ si nuf

Key Points to Remember

  • StringBuilder's reverse() method is a quick way to reverse text without writing manual loop logic.
  • split() is commonly used to break a sentence into individual words for processing.
  • String problems are among the most common topics in coding interviews, so regular practice pays off.