String Practice Programs

title: String Programs description: String ke important practice programs

1. String Reverse karo

java exampleWoHoTech

String reverse(String s) {
    return new StringBuilder(s).reverse().toString();
}

2. Palindrome Check

boolean isPalindrome(String s) { s = s.toLowerCase().replaceAll("[^a-z0-9]", ""); String rev = new StringBuilder(s).reverse().toString(); return s.equals(rev); }

3. Character Frequency Count

java exampleWoHoTech

void charFrequency(String s) {
    Map<Character, Integer> map = new LinkedHashMap<>();
    for (char c : s.toCharArray())
        map.put(c, map.getOrDefault(c, 0) + 1);
    map.forEach((k, v) -> System.out.println(k + ": " + v));
}

4. First Non-Repeating Character

java exampleWoHoTech

char firstNonRepeating(String s) {
    Map<Character, Integer> freq = new LinkedHashMap<>();
    for (char c : s.toCharArray())
        freq.put(c, freq.getOrDefault(c, 0) + 1);
    for (Map.Entry<Character, Integer> e : freq.entrySet())
        if (e.getValue() == 1) return e.getKey();
    return '\0';
}

5. Count Words in String

java exampleWoHoTech

int countWords(String s) {
    s = s.trim();
    if (s.isEmpty()) return 0;
    return s.split("\\s+").length;
}

6. Remove Duplicates from String

java exampleWoHoTech

String removeDuplicates(String s) {
    StringBuilder sb = new StringBuilder();
    Set<Character> seen = new LinkedHashSet<>();
    for (char c : s.toCharArray())
        if (seen.add(c)) sb.append(c);
    return sb.toString();
}

7. String Compression

String compress(String s) { StringBuilder sb = new StringBuilder(); int i = 0; while (i < s.length()) { char c = s.charAt(i); int count = 1; while (i + count < s.length() && s.charAt(i + count) == c) count++; sb.append(c).append(count); i += count; } return sb.length() < s.length() ? sb.toString() : s; } // "aabccc" → "a2b1c3"

title: String Programs description: String ke important practice programs

1. String Reverse karo

java exampleWoHoTech

String reverse(String s) {
    return new StringBuilder(s).reverse().toString();
}

2. Palindrome Check

boolean isPalindrome(String s) { s = s.toLowerCase().replaceAll("[^a-z0-9]", ""); String rev = new StringBuilder(s).reverse().toString(); return s.equals(rev); }

3. Character Frequency Count

java exampleWoHoTech

void charFrequency(String s) {
    Map<Character, Integer> map = new LinkedHashMap<>();
    for (char c : s.toCharArray())
        map.put(c, map.getOrDefault(c, 0) + 1);
    map.forEach((k, v) -> System.out.println(k + ": " + v));
}

4. First Non-Repeating Character

java exampleWoHoTech

char firstNonRepeating(String s) {
    Map<Character, Integer> freq = new LinkedHashMap<>();
    for (char c : s.toCharArray())
        freq.put(c, freq.getOrDefault(c, 0) + 1);
    for (Map.Entry<Character, Integer> e : freq.entrySet())
        if (e.getValue() == 1) return e.getKey();
    return '\0';
}

5. Count Words in String

java exampleWoHoTech

int countWords(String s) {
    s = s.trim();
    if (s.isEmpty()) return 0;
    return s.split("\\s+").length;
}

6. Remove Duplicates from String

java exampleWoHoTech

String removeDuplicates(String s) {
    StringBuilder sb = new StringBuilder();
    Set<Character> seen = new LinkedHashSet<>();
    for (char c : s.toCharArray())
        if (seen.add(c)) sb.append(c);
    return sb.toString();
}

String Practice Programs

1. String Reverse karo

2. Palindrome Check

3. Character Frequency Count

4. First Non-Repeating Character

5. Count Words in String

6. Remove Duplicates from String

7. String Compression

Continue learning this concept

String Practice Programs

1. String Reverse karo

2. Palindrome Check

3. Character Frequency Count

4. First Non-Repeating Character

5. Count Words in String

6. Remove Duplicates from String

7. String Compression

Continue learning this concept