//1. Reverse a String
import java.util.Arrays;
public class StringReverse {
public static void main(String[] args) {
String original = "welcome";
// Method 1 - Using length() and charAt()
String rev1 = "";
for (int i = original.length() - 1; i >= 0; i--) {
rev1 += original.charAt(i);
}
System.out.println("Method 1 - Reverse string: " + rev1);
// Method 2 - By converting string to char array
String rev2 = "";
char[] charArray = original.toCharArray(); // Convert string to character array
System.out.println("Character array: " + Arrays.toString(charArray)); // Display the character array
for (int i = charArray.length - 1; i >= 0; i--) {
rev2 += charArray[i];
}
System.out.println("Method 2 - Reverse string: " + rev2);
// Method 3 - Using StringBuffer
StringBuffer sb = new StringBuffer(original);
String rev3 = sb.reverse().toString();
System.out.println("Method 3 - Reverse string: " + rev3);
// Method 4 - Using StringBuilder
StringBuilder sbuilder = new StringBuilder(original);
String rev4 = sbuilder.reverse().toString();
System.out.println("Method 4 - Reverse string: " + rev4);
}
}
//2. Check if a String is Palindrome
public class PalindromeCheck {
public static void main(String[] args) {
String str = "madam";
String reversed = new StringBuilder(str).reverse().toString();
if (str.equals(reversed)) {
System.out.println(str + " is a palindrome.");
} else {
System.out.println(str + " is not a palindrome.");
}
}
}
//3. Count Vowels and Consonants
public class VowelConsonantCount {
public static void main(String[] args) {
String str = "hello";
int vowels = 0, consonants = 0;
str = str.toLowerCase();
for (char c : str.toCharArray()) {
if (c == 'a' || c == 'e' || c == 'i' || c == 'o' || c == 'u') {
vowels++;
} else {
consonants++;
}
}
System.out.println("Vowels: " + vowels);
System.out.println("Consonants: " + consonants);
}
}
//4. Find the Length of a String Without Using length() Method
public class StringLength {
public static void main(String[] args) {
String str = "hello";
int length = 0;
for (char c : str.toCharArray()) {
length++;
}
System.out.println("Length of String: " + length);
}
}
//5. Convert a String to Upper Case
public class ToUpperCase {
public static void main(String[] args) {
String str = "hello";
String upperCaseStr = str.toUpperCase();
System.out.println("Uppercase: " + upperCaseStr);
}
}
//6. Convert a String to Lower Case
public class ToLowerCase {
public static void main(String[] args) {
String str = "HELLO";
String lowerCaseStr = str.toLowerCase();
System.out.println("Lowercase: " + lowerCaseStr);
}
}
//7. Replace a Character in a String
public class ReplaceCharacter {
public static void main(String[] args) {
String str = "hello";
String replacedStr = str.replace('l', 'y');
System.out.println("Replaced String: " + replacedStr);
}
}
//8. Remove All White Spaces from a String
public class RemoveSpaces {
public static void main(String[] args) {
String str = "he llo world";
String noSpacesStr = str.replaceAll("\\s", "");
System.out.println("String without spaces: " + noSpacesStr);
}
}
//9. Check if Two Strings are Anagrams
import java.util.Arrays;
public class AnagramCheck {
public static void main(String[] args) {
String str1 = "listen";
String str2 = "silent";
char[] arr1 = str1.toCharArray();
char[] arr2 = str2.toCharArray();
Arrays.sort(arr1);
Arrays.sort(arr2);
if (Arrays.equals(arr1, arr2)) {
System.out.println(str1 + " and " + str2 + " are anagrams.");
} else {
System.out.println(str1 + " and " + str2 + " are not anagrams.");
}
}
}
//10. Split a String into an Array
import java.util.Arrays;
public class SplitString {
public static void main(String[] args) {
String str = "hello world";
String[] words = str.split(" ");
System.out.println(Arrays.toString(words));
}
}
//11. Remove a Specific Character from a String
public class RemoveCharacter {
public static void main(String[] args) {
String str = "hello";
String removedStr = str.replace("l", "");
System.out.println("String after removing 'l': " + removedStr);
}
}
//12. Concatenate Two Strings Without Using + Operator
public class ConcatenateStrings {
public static void main(String[] args) {
String str1 = "hello";
String str2 = "world";
String concatenatedStr = str1.concat(str2);
System.out.println("Concatenated String: " + concatenatedStr);
}
}
//13. Reverse Words in a Sentence
public class ReverseWords {
public static void main(String[] args) {
String str = "hello world";
String[] words = str.split(" ");
StringBuilder reversedStr = new StringBuilder();
for (int i = words.length - 1; i >= 0; i--) {
reversedStr.append(words[i]).append(" ");
}
System.out.println("Reversed Sentence: " + reversedStr.toString().trim());
}
}
