Given string str, the task is to write a Java program to swap the pairs of characters of a string. If the string contains an odd number of characters then the last character remains as it is.
Examples:
Input: str = “Java”
Output: aJva
Explanation: The given string contains even number of characters. Therefore, we swap every pair of characters.
Input: str = “GeeksForGeeks”
Output: eGkeFsroeGkes
Explanation: The given string contains odd number of characters. Therefore, we swap every pair of characters and last character remains as it is.
1. Using String.toCharArray() Method
- Get the string to swap a pair of characters.
- Check if the string is null or empty then return the string.
- Converting the given string into a character array.
- Traverse the character array and swap the characters.
- Now, print the result.
Java
// Java program to swap pair// of characters of a string class GFG { // Function to swap pair of // characters of a string public static String swapPair(String str) { // Checking if string is null // or empty then return str if (str == null || str.isEmpty()) return str; // Converting the given string // into a character array char[] ch = str.toCharArray(); // Traverse the character array for (int i = 0; i < ch.length - 1; i += 2) { // Swapping the characters char temp = ch[i]; ch[i] = ch[i + 1]; ch[i + 1] = temp; } // Converting the result into a // string and return return new String(ch); } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksForGeeks"; // Print the result System.out.println(swapPair(str)); }} |
Output
eGkeFsroeGkes
2. Using StringBuffer.append() Method
- Get the string to swap a pair of characters.
- Check if the string is null or empty then return the string.
- Creating a StringBuffer object with a length of the string passed as a parameter.
- Traverse the string and append the characters in the StringBuffer object in reverse order.
- Check if the string contains an odd number of characters then append the last character into the StringBuffer object.
- Now, print the result.
Java
// Java program to swap pair// of characters of a string class GFG { // Function to swap pair of // characters of a string public static String swapPairs(String str) { // Checking if string is null // or empty then return str if (str == null || str.isEmpty()) return str; int len = str.length(); // Creating a StringBuffer object with // length of the string passed as a parameter StringBuffer sb = new StringBuffer(len); // Traverse the string and append // the character in the StringBuffer // object in reverse order for (int i = 0; i < len - 1; i += 2) { sb.append(str.charAt(i + 1)); sb.append(str.charAt(i)); } // Checking if the string has // odd number of characters // then append the last character // into StringBuffer object if (len % 2 != 0) { sb.append(str.charAt(len - 1)); } // Converting the StringBuffer // into the string and return return sb.toString(); } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksForGeeks"; // Print the result System.out.println(swapPairs(str)); }} |
Output
eGkeFsroeGkes
