Different Ways to Generate String by using Characters and Numbers in Java Last Updated : 05 Aug, 2021 Comments Improve Suggest changes Like Article Like Report Given a number num and String str, the task is to generate the new String by extracting the character from the string by using the index value of numbers. Examples: Input: str = “GeeksforGeeks” num = 858 Output: GfG Explanation: The 8th, 5th, and 8th position of the characters are extracting from the given string and generate a new string. Input: str = “Java” num = 12 Output: The 1st and 2nd position of the characters are extracting from the given string and generate a new string. Method 1: Using Two Traversals Get the string and number to generate a new string.Initialize a variable that stores the final answer.Converting the given number into the string.Traverse the loop from start to end.Getting the last digit of the number and add kth position character into the variable answer.Traverse the loop in the reverse order and adding the jth position character into the variable finalAnswer.Now, print the result. Java // Java program to generate String by using // Strings and numbers class GFG { // Function to generate the new String public static String generateNewString(String str, int num) { // Initialize a variable that // stores the final answer. String finalAnswer = ""; String answer = ""; // Converting the given numbers // into string String index = String.valueOf(num); // Traverse the loop from start to end for (int i = 0; i < index.length(); i++) { // Getting last digit of numbers int k = num % 10; // Adding kth position character // into the variable answer answer = answer + str.charAt(k); num = num / 10; } // Traverse the loop in reverse order for (int j = answer.length() - 1; j >= 0; j--) { // Adding jth position character // into the variable finalAnswer finalAnswer = finalAnswer + answer.charAt(j); } // Return the finalAnswer return finalAnswer; } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksforGeeks"; // Given Number num int num = 858; // Printing the result System.out.println(generateNewString(str, num)); } } OutputGfG Method 2: Using One Traversal Get the string and number to generate a new string.Initialize a variable that stores the result.Converting the given number into the string.Traverse the loop from start to end.Get the right index and adding kth position character into the result.Now, print the result. Java // Java program to generate String by using // Strings and numbers class GFG { // Function to generate the new String public static String generateNewString(String str, int num) { // Initialize a variable that // stores the result. String result = ""; // Converting the given numbers // into the string String index = String.valueOf(num); // Traverse the loop from start to end for (int i = 0; i < index.length(); i++) { // Getting the right index int k = index.charAt(i) - 48; // Adding kth position character // into the result result = result + str.charAt(k); } // Return result return result; } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksforGeeks"; // Given Number num int num = 858; // Printing the result System.out.println(generateNewString(str, num)); } } OutputGfG Time Complexity: O(N) Comment More infoAdvertise with us Next Article Different Ways to Generate String by using Characters and Numbers in Java P prasanthcrmp Follow Improve Article Tags : Misc Strings Java DSA strings +1 More Practice Tags : JavaMiscStringsStrings Similar Reads Difference between String and Character array in Java Unlike C/C++ Character arrays and Strings are two different things in Java. 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