Given a string str and a positive integer k, the task is to write a Java program to print the first k characters of the string. If the length of the string is less than k then print the string as it is.
Examples:
Input: str = “GeeksForGeeks”, k = 5
Output: Geeks
Explanation: The first k characters of the given string is ‘Geeks’.
Input: str = “Geeks”, k = 6
Output: Geeks
Explanation: The length of the given string is less than k. Therefore, we print the string as it is.
Method 1: Using string length
- Get the string and a positive integer k to print the first k characters of the string.
- Check if the string is null or empty then return null.
- Check if the string length is greater than k then get the first k characters of the string using str.substring(0, k).
- If the string length is less than k then return the string as it is.
- Now, print the first k characters of the string.
Below is the implementation of the above approach:
Java
// Java program to print first k// characters of the string class GFG { // Function to print first k // characters of the string public static String firstKCharacters(String str, int k) { // Check if the string is empty // or null then return null if (str == null || str.isEmpty()) return null; // Check if the string length // is greater than k, then // get the first k characters // of the string, otherwise // return the string as it is if (str.length() > k) return str.substring(0, k); else return str; } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksForGeeks"; // Given a positive integer k int k = 5; // Print the first k characters // of the string System.out.println( firstKCharacters(str, k)); }} |
Output
Geeks
Method 2: Without checking the size
- The idea is to use Math.min() function as an end index of the substring method.
- Find the minimum value between the length of the string and positive integer k.
- Get the substring from zero to the minimum of string length and k.
- Now, print the first k characters of the string.
Below is the implementation of the above approach:
Java
// Java program to print first k// characters of the string class GFG { // Function to print first k // characters of the string public static String firstKCharacters(String str, int k) { // Check if the string is // null or empty then // return null if (str == null || str.isEmpty()) return null; // Return the first k characters // of the string if the string // length is less than k, otherwise // return the string as it is return str.substring(0, Math.min(str.length(), k)); } // Driver Code public static void main(String args[]) { // Given String str String str = "GeeksForGeeks"; // Given a positive integer k int k = 5; // Print the first k characters // of the string System.out.println(firstKCharacters(str, k)); }} |
Output
Geeks
