Java: Concatenate a given string with itself of a given number of times

Last update on May 21 2025 12:50:14 (UTC/GMT +8 hours)

106. Repeat String N Times

Write a Java program to concatenate a given string with itself a given number of times.

Visual Presentation:

Sample Solution:

Java Code:

import java.util.Arrays;

public class Main {
    public static void main(String[] args) {
        String str1 = "PHP"; // Declare and initialize a string variable
        System.out.println("Original string: " + str1); // Display the original string
        String resultV1 = repeat_str(str1, 7); // Call the repeat_str method with str1 and 7 as arguments
        System.out.println("\nAfter repeating 7 times: " + resultV1); // Display the result of repeating str1 7 times
    }

    public static String repeat_str(String str1, int n) {
        // Check if the input string is null or empty
        if (str1 == null || str1.isEmpty()) {
            return ""; // Return an empty string
        }
        
        // Check if n is less than or equal to 0
        if (n <= 0) {
            return str1; // Return the original string as n is 0 or negative
        }
        
        // Check if multiplying the length of str1 by n will exceed the maximum size of a String
        if (Integer.MAX_VALUE / n < str1.length()) {
            throw new OutOfMemoryError("Maximum size of a String will be exceeded"); // Throw an error
        }
        
        StringBuilder x = new StringBuilder(str1.length() * n); // Create a StringBuilder to store the result
        // Repeat the string n times and append it to the StringBuilder
        for (int i = 1; i <= n; i++) {
            x.append(str1);
        }
        return x.toString(); // Return the final repeated string
    }
}

Sample Output:

Original string: PHP

After repeating 7 times: PHPPHPPHPPHPPHPPHPPHP

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Java program to generate a new string by repeating a base string n times without using the built-in repeat() method.
• Write a Java program to concatenate a string with itself a specified number of times using a loop.
• Write a Java program to form a composite string by appending multiple copies of a string.
• Write a Java program to repeat a string repeatedly and join the repetitions to form the final string.

Go to:

• Java String Exercises Home ↩
• Java Exercises Home ↩

PREV : Count Substring Occurrences.
NEXT : Count Character Occurrences.

Java Code Editor:

Improve this sample solution and post your code through Disqus