Использовал StringBuilder
package com.javarush.task.task06.task0611;
import java.lang.StringBuilder;
import java.util.Scanner;
public class StringHelper {
public static String multiply(String s) {
String result = s;
StringBuilder sb = new StringBuilder(result);
sb.append(result);
sb.append(result);
sb.append(result);
sb.append(result);
result = sb.toString();
System.out.println(result);
return result;
}
public static String multiply(String s, int count) {
String result = s;
StringBuilder sb = new StringBuilder(s);
for (int i = 1; i < count; i++) {
sb.append(result);
}
System.out.println(sb.toString());
return result;
}
public static void main(String[] args) {
multiply("Amigo ");
multiply("Muchaches ", 10);
}
}