Error with strings - At least one public class is required in main file, charAt involved

Question

Hi, when i try to execute this code i always get the error message from above, and i really want to know why, already tried to put a “public class XXXX” before the code, but not work anyway.

public static String invertirPalabras(String cadena) {
    cadena += " ";
    String palabra = "";
    String nuevaCadena = "";
    for (int i = 0; i < cadena.length(); i++) {
        palabra = cadena.charAt(i) + palabra;
        if (cadena.charAt(i) == ' ') {
            nuevaCadena += palabra;
            palabra = "";
        }
    }
    return nuevaCadena.trim();
}

Answer 1

Since your class contains static  methods only (according to your question, the class has one static method ), the class must have “static” modifier, since it cannot be instantiated. Only classes with at least one not static method can be instantiated. The rule is valid for both: Java and C#.

So, I would suggest to rewrite this piece of code as follows:

public static class  Helper{ 

    public static String invertirPalabras(String cadena) { 

         cadena += " ";

         String palabra = "";

        String nuevaCadena = "";

        for (int i = 0; i < cadena.length(); i++) { 

           palabra = cadena.charAt(i) + palabra;

           if (cadena.charAt(i) == ' ') {

                 nuevaCadena += palabra; 

                  palabra = ""; 

        }

     }

     return nuevaCadena.trim();

  }

 }