> For the complete documentation index, see [llms.txt](https://educacion.gitbook.io/programacion/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://educacion.gitbook.io/programacion/exercicios-java/ud3-solucions/strings.md).

# Strings

```java
package EjerciciosStrings;

public class UtilidadesUsuario {

        public static int LON_CONTRASINAL = 10;

        public static int contadorCaracteres(String s, char c){
            int cont = 0;
            for (int i =0; i< s.length(); i++){
                if (s.charAt(i) == c)
                    cont++;
            }
            return cont;
        }

        public static String xerarContrasinal(){
            String res = "";
            for (int i=0; i<LON_CONTRASINAL; i++){
                int car = (int) (Math.random()*26);
                char letra = (char) ('a' + car);
                res += letra;
            }
            return res;
        }

        public static String xerarContrasinalSenRepetidos(){
            String res = "";
            int i = 0;
            while (i<LON_CONTRASINAL){
                int car = (int) (Math.random()*26);
                char letra = (char) ('a' + car);
                if (!res.contains(String.valueOf(letra))){
                    res+=letra;
                    i++;
                }
            }
            return res;
        }

        public static String ocultarContrasinal(String contrasinal) throws Exception{
            if (contrasinal.length()<3)
                throw new Exception("No se puede ocultar de forma correcta la contraseña");
            String res = "";
            for (int i = 0; i<contrasinal.length();i++){
                if (i<2 || (i==contrasinal.length()-1)){
                    res+=contrasinal.charAt(i);
                } else {
                    res+="*";
                }
            }
            return res;
        }

        public static int contadorPalabras(String cadena){
            int contador = 0;
            cadena = cadena.trim();
            if (cadena.length() == 0)
                return contador;
            contador = 1;
            for(int i = 0; i< cadena.length() -1 ; i++){
                if ((cadena.charAt(i) == ' ') && (cadena.charAt(i+1)!=' '))
                    contador++;
            }
            return contador;
        }


}

```

```java
public class App {
    public static void main(String[] args) {

        int num = UtilidadesUsuario.contadorCaracteres("abracadabra",'a');
        System.out.println("abracadabra ten " + num + " letras a");
        String cont =UtilidadesUsuario.xerarContrasinal();
        System.out.println("Contrasinal:" + cont);
        String cont2 = UtilidadesUsuario.xerarContrasinalSenRepetidos();
        System.out.println("Contrasinal sen repetidos:" + cont2);
        try {
            String contOculto = UtilidadesUsuario.ocultarContrasinal(cont2);
            System.out.println("Contrasinal sen repetidos oculto:" + contOculto);
        } catch (Exception e){
            System.out.println("Error: " + e.getMessage());
        }
        int conPal = UtilidadesUsuario.contadorPalabras("En un lugar de la mancha,  de cuyo  nombre no quiero acordarme a");
        System.out.println("Total de palabras:" + conPal);


    }
}

```


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