Filtrando caracteres

Em eletrônica os filtros passa-faixa ou passa-banda,
filtros passa-baixas e passa-altas,
são largamente utilizados em circuitos onde determinadas
frequências devem ser rejeitadas,
passando apenas só a frequência ideal exigida.
Fórmulas matemáticas são usadas para se obter
um cálculo exato das frequências ideais,
onde se envolve a bitola do fio esmaltado,
o número de espiras num bastão de ferrite,
seu tamanho e seu diâmetro.
Saudades deste tempo dos transmissores e
receptores didáticos que agente montava
a alegria era vê-los funcionando.
O código aqui proposto atua como um filtro
impedindo que caracteres que não seja "f" ou "m"
possam passar, existem várias maneiras de fazer isto,
más este é um método fácil e seguro.

Veja abaixo imagens do programa em execução:

Veja abaixo o código do programa:

import java.util.Scanner;

public class PROJETO {

     public static int  tam  = 20;

    public static void main ( String [ ] args ) {

         J jht = new J ( );

         jht.textbackground ( jht.WHITE );

         jht.Moldura ( ( short ) 1, ( short ) 24, ( short ) 2, ( short ) 78 );

         jht.title ( " " );

         char vet [ ] = new char [ tam ];

         int i, p = 0, cont;

         // ///////////////////////////////////////////////////////////////////

         do {

              jht.cls ( );

              jht.textcolor ( jht.LIGHTRED );

              jht.gotoxy ( ( int ) 32, ( int ) 3 );

              System.out.printf ( "FILTRANDO CARACTERES" );

              jht.textcolor ( jht.LIGHTBLUE );

              jht.gotoxy ( ( int ) 25, ( int ) 5 );

              System.out.printf ( "Qual o tamanho do array ? " );

              jht.textcolor ( jht.LIGHTRED );

              Scanner sc = new Scanner ( System.in );

              p = sc.nextInt ( );

              jht.textcolor ( jht.BLACK );

              jht.gotoxy ( ( int ) 25, ( int ) 9 );

              if ( p < 0 || p > tam ) {

                   System.out.printf ( "Número Acima de 0 e menor que %d ", tam );

                   jht.Sleep ( ( short ) 1800 );

                   jht.textcolor ( jht.LIGHTRED );

                   jht.gotoxy ( ( int ) 29, ( int ) 21 );

                   System.out.printf ( "PRESSIONE QUALQUER TECLA" );

                   jht.getche ( );

                   jht.cls ( );

              }

         } while ( ( p < 0 ) || ( p > tam ) );

         // ///////////////////////////////////////////////////////////////////

         for ( i = 0; i < p; i++ ) {

              do {

                   jht.cls ( );

                   jht.textcolor ( jht.LIGHTRED );

                   jht.gotoxy ( ( int ) 32, ( int ) 3 );

                   System.out.printf ( "FILTRANDO CARACTERES" );

                   jht.textcolor ( jht.LIGHTBLUE );

                   jht.gotoxy ( ( int ) 30, ( int ) 7 );

                   System.out.printf ( "Insira o " );

                   jht.textcolor ( jht.LIGHTRED );

                   jht.gotoxy ( ( int ) 38, ( int ) 7 );

                   System.out.printf ( " %do", i + 1 );

                   jht.textcolor ( jht.LIGHTBLUE );

                   jht.gotoxy ( ( int ) 42, ( int ) 7 );

                   System.out.printf ( " Caracter : " );

                   jht.textcolor ( jht.LIGHTRED );

                  ///////////////////////////////////////////////////

                   Scanner sc = new Scanner( System.in );

                   String c = sc.next();

                   vet [ i ] = c.charAt( 0 );

                   ///////////////////////////////////////////////////

                 if ( vet [ i ] == 'f' || vet [ i ] == 'F' ||

                  vet [ i ] == 'm' || vet [ i ] == 'M' ) {

                        break;

                   } else {

                        jht.textcolor ( jht.LIGHTBLUE );

                        jht.gotoxy ( ( int ) 30, ( int ) 11 );

                        System.out.printf ( "Só digite " );

                        jht.textcolor ( jht.LIGHTRED );

                        System.out.printf ( "f" );

                        jht.textcolor ( jht.LIGHTBLUE );

                        System.out.printf ( " ou" );

                        jht.textcolor ( jht.LIGHTRED );

                        System.out.printf ( " m " );

                   }

                   jht.Sleep ( ( short ) 1800 );

                   jht.textcolor ( jht.LIGHTRED );

                   jht.gotoxy ( ( int ) 29, ( int ) 21 );

                   System.out.printf ( "PRESSIONE QUALQUER TECLA" );

                   jht.getche ( );

              } while ( true );

         }

         // ////////////////////////////////////////

        cont = 0;

         for ( i = 0; i < tam; i = i + 1 ) {

              if ( vet [ i ] == 'f' || vet [ i ] == 'F' )

                   cont = cont + 1;

         }

         jht.textcolor ( jht.LIGHTBLUE );

         jht.gotoxy ( ( int ) 22, ( int ) 9 );

         System.out.printf ( "Total de caracteres " );

         jht.textcolor ( jht.BLACK );

         System.out.printf ( "f" );

         jht.textcolor ( jht.LIGHTBLUE );

         System.out.printf ( " digitados" );

         jht.textcolor ( jht.LIGHTRED );

         System.out.printf ( " %d", cont );

         jht.getche ( );

         cont = 0;

         for ( i = 0; i < tam; i = i + 1 ) {

              if ( vet [ i ] == 'm' || vet [ i ] == 'M' )

                   cont = cont + 1;

         }

         jht.textcolor ( jht.LIGHTBLUE );

         jht.gotoxy ( ( int ) 22, ( int ) 11 );

         System.out.printf ( "Total de caracteres " );

         jht.textcolor ( jht.BLACK );

         System.out.printf ( "m" );

         jht.textcolor ( jht.LIGHTBLUE );

         System.out.printf ( " digitados" );

         jht.textcolor ( jht.LIGHTRED );

         System.out.printf ( " %d", cont );

         // /////////////////////////////////////////

         jht.Sleep ( ( short ) 1800 );

         jht.textcolor ( jht.LIGHTBLUE );

         jht.gotoxy ( ( short ) 23, ( short ) 17 );

         System.out.printf ( "Por: " );

         jht.textcolor ( jht.LIGHTMAGENTA );

         System.out.printf ( "Samuel Lima" );

         jht.Sleep ( ( short ) 1800 );

         jht.textcolor ( jht.LIGHTRED );

         jht.gotoxy ( ( short ) 36, ( short ) 22 );

         System.out.printf ( "MUITO OBRIGADO" );

         jht.getche ( );

     }

}