Form cmd_calcular = new Form("Calcular");
       cmd_calcular.addCommand(Voltar);
       cmd_calcular.addCommand(Sair);
 // 1. cmd_calcular.append(new StringItem(null, "Entre c/ inteiro n:"));
       TextField vin = new TextField("Entre c/ inteiro n: ", "", 1, TextField.NUMERIC); // 2.
       cmd_calcular.setCommandListener(this);
 // 1. byte[] vbuf = {1,2,3,4,5};
 // 1. ByteArrayInputStream vin = new ByteArrayInputStream(vbuf,1,1);
 // 1. int vint = vin.read();
       int vint = Integer.parseInt(vin.getString()); // 2.
       cmd_calcular.append(new StringItem(null, " " + vint));
       cmd_calcular.append(new StringItem(null, "\nResultado n * n = " + (vint * vint)));
       mDisplay.setCurrent(cmd_calcular);