Implementing the PasswordScreen class

This message asks the user for a password and forwards it to the main SATSAMIDlet class for message decryption.

To create the class:

1. Assign the class to the package satsa and import the required classes.

   package satsa;
   
   import javax.microedition.lcdui.Command;
   import javax.microedition.lcdui.CommandListener;
   import javax.microedition.lcdui.Displayable;
   import javax.microedition.lcdui.Form;
   import javax.microedition.lcdui.TextField;

2. Create the class by extending Form and implementing CommandListener.

   // Shows a password field used to decrypt a message
   class PasswordScreen
     extends Form
     implements CommandListener
   {
     private final SATSAMIDlet midlet;
     private final Command commandBack =
       new Command("Back", Command.BACK, 1);
     private final Command commandDecrypt =
       new Command("Decrypt", Command.ITEM, 1);
     private int index;
     TextField passwordField;
   
     PasswordScreen(SATSAMIDlet midlet)
     {
       super(null);
       this.midlet = midlet;
       createForm();
     }
     
     public void commandAction(Command c, Displayable d)
     {
       if (c==commandBack)
       {
         midlet.showEncryptedMessage(index);
       }
       if (c==commandDecrypt)
       {
         midlet.showDecryptedMessage(index,
             passwordField.getString());
       }
     }
   
     void setIndex(int index)
     {
       this.index = index;
       createForm();
     }
   
     private void createForm()
     {
       deleteAll();
       setTitle("Enter password to decrypt.");
       passwordField = new TextField("Password",
           "",
           16,
           TextField.PASSWORD);
       append(passwordField);
       addCommand(commandBack);
       addCommand(commandDecrypt);
       setCommandListener(this);
     }
   }