AlertDialog Input Text

I'd like to use AlertDialog as a Login or pin code or password dialog. Here is my code -

    AlertDialog.Builder alert = new AlertDialog.Builder(this);                 
alert.setTitle("Login");  
alert.setMessage("Enter Pin :");                

 // Set an EditText view to get user input   
 final EditText input = new EditText(this); 
 alert.setView(input);

    alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {  
    public void onClick(DialogInterface dialog, int whichButton) {  
        String value = input.getText().toString();
        Log.d( TAG, "Pin Value : " + value);
        return;                  
       }  
     });  

    alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {

        public void onClick(DialogInterface dialog, int which) {
            // TODO Auto-generated method stub
            return;   
        }
    });
            alert.show();

How to code that all input text will appear like ' *** ' - asterisk

I can't get my pin code value although it shows into asterisk. my code is below

    private void accessPinCode_2()
{
    LayoutInflater factory = LayoutInflater.from(this);
    final View textEntryView = factory.inflate(R.layout.dialog_login, null);
    AlertDialog.Builder alert = new AlertDialog.Builder(this);                 
    alert.setTitle("Login");  
 alert.setMessage("Enter Pin :");                
 alert.setView(textEntryView);

    alert.setPositiveButton("Ok", new DialogInterface.OnClickListener() {  
    public void onClick(DialogInterface dialog, int whichButton) {  
        //String value = input.getText().toString();
        EditText mUserText;
        mUserText = (EditText) textEntryView.findViewById(R.id.txt_password);
        String strPinCode = mUserText.getText().toString();
        Log.d( TAG, "Pin Value : " + strPinCode);
        return;                  
       }  
     });  

    alert.setNegativeButton("Cancel", n