android dialog opening and focusing on an edittext ? code example

Example: dialog with edittext android

AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);
 alertDialog.setTitle("PASSWORD");
 alertDialog.setMessage("Enter Password");

 final EditText input = new EditText(MainActivity.this);
 LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
     LinearLayout.LayoutParams.MATCH_PARENT,
     LinearLayout.LayoutParams.MATCH_PARENT);
 input.setLayoutParams(lp);
 alertDialog.setView(input);
 alertDialog.setIcon(R.drawable.key);

 alertDialog.setPositiveButton("YES",
     new DialogInterface.OnClickListener() {
         public void onClick(DialogInterface dialog, int which) {
             password = input.getText().toString();
             if (password.compareTo("") == 0) {
                 if (pass.equals(password)) {
                     Toast.makeText(getApplicationContext(),
                         "Password Matched", Toast.LENGTH_SHORT).show();
                     Intent myIntent1 = new Intent(view.getContext(),
                         Show.class);
                     startActivityForResult(myIntent1, 0);
                 } else {
                     Toast.makeText(getApplicationContext(),
                         "Wrong Password!", Toast.LENGTH_SHORT).show();
                 }
             }
         }
     });

 alertDialog.setNegativeButton("NO",
     new DialogInterface.OnClickListener() {
         public void onClick(DialogInterface dialog, int which) {
             dialog.cancel();
         }
     });

 alertDialog.show();
 }

 });