Number Shape App (New Algorithm)

NumberShape.java

public class MainActivity extends ActionBarActivity {

    class Number {
                double x;
                String message = "";

                public void numTest() {


                    {
                        double a = 8 * x + 1;
                        double b = Math.sqrt(x);

                        if (Math.sqrt(a)%1 == 0 && x % b == 0) {       // To check triangular of number x
                            message = "Triangular & Square";          // (8x+1) must be a square number

                        } else if (Math.sqrt(a)%1 == 0 && x % b != 0) {
                            message = "Triangular";
                        } else if (Math.sqrt(a)%1 != 0 && x % b == 0) {
                            message = "Square";

                        } else {
                            message = "Neither";
                        }
                    }
                    Toast.makeText(getApplicationContext(),message,Toast.LENGTH_LONG).show();
                }

    }
      public void onClickToCheck(View view) {
         String message;

         EditText input = (EditText) findViewById(R.id.inpt);
         if (input.getText().toString().isEmpty()) {
             message = "You haven't Entered any Numbers!";
             Toast.makeText(getApplicationContext(),message,Toast.LENGTH_LONG).show();
         }
         else {
         double D_input = Double.parseDouble(input.getText().toString());
         Number userNum = new Number();
         userNum.x = D_input;
         userNum.numTest();
         }
     }