Android NumberShapes

package com.example.checkevenclass;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;


public class MainActivity extends AppCompatActivity {

    class NumberClass{
        int value;

        public boolean isTriangular()   //check for triangular number
        {
            if (value < 0)
                return false;
            int sum = 0;
            for (int n = 1; sum <= value; n++)
            {
                sum = sum + n;
                if (sum == value)
                    return true;
            }
            return false;
        }
        public boolean isPerfectSquare()    //check for perfect square
        {
            double sq = Math.sqrt(value);
            return ((sq - Math.floor(sq)) == 0);
        }
    }

    public void checkNumber(View view){

        EditText editText = (EditText) findViewById(R.id.editText);
        if (editText.getText().toString().trim().length() <=0 ){        //if editText is empty
            Toast.makeText(this, "Enter a number first", Toast.LENGTH_SHORT).show();
        }
        else {
            obj.value = Integer.parseInt(editText.getText().toString().trim());
            Toast.makeText(this, "Is Perfect square: " + obj.isPerfectSquare() + "\nIs triangular number: " + obj.isTriangular()
                    , Toast.LENGTH_SHORT).show();
        }
    }
    NumberClass obj = new NumberClass();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}