BMI.java

package com.example.caltrack;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class BMI extends AppCompatActivity {

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

        //get TextViews
        bmiTextView = (TextView) findViewById(R.id.bmiTextView);

        //get Buttons
        calculateBmiButton = (Button) findViewById(R.id.calculateBmiButton);
        calculateBmiButton.setOnClickListener(calculateBmiButtonListener);

    }

    private TextView bmiTextView;//show the calculated BMR

    private Button calculateBmiButton;

    private void calculate() {
        double bmi = ( (double) Details.weight / ( (double) Details.height * (double) Details.height)) * 703;
        Log.d("MI","bmi=" + bmi);
        bmiTextView.setText(String.format("%.02f", bmi));
    }

    private View.OnClickListener calculateBmiButtonListener = new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            calculate();
        }
    };

}