由于某些原因，我的输入验证不起作用。每次我把calculate放在“app”上，当它应该有一个错误，说我需要输入身高/体重时，它就会崩溃。当我输入数字时，它会计算。谢谢你的帮助：）。我是新来安卓工作室的。
这是我的计算java文件

public class BmiFrag extends Fragment implements View.OnClickListener {
Button BmiButton;
private  double weight1=0;
private  double height1=0;
public static EditText heightIn;
public static EditText weightIn;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View myView = inflater.inflate(R.layout.fragment_bmi, container, false);
   BmiButton = (Button) myView.findViewById(R.id.CalculateBmi);
    BmiButton.setOnClickListener(this);
    return myView;
}

    @Override
     public void onClick(View v) {
         switch (v.getId()) {

        case R.id.CalculateBmi:

            weightIn = (EditText)
           getActivity().findViewById(R.id.ETtweight);
            heightIn = (EditText) getActivity().findViewById(R.id.ETHeight);
               final TextView tv4 = (TextView) 
         getActivity().findViewById(R.id.TFDisplayBmi);
            String str1 = weightIn.getText().toString();
            String str2 = heightIn.getText().toString();

            float weight = Float.parseFloat(str1);
            float height = Float.parseFloat(str2) ;

            float bmiValue = calculateBMI(weight, height);

            String bmiInterpretation = interpretBMI(bmiValue);

            tv4.setText(String.valueOf(bmiValue + "-" + bmiInterpretation));

            if (TextUtils.isEmpty(str1)) {

                weightIn.setError("Please enter your weight");
                weightIn.requestFocus();
                return;
            }

            else if (TextUtils.isEmpty(str2)) {
                heightIn.setError("Please enter your height");
                heightIn.requestFocus();
                return;
            }

            break;

    }
    }

   private float calculateBMI(float weight, float height) {

  float bmi= (float) (weight/ (height*height)*4.88);

        float total= Math.round(bmi);

       return  total;
   }

    private String interpretBMI(float bmiValue) {

      if (bmiValue < 16) {
          return "Severely underweight";
      } else if (bmiValue < 18.5) {

        return "Underweight";
        } else if (bmiValue < 25) {

          return "Normal";
       } else if (bmiValue < 30) {

          return "Overweight";
       } else {
           return "Obese";

       }

   }

    @Override
   public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
   }

   @Override
   public void onDestroy() {

   }

  @Override
   public void onDetach() {
      super.onDetach();
  }

}