CODEWITHSUNDEEP
androidarithmetic-expressions
user3660378
user3660378

Reputation:

Arithmetic Operation

enter image description here

hello guys I am having this problem. When I enter a score in the editText, I want the app to generate the equivalent in the Textview(w/ red box). But the app crashes with this code.

private void calculateEquivalent(){
        double x , y;
        y = Double.valueOf(total_score.toString());
        x = Double.valueOf(editScore.getText().toString());

        if (x >= y * 0.65){
            double equivalent = (Math.round((100 + (72 * (x - y)) / y)));
            String equi = String.valueOf(equivalent);
            textEquivalent.setText(equi);
        } else {
            double equivalent = (Math.round((75 + (23 * (x - y * 0.65)) / y)));
            String equi = String.valueOf(equivalent);
            textEquivalent.setText(equi);
        }
    }

Upvotes: 3

Views: 119

Answers (5)

user3660378
user3660378

Reputation:

Thanks a lot guys without your suggestions I probably stuck in this problem :) and then I've come up with this

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

        TextWatcher inputTextWatcher = new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

            }

            @Override
            public void afterTextChanged(Editable s) {
                calculateEquivalent();
            }
        };
        editScore.addTextChangedListener(inputTextWatcher);

    }

private void calculateEquivalent(){
        try {
            y = Double.parseDouble(total_score);
            x = Double.parseDouble(editScore.getText().toString());
            if (x >= y * 0.65){
                double equivalent = (Math.round((100 + (72 * (x - y)) / y)));
                String equi = String.valueOf(equivalent);
                textEquivalent.setText(equi);

            } else {
                double equivalent = (Math.round((75 + (23 * (x - y * 0.65)) / y)));
                String equi = String.valueOf(equivalent);
                textEquivalent.setText(equi);
            }
        }catch (Exception e){
            Toast.makeText(getApplicationContext(), "Please Enter a Number", Toast.LENGTH_LONG).show();
            e.printStackTrace();
        }

    }

Upvotes: 0

androgo
androgo

Reputation: 574

Hey @callmejeo the main problem with the function you wrote above is that you are coverting "NULL" values into String so one thing you can do is that to HANDLE exception.

 private void calculateEquivalent(){

       try{
            double x , y;
            y = Double.valueOf(total_score.toString());
            x = Double.valueOf(editScore.getText().toString());

            if (x >= y * 0.65){
                double equivalent = (Math.round((100 + (72 * (x - y)) / y)));
                String equi = String.valueOf(equivalent);
                textEquivalent.setText(equi);
            } else {
                double equivalent = (Math.round((75 + (23 * (x - y * 0.65)) / y)));
                String equi = String.valueOf(equivalent);
                textEquivalent.setText(equi);
            }
}
   catch(Exception e){
         Toast.makeText(this,"Please Enter some value",Toast.LENGTH_LONG).show();
   }
}

Upvotes: 0

user4571931
user4571931

Reputation:

As the error log suggests, you need to make sure that you have proper values before you start the calculation.

So before calling this function you need to check for below conditions:

try
        {
        if((total_score.toString() != null && !total_score.toString().isEmpty()) && (editScore.getText().toString()!=null && !editScore.getText().toString().isEmpty()))
            {
                y = Double.valueOf(total_score.toString());

                x = Double.valueOf(editScore.getText().toString()); //chances of getting a Numberformat exception if entered value is not a number

                calculateEquivalent();
            }
        }
        catch(NumberFormatException e)
        {
        //Toast.makeText(m_context, "You entered a wrong value,Please enter only numeric values", Toast.LENGTH_SHORT).show();   
          e.printStackTrace();
        }
        catch(Throwable e)
        {
          e.printStackTrace();
        }

Also in your calculateEquivalent(); method, you need to make sure that value of y should not be zero.

Hope this helps you :)

Upvotes: 0

omer727
omer727

Reputation: 7565

You have a problem when trying to convert empty string to a double. You should check first that the text field is not empty and that it doesn't contain characters by catching NumberFormatException

Upvotes: 0

Khang Doan
Khang Doan

Reputation: 436

The error is empty string when convert from string to double

In this code

y = Double.valueOf(total_score.toString());

x = Double.valueOf(editScore.getText().toString());

May be total_score.toString() or editScore.getText().toString() was empty

And what is type of total_score variable

Upvotes: 2

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