Decimal place on a Double TextView

Question

Hi I'm new to Java Programming and I need some help. I'm making a calculation app and I'm struggling with how to use decimals with textview in my results page. Could anyone help

My code:

            double result1 = num1 + num2;
            double result2 = num1 / num2;
            double result3 = num1 * num2;


            setContentView(R.layout.activity_result);

            TextView plusResult = (TextView)findViewById(R.id.plus_result);
            plusResult.setText(Double.toString(result1));

            TextView divResult = (TextView)findViewById(R.id.div_result);
            divResult.setText(Double.toString(result2));

            TextView timesResult = (TextView)findViewById(R.id.times_result);
            timesResult.setText(Double.toString(result3));

            break;

Answer 1

Based on your comments, you want to limit the answer to two decimal places. The following change does this:

double result1 = Math.round((num1 + num2) * 100.0) / 100.0;
double result2 = Math.round((num1 / num2) * 100.0) / 100.0;
double result3 = Math.round((num1 * num2) * 100.0) / 100.0;

It would be better to add a helper function to round if you do this in many places throughout your application.

Answer 2

If you want to round to two decimal places, you could create a method like so:

private double round(double value){
    return  (Math.round(value * 100.0) / 100.0);
}

Multiply it by 100, round to a whole number, then divide by 100 to get exactly 2 decimal places. If you need more or less decimal places, you can change the 100's to different powers of 10.