4

My app is a quiz app, in it there's a part that spits out a percent of questions the user got correct after answering all the questions as a Toast.

The toast is showing up but the percentage is always coming up as 0.

I have some log messages just infront:

        Log.i("MainActivity", "Amount i got right "+Integer.toString(right));
        Log.i("MainActivity", "total is "+Integer.toString(total));

        Toast.makeText(this, "You answered " + (right/total)*100 + "% of questions correct", Toast.LENGTH_SHORT).show();

In the log it says "I/MainActivity: Amount i got right 4 total is 6"

Why is the toast percentage coming as 0??

here's the function:

    int i = 0;
    int total = mQuestionBank.length;
    check = true;
    right = 0;
    while (i<total && check){
        if(mQuestionBank[i].isAlreadyAnswered()){
            if(mQuestionBank[i].isAnswerTrue()){
                right+=1;
                check = true;
            }

        }else{
            check = false;
        }
        i++;
    }

    if(check) {
        double percent = (right / total) * 100;
        Log.i("MainActivity", "Amount i got right "+Integer.toString(right));
        Log.i("MainActivity", "total is "+Integer.toString(total));

        Toast.makeText(this, "You answered " + (right/total)*100 + "% of questions correct", Toast.LENGTH_SHORT).show();
    }else {
        int question = mQuestionBank[mCurrentIndex].getTextResId();
        mQuestionTextView.setText(question);
        mTrueButton.setEnabled(!mQuestionBank[mCurrentIndex].isAlreadyAnswered());
        mFalseButton.setEnabled(!mQuestionBank[mCurrentIndex].isAlreadyAnswered());
    }

The Toast says "You answered 0% of the questions correct"

SonhnLab
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1h1h1h1h1h1h1h
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3 Answers3

4

The code is OK . You just need a simple modification . Try this : 

double percent = (right*100)/total ;

or ,

double percent = ((double)right/total)*100 ;

Hope this will work .

Update :

Why your code was not working ?

As a example take right = 5 and total = 10 . As the variable right and true are integers so right/total will be 0 zero always because they will return a integer value and the value after . is not considered in integer value . To solve the problem you can take right and total as double variable or cast the right as double . And the first explained formula . ***Because right*100 = 500 and (right*100)/total = 500/10 = 50 .

Sudipta Basak
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  • Yea, the first one worked why doesn't the percent formula i have work though? – 1h1h1h1h1h1h1h Jul 06 '18 at 04:17
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    Because you used integers. When you divide integer 2 by integer 5 - you get integer 0, instead of float 0.2, and then you multilied it to 100. 0*100=0. Only at the end, it converted to double. To avoid this, don't mix up numbers of different types, or be sure to cast them to the correct float point type before division. – Eugene Kartoyev Jul 06 '18 at 04:22
  • @EugeneKartoyev ... Also explained that correctly . – Sudipta Basak Jul 06 '18 at 04:49
1

I guess you could just modify your formula slightly:

Toast.makeText(this, "You answered " + ((right*100)/total) + "% of questions correct", Toast.LENGTH_SHORT).show();

No need to use double unless you need more exact numbers.

John T
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0

I'm not sure try like this: 

`Toast.makeText(this, "You answered " + pecent + "% of questions correct", Toast.LENGTH_SHORT).show();`
Mani Vasagam
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