Android TextWatcher

Question

I am trying to implement TextWatcher to my application, but when I enter a number into the edit text which has text watcher on it it gives me error like this:

AndroidRuntime:at java.lang.StringToReal.invalidReal(StringToReal.java:63)
AndroidRuntime:at java.lang.StringToReal.parseDouble(StringToReal.java:267)
AndroidRuntime:at java.lang.Double.parseDouble(Double.java:301)

And this is the code inside the text watcher:

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

    myPercent = Double.parseDouble(s.toString());
    myPrice =  Double.parseDouble(priceShow.getText().toString());
    finalPrice = myPrice*(myPercent/100);
    priceAfterDiscount.setText(String.valueOf(finalPrice));
}

What number did you exacly enter? – Damian Kozlak Nov 15 '15 at 14:41 — Damian Kozlak, Nov 15 '15 at 14:41

score 1 · Answer 1 · edited May 23 '17 at 12:23

1

I think your edit text value is empty. check first if its empty or not, then do the calculation. use try catch to find exact problem. try this, link

edited May 23 '17 at 12:23

Community

1
1

answered Nov 15 '15 at 15:00

Swapnil Meshram

128
8

It was not empty actually Swapnil, I have tried the solution that Damian provided and it worked, but to be honest I don’t know why :) – Tano Nov 15 '15 at 15:03
Ok. Exact reason is given by Damian in comment. Hope you understand the reason. – Swapnil Meshram Nov 15 '15 at 15:06
you were kind of right now Damian explained the problem I didnt notice it – Tano Nov 15 '15 at 15:07

Damian Kozlak · Accepted Answer · 2015-11-15T14:53:54.410

0

First of all, add

android:inputType="number"
android:singleLine="true"

to your myPercent EditText.

Problem is probably that you are entering , instead of . as decimal separator.

Use

try { 
    if (!s.toString().equals("") && !priceShow.getText().toString().equals("")) {
        myPercent = Double.parseDouble(s.toString());
        myPrice =  Double.parseDouble(priceShow.getText().toString());
        finalPrice = myPrice*(myPercent/100);
        priceAfterDiscount.setText(String.valueOf(finalPrice));
    }
} catch (NumberFormatException e) {
    e.printStackTrace();
}

to prevent application from crashing.

edited Nov 15 '15 at 14:53

answered Nov 15 '15 at 14:46

Damian Kozlak

7,065
10
45
51

yes I have just tried it, it gives me this error message: System.out: java.lang.NumberFormatException: Invalid double: "" – Tano Nov 15 '15 at 14:49
thank you so much, it worked !!! Can you tell me where was the problem I am really curious :/ – Tano Nov 15 '15 at 14:58
`TextWatcher` detected change within `s`, so `onTextChanged` has been called, but `s` was probably still empty in this moment, so by making `Double.parseDouble(s.toString());` you trying to make `double` from empty `String` `""`. All I did is just adding `if` which prevents execution of this method if `String` is empty. – Damian Kozlak Nov 15 '15 at 15:03

Android TextWatcher

2 Answers2