Remove character from string in Kotlin

Question

I am trying to create an Android calculator which uses strings in Kotlin. I do not know how to delete a comma (or the negative) if it already contains one.

Here is my code which adds the comma correctly but doesn't delete it if the user clicks again:

if (!buClickValue.contains(".")) {
    buClickValue += "."
} else {
    buClickValue.replace(".", "")
}

You say you are trying to add/remove comma, yet your code implies you are adding/removing dot. — Tim Biegeleisen
– Tim Biegeleisen, Commented Mar 18, 2018 at 3:14
Sorry my fault. If you look at the code you can see that if there is no "." in the string, it should add one to the string, but if there already is one, he should remove it. — Marcus Mondel
– Marcus Mondel, Commented Mar 18, 2018 at 3:20
My question is how do I remove the "."? // I added my git to the question, maybe that helps — Marcus Mondel
– Marcus Mondel, Commented Mar 18, 2018 at 3:23
Replace is not the good way to remove a char or sequence in a string: use filter in place of replace — Luc-Olivier
– Luc-Olivier, Commented Nov 1, 2019 at 0:51

Ameya Pandilwar · Accepted Answer · 2018-03-18 03:33:37Z

98

The replace() method is designed to return the value of the new String after replacing the characters. In your case, the value obtained after replacing the characters is never reassigned back to the original variable.

Specifically in your else clause, the line should be changed to -

buClickValue = buClickValue.replace(".", "")

answered Mar 18, 2018 at 3:33

Ameya Pandilwar

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1 Comment

Marcus Mondel Over a year ago

Thank you very much, that solved my problem and explained it well!

Luc-Olivier · Accepted Answer · 2022-03-26 20:27:27Z

19

The more logical technic is not to replace but to filter

buClickValue = buClickValue.filterNot { it == "."[0] }

or

buClickValue = buClickValue.filterNot { it == '.' }

Or to extend

filtered = ".,;:"

buClickValue = buClickValue.filterNot { filtered.indexOf(it) > -1 }

edited Mar 26, 2022 at 20:27

answered Oct 26, 2019 at 9:34

Luc-Olivier

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7 Comments

Luc-Olivier Over a year ago

The 1st exemple didn't compile anymore. I added ".get(0)"

Sakiboy Over a year ago

This should be preferred over the accepted answer. Nice answer!

Alessandro Scarozza Over a year ago

why not just ".filterNot { it == '.' }"

YUSMLE Over a year ago

@Xan You will see a lint error that says "Operator == cannot be applied to Char and String".

Luc-Olivier Over a year ago

@YUSMLE you spiked to @ Xan about my solution or???

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