Why Does String.Replace Not Work

Why does String.replace not work?

You did not assign it to test. Strings are immutable.

test = test.replace("KP", "");

You need to assign it back to test.

Java String replace not working

String is immutable, which means that the html reference doesn't change, rather the replace method returns a new String object that you have to assign.

html = html.replace(delimiter + entry.getKey()+ delimiter, entry.getValue());

Java string.replace not working as string.replaceAll

Your real problem

JSON isn't regular at all, you can't just go messing with it like this. You should use a real JSON parser, and whatever gave you this backslashified monstrosity is where the real bug lies. The problem you're facing here can be 'fixed', but your code will remain a fragile mess until you fix this underlying problem!

Your approach to SonarCloud

You shouldn't be using tools like this unless you understand what they do, and given that you ask this question with no idea as to why SonarCloud is even suggesting you replace replaceAll to replace, that sounds like this advice applies to you. Always read the reasoning behind a linting rule.

The problem

.replaceAll replaces each occurrence, but is regular expression based. .replace replaces each occurrence, and isn't - it just replaces the literal string you write. So, all you need to do is .replace("\\", ""). The replaceAll requires 4 backslashes, because that becomes a string with 2 backslashes, which is regexp-ese for '1 backslash'.

String.Replace() is not working as expected to replace weird chars in strings in C#

Change this:

DisplayName.Replace("'", "-").Replace("\"", "-");

To this:

DisplayName = DisplayName.Replace("'", "-").Replace("\"", "-");

Java String.replace not working

String#replace doesn't support regex, use String#replaceAll:

x = x.replaceAll(".+", "x");

python: why does replace not work?

String.replace(substr)

does not happen in place, change it to:

string = string.replace("http://","")

String.replace() not replacing all occurrences

You need to replace the trailing comma as well (if one exists, which it won't if last in the list):

str = str.replaceAll("\\b382,?", "");

Note \b word boundary to prevent matching "-,1382,-".

The above will convert:

382,111,382,1382,222,382

to:

111,1382,222

String replace doesn't appear to be working

Strings in Python are immutable. That means that a given string object will never have its value changed after it has been created. This is why an element assignment like some_str[4] = "x" will raise an exception.

For a similar reason, none of the methods provided by the str class can mutate the string. So, the str.replace method does not work the way I think you expect it to. Rather than modifying the string in place, it returns a new string with the requested replacements.

Try:

encrypted_str = encrypted_str.replace(encrypted_str[j], dec_str2[k], 2)

If you're going to be making many such replacements, it may make sense to turn your string into a list of characters, make the modifications one by one, then use str.join to turn the list back into a string again when you're done.

Android String.replace not working

String text;
text= "2:15";
if(text.contains(":"))
{
    replace(":","."); // Will not cause anything as String is immutable. 
}
Log.i("Tag",text);

Change to

String text;
text="2:15";
if(text.contains(":")){
   text = text.replace(":",".");
}
Log.i("Tag",text);

Read up on Strings and their immutable property.

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