Android Question Replacing a string in a text file

[apty]

I tried the code below to replace a specific string in a text file. I am not getting any error but the replacement is not working. Please advice what i am doing wrong

mynewfile=File.ReadString(File.DirDefaultExternal&"/testr/","Mai.txt")
    mynewfile = mynewfile.Replace ("kliev", "jared")
    File.WriteString(File.DirDefaultExternal&"/testr/","Mai.txt",mynewfile)

 

[klaus]

What is not working ?

Put a breakpoint in the second line.
Check the content of mynewfile. Is the reading OK ?
Go one step further and check mynewfile again. Did the content change ?
Go one step further to save the file.
Add a new line reading the file back and check.

 

[ajk]

I have the same problem

Dim abc As String
abc= "aaa DO bbb"
abc.Replace("DO", "AAA")
Et3.Text=abc

and we habe Et3= "aaa DO bbb"

It seems to be .replace problem.

 

[klaus]

This is wrong:
abc.Replace("DO", "AAA")
but this works:
abc = abc.Replace("DO", "AAA")

 

[Erel]

This is a common mistake.

Remember that strings are immutable (unlike StringBuilder).
This means that the only way to change the string value referenced by abc is by assigning a new string to abc.

 

[Troberg]

Just to make it even clearer:

This code is correct:

abc = abc.Replace("DO", "AAA")

It does the replace and returns it, and we place it in a variable (which happens to be the same variable we started with).

This code is not correct:

abc.Replace("DO", "AAA")

It does the replace and returns it, but we do nothing with the return value, we just throw it away.

A very easy mistake to make, even if one knows it's wrong. The brain is a bit lazy sometimes, and tends to forget such details. I've done it myself, several times.

Perhaps an issue the compiler should raise a warning about? I can't see any reason under any circumstance to do it the wrong way, so a warning feels apropriate.

 

[ajk]

Great thanks !