Java – How to remove line breaks from a file in Java

javaline-breaksnewlinestring

How can I replace all line breaks from a string in Java in such a way that will work on Windows and Linux (ie no OS specific problems of carriage return/line feed/new line etc.)?

I've tried (note readFileAsString is a function that reads a text file into a String):

String text = readFileAsString("textfile.txt");
text.replace("\n", "");

but this doesn't seem to work.

How can this be done?

Best Solution

You need to set text to the results of text.replace():

String text = readFileAsString("textfile.txt");
text = text.replace("\n", "").replace("\r", "");

This is necessary because Strings are immutable -- calling replace doesn't change the original String, it returns a new one that's been changed. If you don't assign the result to text, then that new String is lost and garbage collected.

As for getting the newline String for any environment -- that is available by calling System.getProperty("line.separator").

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Java – How to efficiently iterate over each entry in a Java Map

Map<String, String> map = ...
for (Map.Entry<String, String> entry : map.entrySet()) {
    System.out.println(entry.getKey() + "/" + entry.getValue());
}

On Java 10+:

for (var entry : map.entrySet()) {
    System.out.println(entry.getKey() + "/" + entry.getValue());
}

Python – How to remove a trailing newline

Try the method rstrip() (see doc Python 2 and Python 3)

>>> 'test string\n'.rstrip()
'test string'

Python's rstrip() method strips all kinds of trailing whitespace by default, not just one newline as Perl does with chomp.

>>> 'test string \n \r\n\n\r \n\n'.rstrip()
'test string'

To strip only newlines:

>>> 'test string \n \r\n\n\r \n\n'.rstrip('\n')
'test string \n \r\n\n\r '

In addition to rstrip(), there are also the methods strip() and lstrip(). Here is an example with the three of them:

>>> s = "   \n\r\n  \n  abc   def \n\r\n  \n  "
>>> s.strip()
'abc   def'
>>> s.lstrip()
'abc   def \n\r\n  \n  '
>>> s.rstrip()
'   \n\r\n  \n  abc   def'

Best Solution

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Python – How to remove a trailing newline

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