How do I make multi replace() java

Question

I have a string with \r\n, \r, \n or \" characters in it. How can I replace them faster?

What I already have is:

String s = "Kerner\\r\\n kyky\\r hihi\\n \\\"";
System.out.println(s.replace("\\r\\n", "\n").replace("\\r", "").replace("\\n", "").replace("\\", ""));

But my code does not look beautiful enough. I found on the Internet something like:

replace("\\r\\n|\\r|\\n|\\", "")

I tried that, but it didn't work.

When you say "more effective/faster/performancer", what do you mean by "more effective" and "performancer"? — khelwood, Feb 08 '17 at 16:15
Should be fairly easy to do using StringBuilder and charAt() with the original string — ControlAltDel, Feb 08 '17 at 16:19
`but that doesnt works` ... what do you mean by this? Your regex pattern correctly matches your current logic. — Tim Biegeleisen, Feb 08 '17 at 16:20
@Tim Biegeleisen, that part what i found in internet doesnt work with ' replaceAll("\\r\\n|\\r|\\n|\\", "");' returned Kerner\r\n kyky\r hihi\n \" — sausagerus, Feb 08 '17 at 17:11
@khelwood, I mean for equal funtion in java that can works faster. — sausagerus, Feb 08 '17 at 17:11
@sausagerus So by "more effective/faster/performancer" you just mean "faster" — khelwood, Feb 09 '17 at 09:04
@khelwood, exactly ))) But I found out that 4 * replaceAll() works faster. Its looks ugly but quickly. — sausagerus, Feb 09 '17 at 09:30

Haifeng Zhang · Accepted Answer · 2017-02-08T16:47:36.927

1

You can wrap it in a method, put /r/n, /n and /r in a list. iterate the list and replace all such characters and return the modified string.

public String replaceMultipleSubstrings(String original, List<String> mylist){
    String tmp = original;
    for(String str: mylist){
        tmp = tmp.replace(str, "");
    }
    return tmp;
}

Test:

mylist.add("\\r");
mylist.add("\\r\\n");
mylist.add("\\n");
mylist.add("\\");  // add back slash

System.out.println("original:" + s);
String x = new Main().replaceMultipleSubstrings(s, mylist);
System.out.println("modified:" + x);

Output:

original:Kerner\r\n kyky\r hihi\n \"
modified:Kerner kyky hihi "

edited Feb 08 '17 at 16:47

answered Feb 08 '17 at 16:18

Haifeng Zhang

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Thank you its works. Your method deleted all sign what i do not need. I recive 31000entries from DB and it is a little bit slower now, due for-loop what it goes 4 times for each entries. – sausagerus Feb 08 '17 at 21:33

Tim Biegeleisen · Answer 2 · 2017-02-08T16:23:50.127

I don't know if your current replacement logic be correct, but it says now that either \n, \r, or \r\n gets replaced with empty string, and backslash also gets replaced with empty string. If so, then you can try the following regex replace all:

String s = "Kerner\\r\\n kyky\\r hihi\\n \\\"";
System.out.println(s.replaceAll("\\r|\\n|\\r\\n|\\\\", ""));

One problem I saw with your attempt is that you are calling replace(), not replaceAll(), so it would only do a single replacement and then stop.

Adam · Answer 3 · 2017-02-08T17:27:00.683

0

String.replaceAll() can be used, in your question you tried to use String.replace() which does not interpret regular expressions, only plain replacement strings...

You also need to escape the \\ again, i.e. \\\\ instead of \\

String s = "Kerner\\r\\n kyky\\r hihi\\n \\\"";
System.out.println(s.replaceAll("\\\\r|\\\\n|\\\\\"", ""));

Output

Kerner kyky hihi

Note the differences between String.replaceAll() and String.replace()

String.replaceAll()

Replaces each substring of this string that matches the given regular expression with the given replacement.

String.replace()

Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.

edited Feb 08 '17 at 17:27

answered Feb 08 '17 at 16:20

Adam

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Not my downvote, but `String#replace()` doesn't need to double escape the backslash, q.v. [here](http://stackoverflow.com/questions/1701839/string-replaceall-single-backslashes-with-double-backslashes). – Tim Biegeleisen Feb 08 '17 at 16:24
@TimBiegeleisen I get this without escaping... Exception in thread "main" java.util.regex.PatternSyntaxException: Unexpected internal error near index 12 \r\n|\r|\n|\ ^ – Adam Feb 08 '17 at 16:25
You don't get it, you're calling `replaceAll()`, the OP is calling `replace()`. – Tim Biegeleisen Feb 08 '17 at 16:26
@TimBiegeleisen I can see that, but he is calling replace() because he believes replace() interprets regex, but it does not... – Adam Feb 08 '17 at 16:27
Actually I think it does in some cases. I have countered the downvote on the grounds that your answer may be right, though with a wrong explanation. – Tim Biegeleisen Feb 08 '17 at 16:28
@Adam, I want to delete all \r\n carriage-return from my string. Your code deleted all "\" sign – sausagerus Feb 08 '17 at 17:14
@sausagerus Apologies, I misread your question... your original code contains .replace("\\", "") which does the same... it removes the \ characters...Answer updated – Adam Feb 08 '17 at 17:23

score -1 · Answer 4 · answered Feb 08 '17 at 16:15

-1

Use a regular expression if you want to do all the replaces in one go. http://www.javamex.com/tutorials/regular_expressions/search_replace.shtml

answered Feb 08 '17 at 16:15

odin

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Not helpful. The OP needs a fix, not a reference. – nicomp Feb 08 '17 at 16:17
@nicomp Does OP want me to write the regex for him? I assume he can do so himself. – odin Feb 08 '17 at 16:18
1

You may assume anything but your answer is not an answer. – nicomp Feb 08 '17 at 16:19
@nicomp OP asked how to do all the replaces at once. I gave a way to do so and a link with a tutorial showing exactly how to use that answer.... – odin Feb 08 '17 at 16:20
2

@odin A link, though it may be useful, is not an answer. – khelwood Feb 08 '17 at 16:26

How do I make multi replace() java

4 Answers4