Replace a substring of arbitrary length

Question

I need to replace a substring of arbitrary length. For example between two spaces.

Example

String str = "Insert random message here";
// Manipulation
System.out.println(str);

// Outputs: Insert a message here

I have searched for a method in the String-class but I haven't found a useful one. (It might be because my bad English...)

What language are you using. Different languages have different solutions to this. — theGleep, Sep 19 '17 at 17:07
What are the actual criteria for identifying the text to be replaced? I see three spaces in your example text - which ones surround the text to be replaced? — Andrew Morton, Sep 19 '17 at 17:22
@ theGleep: Oops! Java. (Is there a way I can tell? but here?) — randy costanza, Sep 19 '17 at 17:37
@Andrew Morton: I want to be able to pick any word in any scentence and replace it with a different word. — randy costanza, Sep 19 '17 at 17:39

score 1 · Answer 1 · answered Sep 19 '17 at 17:12

1

System.out.println gives me a feeling that this is Java. You can use the object's replaceAll function to replace a string block/matching regex with another given string.

String str = "I am foo";
str.replaceAll("foo", "blah");
System.out.println(str);

Above code should print "I am blah".

answered Sep 19 '17 at 17:12

Parijat Purohit

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6
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Yes! But what if there's Another scentence with no "foo"? – randy costanza Sep 19 '17 at 17:35
It should do pretty much what's expected i.e. nothing. It basically matvhes a pattern and if found, replaces that with a given string. – Parijat Purohit Sep 20 '17 at 08:21

theGleep · Answer 2 · 2017-09-19T17:16:57.167

0

The most immediate solution is to use a pair of substring calls and concatenate the results:

String random = "random"
String str = "Insert random message here";

int nStart = str.indexOf(random);
int nEnd = nStart + random.length;

str = str.substr(0,nStart) + str.substr(nEnd);
System.out.println(str);

// Outputs: Insert a message here

note that my math is terrible, so the numbers are probably off by one or two!
Edited to use variables instead of "magic numbers"

Edited to add: I may not be using the same language as the OP, but hopefully it's close enough to be understood.

edited Sep 19 '17 at 17:16

answered Sep 19 '17 at 17:10

theGleep

1,179
8
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How would the OP get the numbers 6 and 13 in code, as *arbitrary length* implies? – Andrew Morton Sep 19 '17 at 17:14
But what if "random" doesn't exist in the scentence input? What if i have a random scentence and i just want to pick out ONE between two spaces? Doesn't this sollution imply that the Word "random " must be included? – randy costanza Sep 19 '17 at 17:34
Ah ... that's a bit of a different question. But I'll try to answer as clearly as possible. The variables are placeholders to be filled in. If you need to remove the second word, you can use an "indexOf" type function to find the first and second spaces. Or you could have a User Interface where the user would specify. The *cause* of abitrariness is directly related to how you will define start and end – theGleep Sep 19 '17 at 17:39
Hmmmm... Don't really get it. Do you have a simple example? – randy costanza Sep 19 '17 at 17:56

score 0 · Answer 3 · answered Sep 19 '17 at 17:51

0

You can use replaceFirst with this regex \s(.*?)\s which mean match the first word between two spaces like this :

String str = "Insert random message here";
str = str.replaceFirst("\\s(.*?)\\s", " a ");
System.out.println(str);

Output

Insert a message here

answered Sep 19 '17 at 17:51

Youcef LAIDANI

55,661
15
90
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Intresting! Now we're getting somewhere... What if i want to change the word? Third? n:th? – randy costanza Sep 19 '17 at 17:54
@randycostanza in this case you can use split and replace the nth word i don't think this is possible with regex :) – Youcef LAIDANI Sep 19 '17 at 18:39

Replace a substring of arbitrary length

3 Answers3