Replacing sub-string of a String with another String

Question

I have a String

String str = (a AND b) OR (c AND d)

I tokenise with the help of code below

String delims = "AND|OR|NOT|[!&|()]+"; // Regular expression syntax
String newstr = str.replaceAll(delims, " ");
String[] tokens = newstr.trim().split("[ ]+");

and get String[] below

[a, b, c, d]

To each element of the array I add " =1" so it becomes

[a=1, b=1, c=1, d=1]

NOW I need to replace these values to the initial string making it

(a=1 AND b=1) OR (c=1 AND d=1)

Can someone help or guide me ? The initial String str is arbitrary!

Community · Accepted Answer · 2017-05-23 11:48:48Z

2

This answer is based on @Michael's idea (BIG +1 for him) of searching words containing only lowercase characters and adding =1 to them :)

String addstr = "=1";
String str = "(a AND b) OR (c AND d) ";

StringBuffer sb = new StringBuffer();

Pattern pattern = Pattern.compile("[a-z]+");
Matcher m = pattern.matcher(str);
while (m.find()) {
    m.appendReplacement(sb, m.group() + addstr);
}
m.appendTail(sb);
System.out.println(sb);

output

(a=1 AND b=1) OR (c=1 AND d=1)

edited May 23, 2017 at 11:48

CommunityBot

11 silver badge

answered Aug 13, 2012 at 2:20

Pshemo

125k26 gold badges194 silver badges280 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Peter Lawrey Over a year ago

Please don't use a StringBuffer when you can use a StringBuilder.

Pshemo Over a year ago

@PeterLawrey Is it possible to use StringBuilder here?

Michael · Accepted Answer · 2012-08-13 02:21:40Z

2

Given:

String str = (a AND b) OR (c AND d);
String[] tokened = [a, b, c, d]
String[] edited = [a=1, b=1, c=1, d=1]

Simply:

for (int i=0; i<tokened.length; i++)
    str.replaceAll(tokened[i], edited[i]);

Edit:

String addstr = "=1";
String str = "(a AND b) OR (c AND d) ";
String delims = "AND|OR|NOT|[!&|() ]+"; // Regular expression syntax
String[] tokens = str.trim().split( delims );
String[] delimiters = str.trim().split( "[a-z]+"); //remove all lower case (these are the characters you wish to edit)

String newstr = "";
for (int i = 0; i < delimiters.length-1; i++)
    newstr += delimiters[i] + tokens[i] + addstr;
newstr += delimiters[delimiters.length-1];

OK now the explanation:

tokens = [a, b, c, d]
delimiters = [ "(" , " AND " , ") OR (" , " AND " , ") " ]

When iterating through delimiters, we take "(" + "a" + "=1".

From there we have "(a=1" += " AND " + "b" + "=1".

And on: "(a=1 AND b=1" += ") OR (" + "c" + "=1".

Again : "(a=1 AND b=1) OR (c=1" += " AND " + "d" + "=1"

Finally (outside the for loop): "(a=1 AND b=1) OR (c=1 AND d=1" += ")"

There we have: "(a=1 AND b=1) OR (c=1 AND d=1)"

edited Aug 13, 2012 at 2:21

answered Aug 13, 2012 at 0:36

Michael

3692 silver badges10 bronze badges

12 Comments

Michael Over a year ago

You could also keep track of the indices where you find all the tokens, and insert the desired string:

Pshemo Over a year ago

But what in case str = "(A AND B)"? You will get str = "(A=1 A=1ND B=1)"

Achilles Over a year ago

I can restrict str to be lower case, if there is not better solution ? how could a regex help in that case ? if u could add it to ur answer please

Michael Over a year ago

Let me put something together. It'll take a min.

Pshemo Over a year ago

+1 and this is little improved version of this answer. Hope you will like it.

|

W. B. Reed · Accepted Answer · 2012-08-13 00:29:06Z

1

How long is str allowed to be? If the answer is "relatively short", you could simply do a "replace all" for every element in the array. This obviously is not the most performance-friendly solution, so if performance is an issue, a different solution would be desireable.

answered Aug 13, 2012 at 0:29

W. B. Reed

1,6941 gold badge10 silver badges10 bronze badges

6 Comments

Achilles Over a year ago

I have built the Array ! I just need to put back the replaced elements of array into the initial string. Like I want to put [a=1, b=1, c=1, d=1] into string (a AND B) OR (c AND d) replacing a,b,c,d. do you get my point ?

W. B. Reed Over a year ago

yes, I'm saying for every element in the array, do str.replaceAll(tokens[i], tokens[i] + "=1").

Achilles Over a year ago

@Pshemo raised a really good point "But what in case str = "(A AND B)"? You will get str = "(A=1 A=1ND B=1)"

W. B. Reed Over a year ago

yeah, hadn't thought of that. Well, if you still wanted to go that route, you could use regex matching to say ONLY A and not "AND" but that seems like it's getting too complicated...

Achilles Over a year ago

Can you show it in an example or something ? It has to get complicated because as the initial string is going to be arbitrary, I need to find a generic form

|

Collectives™ on Stack Overflow

Replacing sub-string of a String with another String

3 Answers 3

2 Comments

12 Comments

6 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

12 Comments

6 Comments

Your Answer

Sign up or log in

Post as a guest

Related