Java String.replaceFirst() that takes a "starting from" argument - java

I need to replace a word in a string looking like "duh duh something else duh". I only need to replace the second "duh", but the first and the last ones need to stay untouched, so replace() and replaceFirst() don't work. Is there a method like replaceFirst(String regex, String replacement, int offset) that would replace the first occurrence of replacement starting from offset, or maybe you'd recommend some other way of solving this?
Thanks!

What about something like this:
String replaceFirstFrom(String str, int from, String regex, String replacement)
{
String prefix = str.substring(0, from);
String rest = str.substring(from);
rest = rest.replaceFirst(regex, replacement);
return prefix+rest;
}
// or
s.substring(0,start) + s.substring(start).replaceFirst(search, replace);
just 1 line of code ... not a whole method.

Will something like this work?
System.out.println(
"1 duh 2 duh duh 3 duh"
.replaceFirst("(duh.*?)duh", "$1bleh")
); // prints "1 duh 2 bleh duh 3 duh"
If you just want to replace the second occurrence of a pattern in a string, you really don't need this "starting from" index calculation.
As a bonus, if you want to replace every other duh (i.e. second, fourth, sixth, etc), then just invoke replaceAll instead of replaceFirst.

An alternative using Matcher:
String input = "duh duh something else duh";
Pattern p = Pattern.compile("duh");
Matcher m = p.matcher(input);
int startIndex = 4;
String output;
if (m.find(startIndex)) {
StringBuffer sb = new StringBuffer();
m.appendReplacement(sb, "dog");
m.appendTail(sb);
output = sb.toString();
} else {
output = input;
}

Related

How to put new string between commas in original string

I have this original string and I want to insert new string between two dots of original string. I did it this way, but having errors.
String originalString ="asdASfasdlpe.hereNeedToPutNewString.asdasfdfepw";
String stringForReplace = "NewString";
String new = originalString.replace(originalString.substring(originalString.indexOf(".") + 1), stringForReplace);
it gives me: "asdASfasdlpe.NewString"
Result should be: "asdASfasdlpe.NewString.asdasfdfepw"
I would do it like so.
from the question it looks like you want to replace the first occurrence so use replaceFirst
(?<=\\.) - look behind assertion - so start with following character
(?=\\.) - look ahead assertion - so end prior to that
.*? - reluctant quantifier to limit to just characters between two periods. Use * in case you have two adjacent periods since the string could be empty.
String s = "first.oldstring.third.fourth.fifth";
String n = "second";
s = s.replaceFirst("(?<=\\.).*?(?=\\.)",n);
System.out.println(s);
prints
first.second.third.fourth.fifth
String originalString ="asdASfasdlpe.hereNeedToPutNewString.asdasfdfepw";
String stringForReplace = "NewString";
String a[]=originalString.split("[.]");
String newString="";
if(a.length==3) {
newString=originalString.replace(a[1], stringForReplace);
}
System.out.println(newString);
Or with ternary operator:
newString=(a.length== 3 ? originalString.replace(a[1], stringForReplace):null);
System.out.println(newString);
One shorter solution is to use regex with a lookahead and lookbehind
String replaced = originalString.replaceAll("(?<=\\.).+(?=\\.)", stringForReplace);
The problem with your code is due to using this particular piece of code:
originalString.substring(originalString.indexOf(".") + 1)
The reason is that indexof() function will only give the index on which "." was found on, and substring will only know where to start taking the substring from, but it wouldn't know where to end it.
Try this:
String originalString ="asdASfasdlpe.hereNeedToPutNewString.asdasfdfepw";
String stringForReplace = "NewString";
String newString = originalString.replace(originalString.split("[.]", 3)[1], stringForReplace);
System.out.println(newString);
The split function in this piece of code will break the whole string by "."
and you will have the string you want to replace available to you.
originalString.split("[.]", 3)[1]
You could try the following:
public static void main(String[] args) {
String originalString ="asdASfasdlpe.hereNeedToPutNewString.asdasfdfepw";
String stringForReplace = "NewString";
String newStr = originalString.replaceAll("(?<=\\.).*(?=\\.)", stringForReplace);
//using lookahead and lookbehind regex
String newStr2 = originalString.replaceAll("\\..*\\.", "."+stringForReplace+".");
System.out.println(newStr);
System.out.println(newStr2);
}
One option uses lookahead and lookbehinds, you could opt to not use that if it is not supported.
Output:
asdASfasdlpe.NewString.asdasfdfepw
asdASfasdlpe.NewString.asdasfdfepw
Here You go:
String new = originalString.replace(originalString.substring(originalString.indexOf(".") + 1), stringForReplace)+originalString.substring(originalString.indexOf(".",originalString.indexOf(".")+1),originalString.length());
What I have done is adding the resultant string to the new String.indexOf function takes another argument too, which is the position the search will start

How do I replace a string while maintaining the case?

I want to replace a string by removing the s in the end
Example
Sticks -> Stick
STiCKs -> STiCK
StICks -> StICK
sticks -> stick
while using the
string.replace("sticks", "stick");
doesn't maintain case as it is case sensitive, so I'm seeking for a better option.
You could use a very simple regex for this mission.
(?i) guarantees that your regex will be treated case insensitive
Demo : (?i)(stick)s
Ideone Java Demo
string.replaceAll("(?i)(stick)s", "$1");
One possible solution is regular expressions:
StringBuffer sb = new StringBuffer();
Matcher matcher = Pattern.compile("(stick)s", Pattern.CASE_INSENSITIVE) .matcher(inputString);
while(matcher.find()) {
matcher.appendReplacement(sb, matcher.group(1));
}
matcher.appendTail(sb);
String outputString = sb.toString();
Edit: this is more or less what does String::replaceAll, but replaceAll doesn't give a case insensitive option.
If you just need to remove the 's' at the end of the String you can simply use substring method like this:
String myString = "sTiCks";
myString = myString.substring(0, myString.length()-1);
// Result "sTiCk"
If you need to remove a char or String from your String not knowing where this part will be, you can try something this:
String myString = "sTiCks";
// Part you want to delete
String stringToDelete = "Ck";
// Find where that part starts inside your String
int index = myString.indexOf(stringToDelete);
// If found, use substring method to take only what is before and after that part
if (index >= 0)
myString = myString.substring(0, index) + myString.substring(index + stringToDelete.length(), myString.length());
// Result "sTis"
This will delete the desired part only the first time it finds it. But if the part you want to delete appears more than once in your String you can modify the code to this:
String myString = "sTiCks";
// Part you want to delete
String stringToDelete = "s";
int index;
while ((index = myString.indexOf(stringToDelete)) >= 0)
myString = myString.substring(0, index) + myString.substring(index + stringToDelete.length(), myString.length());
// Result "TiCk"
I hope one of these solutions fits your case.
I don't really get why all the answers so far are so complex. You can just check the last character and if it's a s (or S) you use String#substring (documentation) and leave out the last character:
String text = "STiCks";
char lastCharacter = text.charAt(text.length() - 1);
if (lastCharacter == 'S' || lastCharacter == 's') {
text = text.substring(0, text.length() - 1);
}
If you want to apply that method to multiple words, for example in a sentence, tokenize the sentence first. Then apply the method to each word and rebuild the sentence.
String sentence = StiCks are nice, I like sticks"
String[] words = sentence.split(" ");
StringJoiner joiner = new StringJoiner(" ");
for (String word : words) {
joiner.add(removePluralSuffix(word));
}
String result = joiner.toString();
or the same with Streams:
String result = Arrays.stream(sentence.split(" "))
.map(this::removePluralSuffix)
.collect(Collectors.joining(" "));

Replacing regex with the same amount of "." as its length

See this for my current attempt: http://regexr.com?374vg
I have a regex that captures what I want it to capture, the thing is that the String().replaceAll("regex", ".") replaces everything with just one ., which is fine if it's at the end of the line, but otherwise it doesn't work.
How can I replace every character of the match with a dot, so I get the same amount of . symbols as its length?
Here's a one line solution:
str = str.replaceAll("(?<=COG-\\d{0,99})\\d", ".").replaceAll("COG-(?=\\.+)", "....");
Here's some test code:
String str = "foo bar COG-2134 baz";
str = str.replaceAll("(?<=COG-\\d{0,99})\\d", ".").replaceAll("COG-(?=\\.+)", "....");
System.out.println(str);
Output:
foo bar ........ baz
This is not possible using String#replaceAll. You might be able to use Pattern.compile(regexp) and iterate over the matches like so:
StringBuilder result = new StringBuilder();
Pattern pattern = Pattern.compile(regexp);
Matcher matcher = pattern.matcher(inputString);
int previous = 0;
while (matcher.find()) {
result.append(inputString.substring(previous, matcher.start()));
result.append(buildStringWithDots(matcher.end() - matcher.start()));
previous = matcher.end();
}
result.append(inputString.substring(previous, inputString.length()));
To use this you have to define buildStringWithDots(int length) to build a String containing length dots.
Consider this code:
Pattern p = Pattern.compile("COG-([0-9]+)");
Matcher mt = p.matcher("Fixed. Added ''Show annualized values' chackbox in EF Comp Report. Also fixed the problem with the missing dots for the positions and the problem, described in COG-18613");
if (mt.find()) {
char[] array = new char[mt.group().length()];
Arrays.fill(array, '.');
System.out.println( " <=> " + mt.replaceAll(new String(array)));
}
OUTPUT:
Fixed. Added ''Show annualized values' chackbox in EF Comp Report. Also fixed the problem with the missing dots for the positions and the problem, described in .........
Personally, I'd simplify your life and just do something like this (for starters). I'll let you finish.
public class Test {
public static void main(String[] args) {
String cog = "COG-19708";
for (int i = cog.indexOf("COG-"); i < cog.length(); i++) {
System.out.println(cog.substring(i,i+1));
// build new string
}
}
}
Can you put your regex in grouping so replace it with string that matches the length of matched grouping? Something like:
regex = (_what_i_want_to_match)
String().replaceAll(regex, create string that has that many '.' as length of $1)
?
note: $1 is what you matched in your search
see also: http://www.regular-expressions.info/brackets.html

Java how can remove everything between two substring in a string

I want to remove any substring(s) in a string that begins with 'galery' and ends with 'jssdk));'
For instance, consider the following string:
Galery something something.... jssdk));
I need an algorithm that removes 'something something....' and returns 'Galery jssdk));'
This is what I've done, but it does not work.
newsValues[1].replaceAll("Galery.*?jssdK));", "");
Could probably be improved, I've done it fast:
public static String replaceMatching(String input, String lowerBound, String upperBound{
Pattern p = Pattern.compile(".*?"+lowerBound+"(.*?)"+upperBound+".*?");
Matcher m = p.matcher(input);
String textToRemove = "";
while(m.find()){
textToRemove = m.group(1);
}
return input.replace(textToRemove, "");
}
UPDATE Thx for accepting the answer, but here is a smaller reviewed version:
public static String replaceMatching2(String input, String lowerBound, String upperBound){
String result = input.replaceAll("(.*?"+lowerBound + ")" + "(.*?)" + "(" + upperBound + ".*)", "$1$3");
return result;
}
The idea is pretty simple actually, split the String into 3 groups, and replace those 3 groups with the first and third, droping the second one.
You are almost there, but that will remove the entire string. If you want to remove anything between Galery and jssdK));, you will have to do something like so:
String newStr = newsValues[1].replaceAll("(Galery)(.*?)(jssdK\\)\\);)","$1$3");
This will put the strings into groups and will then use these groups to replace the entire string. Note that in regex syntax, the ) is a special character so it needs to be escaped.
String str = "GaleryABCDEFGjssdK));";
String newStr = str.replaceAll("(Galery)(.*?)(jssdK\\)\\);)","$1$3");
System.out.println(newStr);
This yields: GaleryjssdK));
I know that the solution presented by #amit is simpler, however, I thought it would be a good idea to show you a useful way in which you can use the replaceAll method.
Simplest solution will be to replace the string with just the "edges", effectively "removing" 1 everything between them.
newsValues[1].replaceAll("Galery.*?jssdK));", "GaleryjssdK));");
1: I used "" here because it is not exactly replacing - remember strings are immutable, so it is creating a new object, without the "removed" part.
newsValues[1] = newsValues[1].substring(0,6)+newsValues.substring(newsValues[1].length()-5,newsValues[1].length())
This basically concatenates the "Galery" and the "jssdk" leaving or ignoring everything else. More importantantly, you can simply assign newValues[1] = "Galeryjssdk"

how to find before and after sub-string in a string

I have a string say 123dance456 which I need to split into two strings containing the first sub-string before the sub-string dance (i.e. 123) and after the sub-string dance (i.e. 456). I need to find them and hold them in separate string variables, say String firstSubString = 123; and String secondSubString = 456;.
Is there any given String method that does just that?
You can use String.split(String regex). Just do something like this:
String s = "123dance456";
String[] split = s.split("dance");
String firstSubString = split[0];
String secondSubString = split[1];
Please note that if "dance" occurs more than once in the original string, split() will split on each occurrence -- that's why the return value is an array.
You can do this:
String str = "123dance456";
String substr = "dance";
String before = str.substring(0, str.indexOf(substr));
String after = str.substring(str.indexOf(substr) + substr.length());
Or
String str = "123dance456";
String substr = "dance";
String[] parts = str.split(substr);
String before = parts[0];
String after = parts[1];
It is noteworthy that the second answer not work if we have more than one occurrence of the substring. To that end, if we only want the first one to be recognized, it would be safer to call split with a limit:
String[] parts = str.split(substr, 2);
which ensures that the returned array has at most two elements. Also, since split will interpret its input as a regular expression we have to be wary of invalid regular expression syntax. As such, I would much rather the first solution, since it works irrespective of the composition of the original substring.
To make the first answer more efficient -- as it is my preferred answer -- then, we would need to remember the position of the substring:
final int position = str.indexOf(substr);
if (position >= 0) {
//if the substring does occur within the string, set the values accordingly
before = str.substring(0, position);
after = str.substring(position + substr.length());
} else {
//otherwise, default to the empty string (or some other value)
before = "";
after = "";
}
It always pays to pay attention to these little edge cases.
If you are using commons-lang see StringUtils.substringAfter()
Easiest is to use the split method as the other answers suggest. You can also use a Matcher and a Pattern for a more general approach:
String str = "123dance456";
String splitter = "dance";
Pattern p = Pattern.compile("(.*?)" + splitter + "(.*)");
Matcher m = p.matcher(str);
if (m.matches()) {
firstSubString = m.group(1); // may be empty
secondSubString = m.group(2); // may be empty
} else {
// splitter not found in str
}
String[] data = new String("123dance456").split("dance");
Using the Scanner is a nice alternative:
Scanner scanner = new Scanner( "123dance456" ).useDelimiter( "dance" );
if ( scanner.hasNext() )
System.out.println( scanner.next() );
if ( scanner.hasNext() )
System.out.println( scanner.next() );
It is quite convenient to process the tokens as a stream and simply ask via hasNext() if new tokens are available. Also you get nice conversions from the Scanner, even localised, like:
Scanner scanner = new Scanner( "123dance456" ).useDelimiter( "dance" );
System.out.println( scanner.nextDouble() * scanner.nextDouble() );

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