How to find expression, evaluate and replace in Java? - java

I have the following expressions inside a String (that comes from a text file):
{gender=male#his#her}
{new=true#newer#older}
And I would like to:
Find the occurences of that pattern {variable=value#if_true#if_false}
Temporarily store those variables in fields such as variableName, variableValue, ifTrue, ifFalse as Strings.
Evaluate an expression based on variableName and variableValue according to local variables (like String gender = "male" and String new = "true").
And finally replace the pattern with ifTrue or ifFalse according to (3).
Should I use String.replaceAll() in some way, or how do I look for this expression and save the strings that are inside? Thanks for your help
UPDATE
It would be something like PHP's preg_match_all.
UPDATE 2
I solved this by using Pattern and Matcher as I post as an answer below.

If the strings always take this format, then string.split('#') is probably the way to go. This will return an array of strings in the '#' separator (e.g. "{gender=male#his#her}".split('#') = {"{gender=male", "his", "her}"}; use substring to remove the first and last character to get rid of the braces)

After strugling for a while I managed to get this working using Pattern and Matcher as follows:
// \{variable=value#if_true#if_false\}
Pattern pattern = Pattern.compile(Pattern.quote("\\{") + "([\\w\\s]+)=([\\w\\s]+)#([\\w\\s]+)#([\\w\\s]+)" + Pattern.quote("\\}"));
Matcher matcher = pattern.matcher(doc);
// if we'll make multiple replacements we should keep an offset
int offset = 0;
// perform the search
while (matcher.find()) {
// by default, replacement is the same expression
String replacement = matcher.group(0);
String field = matcher.group(1);
String value = matcher.group(2);
String ifTrue = matcher.group(3);
String ifFalse = matcher.group(4);
// verify if field is gender
if (field.equalsIgnoreCase("Gender")) {
replacement = value.equalsIgnoreCase("Female")?ifTrue:ifFalse;
}
// replace the string
doc = doc.substring(0, matcher.start() + offset) + replacement + doc.substring(matcher.end() + offset);
// adjust the offset
offset += replacement.length() - matcher.group(0).length();
}

Related

Splitting a String that has a particular structure

I have a string that goes something like this
"330 Daniel T92435"
Now I need to obtain the name "Daniel", and I could simply just type
string.substring(4,11);
But the position where a name ("Daniel") is placed could vary.
And I don't want to use the split[] method.
I was thinking if there was a way to make the substring method read data until a whitespace is found.
If input string always has the following string structure "someSymbols Name someSymbols" you can use the following regular expression to extract the name:
"[^\\s]+\\s+(\\p{Alpha}+)\\s+[^\\s]+"
\\p{Alpha} - alphabetic character;
\\s - white space;
[^\\s] - any symbol apart from the white space.
In the code below Pattern is as object representing the regular expression. In turn, Matcher is a special object that is responsible for navigation over the given string and allows discovering the parts of this string that match the pattern.
public static String findName(String source) {
Pattern pattern = Pattern.compile("[^\\s]+\\s+(\\p{Alpha}+)\\s+[^\\s]+");
Matcher matcher = pattern.matcher(source);
String result = "no match was found";
if (matcher.find()) {
result = matcher.group(1); // group 1 corresponds to the first element enclosed in parentheses (\\p{Alpha}+)
}
return result;
}
main()
public static void main(String[] args) {
System.out.println(findName("330 Daniel T92435"));
}
Output
Daniel
You can use the str.indexOf(" ") function.
int start = string.indexOf(" ")+1;
string.substring(start,start + 7);
Edit: You can use
int start = string.indexOf(" ")+1;
int end = string.indexOf(" ", start+1);
string.substring(start,end >= 0 ? end : string.length());
if you want to select the first word and don't know how long it will be.

Replace a string using a regular expression

I have a string that I would like to replace using a regular expression in java but I am not quite sure how to do this.
Let's say I have the code below:
String globalID="60DC6285-1E71-4C30-AE36-043B3F7A4CA6";
String regExpr="^([A-Z0-9]{3})[A-Z0-9]*|-([A-Z0-9]{3})[A-Z0-9]*$|-([A-Z0-9]{2})[A-Z0-9]*"
What I would like to do is apply my regExpr in globalID so the new string will be something like : 60D1E4CAE043; I did it with str.substring(0,3)+.... but I was wondering if I can do it using the regexpr in java. I tried to do it by using the replaceAll but the output was not the one I describe above.
To be more specific , I would like to change the globalID to a newglobalID using the regexpr I described above. The newglobalID will be : 60D1E4CAE043.
Thanks
This is definitively not the best code ever, but you could do something like this:
String globalID = "60DC6285-1E71-4C30-AE36-043B3F7A4CA6";
String regExpr = "^([A-Z0-9]{3})[A-Z0-9]*|-([A-Z0-9]{3})[A-Z0-9]*$|-([A-Z0-9]{2})[A-Z0-9]*";
Pattern pattern = Pattern.compile(regExpr);
Matcher matcher = pattern.matcher(globalID);
String newGlobalID = "";
while (matcher.find()) {
for (int i = 1; i <= matcher.groupCount(); i++) {
newGlobalID += matcher.group(i) != null ? matcher.group(i) : "";
}
}
System.out.println(newGlobalID);
You will need to use a Matcher to iterate over all matches in your input as your regular expression matches subsequences of the input string only. Depending on which substring is matched a different capturing group will be non-null, you could also use named capturing groups or remember where in the input you currently are, but the above code should work as example.
Your regexp must match the whole string. Your wersioe tries to match the parts alternatively which does not work.
thy this:
String regExpr="^([A-Z0-9]{3})[^-]*"+
"-([A-Z0-9]{2})[^-]*"+
"-([A-Z0-9]{3})[^-]*"+
"-([A-Z0-9]{2})[^-]*"+
"-([A-Z0-9]{2}).*"
The total code should be like that below,
String globalID = "60DC6285-1E71-4C30-AE36-043B3F7A4CA6";
String regExpr = "^(\\w{3}).*?-"
+ "(\\w{2}).*?-"
+ "(\\w{2}).*?-"
+ "(\\w{2}).*?-"
+ "(\\w{3}).*";
System.out.println(globalID.replaceAll(regExpr, "$1$2$3$4$5"));
The output of println function is
60D1E4CAE043

Parse out specific characters from java string

I have been trying to drop specific values from a String holding JDBC query results and column metadata. The format of the output is:
[{I_Col1=someValue1, I_Col2=someVal2}, {I_Col3=someVal3}]
I am trying to get it into the following format:
I_Col1=someValue1, I_Col2=someVal2, I_Col3=someVal3
I have tried just dropping everything before the "=", but some of the "someVal" data has "=" in them. Is there any efficient way to solve this issue?
below is the code I used:
for(int i = 0; i < finalResult.size(); i+=modval) {
String resulttemp = finalResult.get(i).toString();
String [] parts = resulttemp.split(",");
//below is only for
for(int z = 0; z < columnHeaders.size(); z++) {
String replaced ="";
replaced = parts[z].replace("*=", "");
System.out.println("Replaced: " + replaced);
}
}
You don't need any splitting here!
You can use replaceAll() and the power of regular expressions to simply replace all occurrences of those unwanted characters, like in:
someString.replaceAll("[\\[\\]\\{\\}", "")
When you apply that to your strings, the resulting string should exactly look like required.
You could use a regular expression to replace the square and curly brackets like this [\[\]{}]
For example:
String s = "[{I_Col1=someValue1, I_Col2=someVal2}, {I_Col3=someVal3}]";
System.out.println(s.replaceAll("[\\[\\]{}]", ""));
That would produce the following output:
I_Col1=someValue1, I_Col2=someVal2, I_Col3=someVal3
which is what you expect in your post.
A better approach however might be to match instead of replace if you know the character set that will be in the position of 'someValue'. Then you can design a regex that will match this perticular string in such a way that no matter what seperates I_Col1=someValue1 from the rest of the String, you will be able to extract it :-)
EDIT:
With regards to the matching approach, given that the value following I_Col1= consists of characters from a-z and _ (regardless of the case) you could use this pattern: (I_Col\d=\w+),?
For example:
String s = "[{I_Col1=someValue1, I_Col2=someVal2}, {I_Col3=someVal3}]";
Matcher m = Pattern.compile("(I_Col\\d=\\w+),?").matcher(s);
while (m.find())
System.out.println(m.group(1));
This will produce:
I_Col1=someValue1
I_Col2=someVal2
I_Col3=someVal3
You could do four calls to replaceAll on the string.
String query = "[{I_Col1=someValue1, I_Col2=someVal2}, {I_Col3=someVal3}]"
String queryWithoutBracesAndBrackets = query.replaceAll("\\{", "").replaceAll("\\]", "").replaceAll("\\]", "").replaceAll("\\[", "")
Or you could use a regexp if you want the code to be more understandable.
String query = "[{I_Col1=someValue1, I_Col2=someVal2}, {I_Col3=someVal3}]"
queryWithoutBracesAndBrackets = query.replaceAll("\\[|\\]|\\{|\\}", "")

Check if there is any mark after variable value with java regex

String url = /aaa/bbbb/cake/123_asd&%?/reg ex+
String variable =cake
if(url.matches(".*"+variable"+'.$'")
I would like to know if there is any mark after variable. This gives me syntax error. Any ide what is the correct syntax?
Yet another way which will display the contents of the URL after the variable:
// Your link string
String link = "/aaa/bbbb/cake/123_asd&%?/reg ex+";
// Your delimiter
String variable = "cake";
// Variable to hold the string contents located
// after the delimiter
String textAfterVar = "";
/*
To fill the textAfterVar string variable we're
going to use the Pattern Matcher method and a small
regex expression for obtaining the string portion
found after our delimiter.
Here we establish our pattern to use and place it into
a variable conveniently named pattern.... */
Pattern pattern = Pattern.compile("(?i).*(" + variable + ")+(.*)");
/*
Breakdown of the expression string: ".*(" + variable + ")+(.*)"
(?i) Ignore letter case. Remove if you want to be case sensitive.
.* Match any character 0 or more times (except newline).
( Group 1 Start...
+variable+ The string variable which holds our delimiter string.
Will be held as Group 1.
) Group 1 End.
+ Match one or more of the previous item which in this case is
the contents of our variable.
( Group 2 Start... This group will be any text after the delimiter.
.* Match any character 0 or more times (except newline).
) Group 2 End. */
/*
We now run the pattern through the matcher method to
see if there is a match to our regex expression. */
Matcher matcher = pattern.matcher(link);
// See if the matcher method finds a match to our expression.
// If so place the contents into the textAfterVar string variable.
if (matcher.find()) { textAfterVar = matcher.group(2); }
// Display the contents of the textAfterVar string
// variable in output console (pane).
System.out.println(textAfterVar);
Hope this helps.
if your String is too long you can try to use find() instead, this way you don't have to match the whole String, but instead what you are interested in (it also makes Regex easier to read too).
Pattern p = Pattern.compile(Pattern.quote(variable) + "[^$]"); //find variable + anything but end of line
Matcher matcher = p.matcher(url);
if(matcher.find()){
System.out.println("matched");
}else{
System.out.println("not matched");
}
Example:
INPUT1:
String url="/aaa/bbbb/cake/123_asd&%?/reg ex+";
String variable="cake";
OUTPUT1:
matched
INPUT2:
String url="/aaa/bbbb/cake/123_asd&%?/reg ex+.";
String variable="ex+.";
OUTPUT2:
not matched

Parsing text using Regex

So I am trying to parse a String that contains two key components. One tells me the timing options, and the other is position.
Here is what the text looks like
KB_H9Oct4GFP_20130305_p00{iiii}t00000{ttt}z001c02.tif
The {iiii} is the position and the {ttt} is the timing options.
I need to separate the {ttt} and {iiii} out so I can get a full file name: example, position 1 and time slice 1 = KB_H9Oct4GFP_20130305_p0000001t000000001z001c02.tif
So far here is how I am parsing them:
int startTimeSlice = 1;
int startTile = 1;
String regexTime = "([^{]*)\\{([t]+)\\}(.*)";
Pattern patternTime = Pattern.compile(regexTime);
Matcher matcherTime = patternTime.matcher(filePattern);
if (!matcherTime.find() || matcherTime.groupCount() != 3)
{
throw new IllegalArgumentException("Incorect filePattern: " + filePattern);
}
String timePrefix = matcherTime.group(1);
int tCount = matcherTime.group(2).length();
String timeSuffix = matcherTime.group(3);
String timeMatcher = timePrefix + "%0" + tCount + "d" + timeSuffix;
String timeFileName = String.format(timeMatcher, startTimeSlice);
String regex = "([^{]*)\\{([i]+)\\}(.*)";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(timeFileName);
if (!matcher.find() || matcher.groupCount() != 3)
{
throw new IllegalArgumentException("Incorect filePattern: " + filePattern);
}
String prefix = matcher.group(1);
int iCount = matcher.group(2).length();
String suffix = matcher.group(3);
String nameMatcher = prefix + "%0" + iCount + "d" + suffix;
String fileName = String.format(nameMatcher, startTile);
Unfortunately my code is not working and it fails when checking if the second matcher finds anything in timeFileName.
After the first regex check it gets the following as the timeFileName: 000000001z001c02.tif, so it is cutting off the beginning potions including the {iiii}
Unfortunately I cannot assuming which group goes first ({iiii} or {ttt}), so I am trying to devise a solution that just handles {ttt} first and then processes {iiii}.
Also, here is another example of valid text that I am also trying to parse: F_{iii}_{ttt}.tif
Steps to follow:
Find string {ttt...} in file name
Form a number format based on no of "t" in string
Find string {iiii...} in file name
Form a number format based on no of "i" in string
Use String.replace() method to replace time and possition
Here is the code:
String filePattern = "KB_H9Oct4GFP_20130305_p00{iiii}t00000{ttt}z001c02.tif";
int startTimeSlice = 1;
int startTile = 1;
Pattern patternTime = Pattern.compile("(\\{[t]*\\})");
Matcher matcherTime = patternTime.matcher(filePattern);
if (matcherTime.find()) {
String timePattern = matcherTime.group(0);// {ttt}
NumberFormat timingFormat = new DecimalFormat(timePattern.replaceAll("t", "0")
.substring(1, timePattern.length() - 1));// 000
Pattern patternPosition = Pattern.compile("(\\{[i]*\\})");
Matcher matcherPosition = patternPosition.matcher(filePattern);
if (matcherPosition.find()) {
String positionPattern = matcherPosition.group(0);// {iiii}
NumberFormat positionFormat = new DecimalFormat(positionPattern
.replaceAll("i", "0").substring(1, positionPattern.length() - 1));// 0000
System.out.println(filePattern.replace(timePattern,
timingFormat.format(startTimeSlice)).replace(positionPattern,
positionFormat.format(startTile)));
}
}
Okay, so after a bit of testing I found a way to handle the case:
For parsing the {ttt} I can use the regex: (.*)\\{t([t]+)\\}(.*)
Now this means I have to increment tCount by one to account for the t I grab from \\{t
Same goes for {iii}: (.*)\\{i([i]+)\\}(.*)
Your first pattern looks like this:
String regexTime = "([^{]*)\\{([t]+)\\}(.*)";
This finds a string consisting of a sequence of zero or more non-{ characters, followed by {t...t}, followed by other characters.
When your input is
KB_H9Oct4GFP_20130305_p00{iiii}t00000{ttt}z001c02.tif
the first substring that matches is
iiii}t00000{ttt}z001c02.tif
The { before the i's can't match, because you told it only to match non-{ characters. The result is that when you re-form the string to do the second match, it will start with iiii} and therefore won't match {iiii} like you're trying to do.
When you're looking for {ttt...}, I don't see any reason to exclude { or any other character from the first part of the string. So changing the regex to
"^(.*)\\{(t+\\}(.*)$"
may be a simple way to fix this. Note that if you want to make sure you include the entire beginning of the string and the entire end of the string in your groups, you should include ^ and $ to match the beginning and end of the string, respectively; otherwise the matcher engine may decide not to include everything. In this case, it won't, but it's a good habit to get into anyway, because that makes things explicit and doesn't require anyone to know the difference between "greedy" and "reluctant" matching. Or use matches() instead of find(), since matches() automatically tries to match the entire string.
Perhaps an easier way to do this (as confirmed by http://regex101.com/r/vG7kY7) is
(\{i+\}).*(\{t+\})
You don't need the [] around a single character you are matching. Keep it simple. i+ means "one or more i's", and as long as these are in the order given, this expression will work (with the first match being {iiii} and the second {ttttt}).
You may need to escape the backslash when writing it in a string...

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