Develop Reference

Regex find optional entries in Java

I'm currently working on some stuff with regex and struggel alot with regex latetly.
I wanted to build some script engine, for that I need to load some presets:
example:
create <Type> [after;before;at;between(2);<Integer>, <DateTime>, <Date>, <Time>, <String>] : Creator
edit <Type> [after;before;at;between(2);<Integer>, <DateTime>, <Date>, <Time>, <String>]
run [<File>, <Command>]
So I want to make sure I can read <Type> [after;before;at;between(2);<Integer>, <DateTime>, <Date>, <Time>, <String>] and [<File>, <Command>].
For the understanding:
NAME <IMPORTANT_PARAMETER> [TEXT_PARAMETER(AMOUNT_OF_OPTIONAL_PAREMETER);<OPTIONAL_PARAMETER(S)>].
In this example I used 'command names' as IMPORTANT_PARAMETER.
For the first rule I made this regex: \<(\w+)\>(?:\s+\[(?:(.*;))(.*)\])?(?:\s+\:\s+(\w+))? and it kinda works within my code:
Pattern p = Pattern.compile("\\<(\\w+)\\>(?:\\s+\\[(?:(.*;))(.*)\\])?(?:\\s+\\:\\s+(\\w+))?");
Matcher m = p.matcher(parameters);
if(m.matches()){
Command command2 = new Command(command);
command2.addParameter(new Parameter(m.group(1)));
String text = m.group(2);
String[] texts = null;
if(text != null){
texts = text.split(";");
command2.addTexts(Arrays.asList(texts));
}
String type = m.group(3);
String[] types = null;
if(type != null){
types = type.split(", ");
for (String string : types) {
Pattern pTypes = Pattern.compile("\\<(?:(\\w+))\\>");
Matcher mTypes = pTypes.matcher(string);
if(mTypes.matches()){
command2.addParameter(new Parameter(mTypes.group(1), true));
}
}
}
String className = m.group(4);
if(className != null){
command2.addClassName(className);
}
commandslist.add(command2);
}
I tried to use \[\<(\w+)\>(?:,\s+\<(\w+)\>)+\] but it only worked for two entries -> example run [<File>, <Command>]. It would be better having a "list" of those optional elements [<File>, <Command>]. So in the end I want to have m.group(1) = File; m.group(2) = Command; m.group(3) = blablabla; and so on.
I hope I could show you my problem good enough, hit me with questions if there is anything more to explain.
Here is a link to the regexr: REGEXR or regex101: REGEX101
Thanks for helping :)

My suggestion is to match the stuff between the words you are after:
public static void main (String[] args) {
final String STR1 = "run [<File>, <Command1>, <Command2>, <Command3>]";
final String STR2 = "run [<File>, <Command1>, <Command2>, <Command3>, <Command4>]";
System.out.println(parse(STR1));
System.out.println(parse(STR2));
}
private static List parse(String str) {
List<String> list = new ArrayList<>();
Pattern p = Pattern.compile("(?:\\G,\\s+|^run\\s+\\[(?:<\\w+>,\\s+)+?)<(\\w+)>");
Matcher m = p.matcher(str);
while (m.find()) {
list.add(m.group(1));
}
return list;
}
which results in the output:
[Command1, Command2, Command3]
[Command1, Command2, Command3, Command4]

Why is Java placing the string before the word and not after?

from the String value want to getting word before and after the <in>
String ref = "application<in>rid and test<in>efd";
int result = ref.indexOf("<in>");
int result1 = ref.lastIndexOf("<in>");
String firstWord = ref.substring(0, result);
String[] wor = ref.split("<in>");
for (int i = 0; i < wor.length; i++) {
System.out.println(wor[i]);
}
}
my Expected Output
String[] output ={application,rid,test,efd}
i tried with 2 Option first one IndexOf but if the String have more than two <in>i 'm not getting my expected output
Second One splitits also not getting with my expected Output
please suggest best option to getting the word(before and after <in>)

You could use an expression like so: \b([^ ]+?)<in>([^ ]+?)\b (example here). This should match the string prior and after the <in> tag and place them in two groups.
Thus, given this:
String ref = "application<in>rid and test<in>efd";
Pattern p = Pattern.compile("\\b([^ ]+?)<in>([^ ]+?)\\b");
Matcher m = p.matcher(ref);
while(m.find())
System.out.println("Prior: " + m.group(1) + " After: " + m.group(2));
Yields:
Prior: application After: rid
Prior: test After: efd
Alternatively using split:
String[] phrases = ref.split("\\s+");
for(String s : phrases)
if(s.contains("<in>"))
{
String[] split = s.split("<in>");
for(String t : split)
System.out.println(t);
}
Yields:
application
rid
test
efd

Regex is your friend :)
public static void main(String args[]) throws Exception {
String ref = "application<in>rid and test<in>efd";
Pattern p = Pattern.compile("\\w+(?=<in>)|(?<=<in>)\\w+");
Matcher m = p.matcher(ref);
while (m.find()) {
System.out.println(m.group());
}
}
O/P :
application
rid
test
efd

No doubt matching what you need using Pattern/Matcher API is simpler for tis problem.
However if you're looking for a short and quick String#split solution then you can consider:
String ref = "application<in>rid and test<in>efd";
String[] toks = ref.split("<in>|\\s+.*?(?=\\b\\w+<in>)");
Output:
application
rid
test
efd
RegEx Demo
This regex splits on <in> or a pattern that matches a space followed by 0 more chars followed by a word and <in>.

You can also try the below code, it is quite simple
class StringReplace1
{
public static void main(String args[])
{
String ref = "application<in>rid and test<in>efd";
System.out.println((ref.replaceAll("<in>", " ")).replaceAll(" and "," "));
}
}

java tokenizer for strings

I have a text file and want to tokenize its lines -- but only the sentences with the # character.
For example, given...
Buah... Molt bon concert!! #Postconcert #gintonic
...I want to print only #Postconcert #gintonic.
I have already tried this code with some changes...
public class MyTokenizer {
/**
* #param args
*/
public static void main(String[] args) {
tokenize("Europe3.txt","allo.txt");
}
public static void tokenize(String sFile,String sFileOut) {
String sLine="", sToken="";
MyBufferedReaderWriter f = new MyBufferedReaderWriter();
f.openRFile(sFile);
MyBufferedReaderWriter fOut = new MyBufferedReaderWriter();
fOut.openWFile(sFileOut);
while ((sLine=f.readLine()) != null) {
//StringTokenizer st = new StringTokenizer(sLine, "#");
String[] tokens = sLine.split("\\#");
for (String token : tokens)
{
fOut.writeLine(token);
//System.out.println(token);
}
/*while (st.hasMoreTokens()) {
sToken = st.nextToken();
System.out.println(sToken);
}*/
}
f.closeRFile();
}
}
Can anyone help?

You can try something like with Regex:
package com.stackoverflow.answers;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class HashExtractor {
public static void main(String[] args) {
String strInput = "Buah... Molt bon concert!! #Postconcert #gintonic";
String strPattern = "(?:\\s|\\A)[##]+([A-Za-z0-9-_]+)";
Pattern pattern = Pattern.compile(strPattern);
Matcher matcher = pattern.matcher(strInput);
while (matcher.find()) {
System.out.println(matcher.group());
}
}
}

As per the given example, when using the split() function the values would be stored something like this:
tokens[0]=Buah... Molt bon concert!!
tokens[1]=Postconcert
tokens[2]=gintonic
So you just need to skip first value and append '#' (if you need that in your other) to the other string values.
Hope this helps.

You have not specially asked for this, but I assume you try to extract all the #hashtags from your textfile.
To do this, Regex is your friend:
String text = "Buah... Molt bon concert!! #Postconcert #gintonic";
System.out.println(getHashTags(text));
public Collection<String> getHashTags(String text) {
Pattern pattern = Pattern.compile("(#\\w+)");
Matcher matcher = pattern.matcher(text);
Set<String> htags = new HashSet();
while (matcher.find()) {
htags.add(matcher.group(1));
}
return htags;
}
Compile a pattern like this #\w+, everything that starts with a # followed by one or more (+) word character (\w).
Then we have to escape the \ for java with a \\.
And finally put this expression in a group to get access to the matched text by surrounding it with braces (#\w+).
For every match, add the first matched group to the set htags, finally we get a set with all the hashtags in it.
[#gintonic, #Postconcert]

Regex after a special character in Java

I am using regex in java to get a specific output from a list of rooms at my University.
A outtake from the list looks like this:
(A55:G260) Laboratorium 260
(A55:G292) Grupperom 292
(A55:G316) Grupperom 316
(A55:G366) Grupperom 366
(HDS:FLØYEN) Fløyen (appendix)
(ODO:PC-STUE) Pulpakammeret (PC-stue)
(SALEM:KONF) Konferanserom
I want to get the value that comes between the colon and the parenthesis.
The regex I am using at the moment is:
pattern = Pattern.compile("[:]([A-Za-z0-9ÆØÅæøå-]+)");
matcher = pattern.matcher(room.text());
I've included ÆØÅ, because some of the rooms have Norwegian letters in them.
Unfortunately the regex includes the building code also (e.g. "A55") in the output... Comes out like this:
A55
A55
A55
:G260
:G292
:G316
Any ideas on how to solve this?

The problem is not your regular expression. You need to reference group(1) for the match result.
while (matcher.find()) {
System.out.println(matcher.group(1));
}
However, you may consider using a negated character class instead.
pattern = Pattern.compile(":([^)]+)");

You can try a regex like this :
public static void main(String[] args) {
String s = "(HDS:FLØYEN) Fløyen (appendix)";
// select everything after ":" upto the first ")" and replace the entire regex with the selcted data
System.out.println(s.replaceAll(".*?:(.*?)\\).*", "$1"));
String s1 = "ODO:PC-STUE) Pulpakammeret (PC-stue)";
System.out.println(s1.replaceAll(".*?:(.*?)\\).*", "$1"));
}
O/P :
FLØYEN
PC-STUE

Can try with String Opreations as follows,
String val = "(HDS:FLØYEN) Fløyen (appendix)";
if(val.contains(":")){
String valSub = val.split("\\s")[0];
System.out.println(valSub);
valSub = valSub.substring(1, valSub.length()-1);
String valA = valSub.split(":")[0];
String valB = valSub.split(":")[1];
System.out.println(valA);
System.out.println(valB);
}
Output :
(HDS:FLØYEN)
HDS
FLØYEN

import java.util.regex.Matcher;
import java.util.regex.Pattern;
class test
{
public static void main( String args[] ){
// String to be scanned to find the pattern.
String line = "(HDS:FLØYEN) Fløyen (appendix)";
String pattern = ":([^)]+)";
// Create a Pattern object
Pattern r = Pattern.compile(pattern);
// Now create matcher object.
Matcher m = r.matcher(line);
while (m.find()) {
System.out.println(m.group(1));
}
}
}

Java Pattern match

I've a long template from which I need to extract certain strings based on certain patterns. When I went through some examples I found that use of quantifiers is good in such situations.For example following is my template, from which I need to extract while and doWhile.
This is a sample document.
$while($variable)This text can be repeated many times until do while is called.$endWhile.
Some sample text follows this.
$while($variable2)This text can be repeated many times until do while is called.$endWhile.
Some sample text.
I need to extract the whole text, starting from $while($variable) till $endWhile. I then need to process the value of $variable. After that I need to insert the text between $while and $endWhile to the original text.
I've the logic of extracting the variable. But I'm not sure how to use quantifiers or pattern match here.
Can someone please provide me a sample code for this? Any help will be greatly appreciated

You can use a rather simple regex-based solution here with a Matcher:
Pattern pattern = Pattern.compile("\\$while\\((.*?)\\)(.*?)\\$endWhile", Pattern.DOTALL);
Matcher matcher = pattern.matcher(yourString);
while(matcher.find()){
String variable = matcher.group(1); // this will include the $
String value = matcher.group(2);
// now do something with variable and value
}
If you want to replace the variables in the original text, you should use the Matcher.appendReplacement() / Matcher.appendTail() solution:
Pattern pattern = Pattern.compile("\\$while\\((.*?)\\)(.*?)\\$endWhile", Pattern.DOTALL);
Matcher matcher = pattern.matcher(yourString);
StringBuffer sb = new StringBuffer();
while(matcher.find()){
String variable = matcher.group(1); // this will include the $
String value = matcher.group(2);
// now do something with variable and value
matcher.appendReplacement(sb, value);
}
matcher.appendTail(sb);
Reference:
Methods of the Pattern Class
(Sun Java Tutorial)
Methods of the Matcher Class
(Sun Java Tutorial)
Pattern JavaDoc
Matcher JavaDoc

public class PatternInString {
static String testcase1 = "what i meant here";
static String testcase2 = "here";
public static void main(String args[])throws StringIndexOutOfBoundsException{
PatternInString testInstance= new PatternInString();
boolean result = testInstance.occurs(testcase1,testcase2);
System.out.println(result);
}
//write your code here
public boolean occurs(String str1, String str2)throws StringIndexOutOfBoundsException
{ int i;
boolean result=false;
int num7=str1.indexOf(" ");
int num8=str1.lastIndexOf(" ");
String str6=str1.substring(num8+1);
String str5=str1.substring(0,num7);
if(str5.equals(str2))
{
result=true;
}
else if(str6.equals(str2))
{
result=true;
}
int num=-1;
try
{
for(i=0;i<str1.length()-1;i++)
{ num=num+1;
num=str1.indexOf(" ",num);
int num1=str1.indexOf(" ",num+1);
String str=str1.substring(num+1,num1);
if(str.equals(str2))
{
result=true;
break;
}
}
}
catch(Exception e)
{
}
return result;
}
}