Develop Reference

N-th indexOf in String?

I need to extract a sub-string of a URL.
URLs
/service1/api/v1.0/foo -> foo
/service1/api/v1.0/foo/{fooId} -> foo/{fooId}
/service1/api/v1.0/foo/{fooId}/boo -> foo/{fooId}/boo
And some of those URLs may have request parameters.
Code
String str = request.getRequestURI();
str = str.substring(str.indexOf("/") + 1);
str = str.substring(str.indexOf("/") + 1);
str = str.substring(str.indexOf("/") + 1);
str = str.substring(str.indexOf("/") + 1, str.indexOf("?"));
Is there a better way to extract the sub-string instead of recurrent usage of indexOf method?

There are many alternative ways:
Use Java-Stream API on splitted String with \ delimiter:
String str = "/service1/api/v1.0/foo/{fooId}/boo";
String[] split = str.split("\\/");
String url = Arrays.stream(split).skip(4).collect(Collectors.joining("/"));
System.out.println(url);
With the elimination of the parameter, the Stream would be like:
String url = Arrays.stream(split)
.skip(4)
.map(i -> i.replaceAll("\\?.+", ""))
.collect(Collectors.joining("/"));
This is also where Regex takes its place! Use the classes Pattern and Matcher.
String str = "/service1/api/v1.0/foo/{fooId}/boo";
Pattern pattern = Pattern.compile("\\/.*?\\/api\\/v\\d+\\.\\d+\\/(.+)");
Matcher matcher = pattern.matcher(str);
while (matcher.find()) {
System.out.println(matcher.group(1));
}
If you rely on the indexOf(..) usage, you might want to use the while-loop.
String str = "/service1/api/v1.0/foo/{fooId}/boo?parameter=value";
String string = str;
while(!string.startsWith("v1.0")) {
string = string.substring(string.indexOf("/") + 1);
}
System.out.println(string.substring(string.indexOf("/") + 1, string.indexOf("?")));
Other answers include a way that if the prefix is not mutable, you might want to use only one call of idndexOf(..) method (#JB Nizet):
string.substring("/service1/api/v1.0/".length(), string.indexOf("?"));
All these solutions are based on your input and fact, the pattern is known, or at least the number of the previous section delimited with \ or the version v1.0 as a checkpoint - the best solution might not appear here since there are unlimited combinations of the URL. You have to know all the possible combinations of input URL to find the best way to handle it.

Path is quite useful for that :
public static void main(String[] args) {
Path root = Paths.get("/service1/api/v1.0/foo");
Path relativize = root.relativize(Paths.get("/service1/api/v1.0/foo/{fooId}/boo"));
System.out.println(relativize);
}
Output :
{fooId}/boo

How about this:
String s = "/service1/api/v1.0/foo/{fooId}/boo";
String[] sArray = s.split("/");
StringBuilder sb = new StringBuilder();
for (int i = 4; i < sArray.length; i++) {
sb.append(sArray[i]).append("/");
}
sb.deleteCharAt(sb.length() - 1);
System.out.println(sb.toString());
Output:
foo/{fooId}/boo
If the url prefix is always /service1/api/v1.0/, you just need to do s.substring("/service1/api/v1.0/".length()).

There are a few good options here.
1) If you know "foo" will always be the 4th token, then you have the right idea already. The only issue with your way is that you have the information you need to be efficient, but you aren't using it. Instead of copying the String multiple times and looping anew from the beginning of the new String, you could just continue from where you left off, 4 times, to find the starting point of what you want.
String str = "/service1/api/v1.0/foo/{fooId}/boo";
// start at the beginning
int start = 0;
// get the 4th index of '/' in the string
for (int i = 0; i != 4; i++) {
// get the next index of '/' after the index 'start'
start = str.indexOf('/',start);
// increase the pointer to the next character after this slash
start++;
}
// get the substring
str = str.substring(start);
This will be far, far more efficient than any regex pattern.
2) Regex: (java.util.regex.*). This will work if you what you want is always preceded by "service1/api/v1.0/". There may be other directories before it, e.g. "one/two/three/service1/api/v1.0/".
// \Q \E will automatically escape any special chars in the path
// (.+) will capture the matched text at that position
// $ marks the end of the string (technically it matches just before '\n')
Pattern pattern = Pattern.compile("/service1/api/v1\\.0/(.+)$");
// get a matcher for it
Matcher matcher = pattern.matcher(str);
// if there is a match
if (matcher.find()) {
// get the captured text
str = matcher.group(1);
}
If your path can vary some, you can use regex to account for it. e.g.: service/api/v3/foo/{bar}/baz/" (note varying number formats and trailing '/') could be matched as well by changing the regex to "/service\\d*/api/v\\d+(?:\\.\\d+)?/(.+)(?:/|$)"

JAVA Get text from String

Hi I get this String from server :
id_not="autoincrement"; id_obj="-"; id_tr="-"; id_pgo="-"; typ_not=""; tresc="Nie wystawił"; datetime="-"; lon="-"; lat="-";
I need to create a new String e.x String word and send a value which I get from String tresc="Nie wystawił"

Like #Jan suggest in comment you can use regex for example :
String str = "id_not=\"autoincrement\"; id_obj=\"-\"; id_tr=\"-\"; id_pgo=\"-\"; typ_not=\"\"; tresc=\"Nie wystawił\"; datetime=\"-\"; lon=\"-\"; lat=\"-\";";
Pattern p = Pattern.compile("tresc(.*?);");
Matcher m = p.matcher(str);
if (m.find()) {
System.out.println(m.group());
}
Output
tresc="Nie wystawił";
If you want to get only the value of tresc you can use :
Pattern p = Pattern.compile("tresc=\"(.*?)\";");
Matcher m = p.matcher(str);
if (m.find()) {
System.out.println(m.group(1));
}
Output
Nie wystawił

Something along the lines of
Pattern p = Pattern.compile("tresc=\"([^\"]+)\");
Matcher m = p.matcher(stringFromServer);
if(m.find()) {
String whatYouWereLookingfor = m.group(1);
}
should to the trick. JSON parsing might be much better in the long run if you need additional values

Your question is unclear but i think you get a string from server and from that string you want the string/value for tresc. You can first search for tresc in the string you get. like:
serverString.substring(serverString.indexOf("tresc") + x , serverString.length());
Here replace x with 'how much further you want to pick characters.
Read on substring and delimiters
As values are separated by semicolon so annother solution could be:
int delimiter = serverstring.indexOf(";");
//in string thus giving you the index of where it is in the string
// Now delimiter can be -1, if lets say the string had no ";" at all in it i.e. no ";" is not found.
//check and account for it.
if (delimiter != -1)
String subString= serverstring.substring(5 , iend);
Here 5 means tresc is on number five in string, so it will five you tresc part.
You can then use it anyway you want.

Extract text from string Java

With this string "ADACADABRA". how to extract "CADA" From string "ADACADABRA" in java.
and also how to extract the id between "/" and "?" from the link below.
http://www.youtube-nocookie.com/embed/zaaU9lJ34c5?rel=0
output should be: zaaU9lJ34c5
but should use "/" and "?" in the process.

and also how to extract the id between "/" and "?" from the link below.
http://www.youtube-nocookie.com/embed/zaaU9lJ34c5?rel=0
output should be: zaaU9lJ34c5
Should be :
String url = "http://www.youtube-nocookie.com/embed/zaaU9lJ34c5?rel=0";
String str = url.substring(url.lastIndexOf("/") + 1, url.indexOf("?"));

String s = "ADACADABRA";
String s2 = s.substring(3,7);
Here 3 specifies the beginning index, and 7 specifies the stopping point.
The string returned contains all the characters from the beginning index, up to, but not including, the ending index.

I'm not entirely sure what you mean by extract, so I've provided the code to remove it from the String, I'm not certain if this is what you want.
public static void main (String args[]){
String string = "ADACADABRA";
string = string.replace("CADA", "");
System.out.println(string);
}

This is untested but something like this may help for the youtube part:
String youtubeUrl = "http://www.youtube-nocookie.com/embed/zaaU9lJ34c5?rel=0";
String[] urlParts = youtubeUrl.split("/");
String videoId = urlParts[urlParts.length - 1];
videoId = videoId.substring(0, videoId.indexOf("?"));
Extracting CADA from the string makes no sense. You will need to specify how you have determined that CADA is the string to extract.
E.g. is it because it is the middle 4 characters? Is it because you are stripping off 3 characters each side? Are you just looking for the String "CADA"? Is it characters 3,7 of the String? Is it the first 4 of the last 7 characters of a String? Is it because it contains 2 vowels and 2 consanants? I could go on..

String regex = "CADA";
Pattern p = Pattern.compile(regex, Pattern.MULTILINE);
Matcher m = p.matcher(originalText);
while (m.find()) {
String outputThis = m.group(1);
}
Use this tool http://www.regexplanet.com/advanced/java/index.html

Probably, you don't take in account the fact of java.lang.String immutability. That's why you need to assign the result of substringing to a new variable.

Substring to remove everything before first period and after second

So I have a filename that looks like this:
myFile.12345.txt
If I wanted to end up with just the "12345" how would I go about removing that from the filename if the 12345 could be anywhere between 1 and 5 numbers in length?

If you are sure that there would be 2 periods . for sure
String fileName = string.split("\\.")[1]

you can use this
String s="ghgj.7657676.jklj";
String p = s.substring(s.indexOf(".")+1,s.lastIndexOf("."));

Assuming you want to extract all the numbers, you could use a simple regex to remove all the non-digits characters:
String s = "myFile.12345.txt";
String numbers = s.replaceAll("[^\\d]","");
System.out.println(numbers); //12345
Note: It would not work with file12.12345.txt for example

static final Pattern P = Pattern.compile("^(.*?)\\.(.*?)\\.(.*?)$");
...
...
...
Matcher m = P.matcher(input);
if (m.matches()) {
//String first = m.group(1);
String middle = m.group(2);
//String last = m.group(3);
...
}

Split a string in Java if it contains digit - but include digit in result?

I'm looking to split a string using Java if it contains a digit or underscore - but I want to include the digit in the result - is this possible?
Eg.
"Linux_version"
"Linux3.1.2.x"
I want to split strings like these to get either "version" if it contains an underscore, or the digits to the end of the string if it contains a digit - e.g. from the second string above - I want "3.1.2.x"
Any help is much appreciated!

expectedString = yourString.replaceAll("^[^_0-9]+_?","");
If you just want to remove Linux or Linux_, try this:
expectedString = yourString.replaceAll("(?i)^linux_?","")

This regex replace will do it:
input.replaceAll("^.*?((?<=_)|(?=\\d))", "");

String input = "Linux_version";
//String input = "Linux3.1.2.x";
String result = null;
Pattern p = Pattern.compile("_(.*)|(\\d.*)");
Matcher m = p.matcher();
if (m.find()){
if (m.group(1) != null){
result = m.group(1); //"version"
} else if (m.group(2) != null){
result = m.group(2); //"3.1.2.x"
}
}

Can't help you with java code but I think you can use the following regex pattern;
(_|[0-9])+[.a-zA-Z0-9]+