Develop Reference

How to replace a given substring with "" from a given string?

I went through a couple of examples to replace a given sub-string from a given string with "" but could not achieve the result. The String is too long to post and it contains a sub-string which is as follows:-
/image/journal/article?img_id=24810&t=1475128689597
I want to replace this sub-string with "".Here the value of img_id and t can vary, so I would have to use regular expression. I tried with the following code:-
String regex="^/image/journal/article?img_id=([0-9])*&t=([0-9])*$";
content=content.replace(regex,"");
Here content is the original given string. But this code is actually not replacing anything from the content. So please help..any help would be appreciated .thanx in advance.

Use replaceAll works in nice way with regex
content=content.replaceAll("[0-9]*","");
Code
String content="/image/journal/article?img_id=24810&t=1475128689597";
content=content.replaceAll("[0-9]*","");
System.out.println(content);
Output :
/image/journal/article?img_id=&t=
Update : simple, might be little less cozy but easy one
String content="sas/image/journal/article?img_id=24810&t=1475128689597";
content=content.replaceAll("\\/image.*","");
System.out.println(content);
Output:
sas
If there is something more after t=1475128689597/?tag=343sdds and you want to retain ?tag=343sdds then use below
String content="sas/image/journal/article?img_id=24810&t=1475128689597/?tag=343sdds";
content=content.replaceAll("(\\/image.*[0-9]+[\\/])","");
System.out.println(content);
}
Output:
sas?tag=343sdds

If you're trying to replace the substring of the URL with two quotations like so:
/image/journal/article?img_id=""&t=""
Then you need to add escaped quotes \"\" inside your content assignment, edit your regex to only look for the numbers, and change it to replaceAll:
content=content.replaceAll(regex,"\"\"");

You can use Java regex Utility to replace your String with "" or (any desired String literal), based on given pattern (regex) as following:
String content = "ALPHA_/image/journal/article?img_id=24810&t=1475128689597_BRAVO";
String regex = "\\/image\\/journal\\/article\\?img_id=\\d+&t=\\d+";
Pattern pattern = Pattern.compile(regex);
Matcher matcher = pattern.matcher(content);
if (matcher.find()) {
String replacement = matcher.replaceAll("PK");
System.out.println(replacement); // Will print ALPHA_PK_BRAVO
}

conditional replaceAll java

I have html code with img src tags pointing to urls. Some have mysite.com/myimage.png as src others have mysite.com/1234/12/12/myimage.png. I want to replace these urls with a cache file path. Im looking for something like this.
String website = "mysite.com"
String text = webContent.replaceAll(website+ "\\d{4}\\/\\d{2}\\/\\d{2}", String.valueOf(cacheDir));
This code however does not work when the url does not have the extra date stamp at the end. Does anyone know how i might achieve this? Thanks!

Try this one
mysite\.com/(\d{4}/\d{2}/\d{2}/)?
here ? means zero or more occurance
Note: use escape character \. for dot match because .(dot) is already used in regex
Sample code :
String[] webContents = new String[] { "mysite.com/myimage.png",
"mysite.com/1234/12/12/myimage.png" };
for (String webContent : webContents) {
String text = webContent.replaceAll("mysite\\.com/(\\d{4}/\\d{2}/\\d{2}/)?",
String.valueOf("mysite.com/abc/"));
System.out.println(text);
}
output:
mysite.com/abc/myimage.png
mysite.com/abc/myimage.png

You are missing a forward slash between the website.com and the first 4 digits.
String text = webContent.replaceAll(Pattern.quote(website) + "/\\d{4}\\/\\d{2}\\/\\d{2}", String.valueOf(cacheDir));
I'd also recommend using a literal for your website.com value (the Pattern.quote part).
Finally you are also missing the last forward slash after the last two digits so it won't be replaced, but that may be on purpose...

Try:
String text = webContent.replaceAll("(?<="+website+")(.*)(?=\\/)",
String.valueOf(cacheDir));

Java regex for Windows file path

I'm trying to build a Java regex to search a .txt file for a Windows formatted file path, however, due to the file path containing literal backslashes, my regex is failing.
The .txt file contains the line:
C\Windows\SysWOW64\ntdll.dll
However, some of the filenames in the text file are formatted like this:
C\Windows\SysWOW64\ntdll.dll (some developer stuff here...)
So I'm unable to use String.equals
To match this line, I'm using the regex:
filename = "C\\Windows\\SysWOW64\\ntdll.dll"
read = BufferedReader.readLine();
if (Pattern.compile(Pattern.quote(filename), Pattern.CASE_INSENSITIVE).matcher(read).find()) {
I've tried escaping the literal backslashes, using the replace method, i.e:
filename.replace("\\", "\\\\");
However, this is failing to find, I'm guessing this is because I need to further escape the backslashes after the Pattern has been built, I'm thinking I might need to escape upto an additional four backslashes, i.e:
Pattern.replaceAll("\\\\", "\\\\\\\\");
However, each time I try, the pattern doesn't get matched. I'm certain it's a problem with the backslashes, but I'm not sure where to do the replacement, or if there's a better way of building the pattern.
I think the problem is further being compounded as the replaceAll method also uses a regex, with means the pattern will have it's own backslashes in there, to deal with the case insensitivity.
Any input or advice would be appreciated.
Thanks

Seems like you're attempting to to a direct comparison of String against another. For exact matches, you could do (
if (read.equalsIgnoreCase(filename)) {
of simply
if (read.startsWith(filename)) {

Try this :
While reading each line from the file, replace '\' by '\\'.
Then :
String lLine = "C\\Windows\\SysWOW64\\ntdll.dll";
Pattern lPattern = Pattern.compile("C\\\\Windows\\\\SysWOW64\\\\ntdll\\.dll");
Matcher lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}
lLine = "C\\Windows\\SysWOW64\\ntdll.dll (some developer stuff here...)";
lMatcher = lPattern.matcher(lLine);
if(lMatcher.find()) {
System.out.println(lMatcher.group());
}

The correct usage will be:
String filename = "C\\Windows\\SysWOW64\\ntdll.dll";
String file = filename.replace('\\', ' ');

Extract String from another string in Java

Here is a string:
"http://l2.yimg.com/bt/api/res/1.2/iis49xBsStLiYI6LjauR6Q--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTg2O3E9NzU7dz0xMzA-/http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"
This string is a concatenation of two URLs. I would like to extract only the second URL:
"http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"
How can I do that using Java?

Remove everything up to "http://" not found at the start:
String url2 = str.replaceAll("(?i).+(?=https?://)", "");
This will work case insensitively and match http or https protocols.

Try this. "str" is the url string
System.out.println(str.substring(str.lastIndexOf("http:")));

If you want to extract the URL, just find the last instance of http, and take the substring:
String secondUrl = firstUrl.substring(firstUrl.lastIndexOf("http"));

Try using string's .split() method, like this:
String oneURL = twoURLs.split("(?<!^)(?=http://)")[1];
This splits the string in places that are not at the end of the string, but are followed by http://. With that, you should end up with an array like this:
["http://l2.yimg.com/bt/api/res/1.2/iis49xBsStLiYI6LjauR6Q--/YXBwaWQ9eW5ld3M7Zmk9ZmlsbDtoPTg2O3E9NzU7dz0xMzA-/", "http://media.zenfs.com/fr_FR/News/LeMonde.fr/1515504_3_f73c_le-cyber-harcelement-est-une-realite-trop-lo_450282425a88c544c2ff4121a5d9dab4.jpg"]
[1] takes only the second element of that array.
Explanation and demonstration of the regex here: http://regex101.com/r/eW6mZ0

Parsing a URL in Java

I am looking for an equivalent to PHP's "parse_url" function in Java. I am not running in Tomcat. I have query strings saved in a database that I'm trying to break apart into individual parameters. I'm working inside of Pentaho, so I only have the Java SE classes to work with. I know I could write a plugin or something, but if I'm going to do all that I'll just write the script in PHP and be done with it.
TLDR: Looking for a Java standard class/function that takes a String and spits out an array of parameters.
Thanks,
Roger

You can accomplish that using java.net.URL:
URL url = new URL("http://hostname:port/path?arg=value#anchor");
String protocol = url.getProtocol(); // http
String host = url.getHost(); // hostname
String path = url.getPath(); // /path
int port = url.getPort(); // port
String query = url.getQuery(); // arg=value
String ref = url.getRef(); // anchor

Here's something quick and dirty (have not compiled it, but you should get the idea.
URL url = new URL("http://...");
String query = url.getQuery();
String paramStrings[] = query.split("\\&");
HashMultiMap<String, String> params = HashMultiMap.create(); // <== google guava class
for (int i=0;iparamStrings.length;i++) {
String parts[] = params[i].split("=");
params.put(URLDecoder.decode(parts[0], "UTF-8"), URLDecoder.decode(parts[1], "UTF-8"));
}
Set<String> paramVals = params.get("paramName");
If you don't want to use the guava class, you can accomplish the same thing with some additional code, and a HashMap>

No such thing in Java. You will need to parse the strings manually and create your own array. You could create your own parse_url using StringTokenizer, String.split, or Regular Expressions rather easily.
You could also cast those strings from the database back to URL objects and parse them that way, here are the docs.

String has a split function, but you will need to write your own regex to determine how to split the string.
See: http://docs.oracle.com/javase/7/docs/api/java/lang/String.html#split(java.lang.String)