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Masking Email address along with domain using regex

The requirement is as below:
Input: rajani#gmail.com
Output: r****i#*****.com
I tried below two regex's but I could not able to mask the gmail(domain name). Kindly help me on this.
String masked_email_Address2=email_Address.replaceAll("(?<=.{1}).(?=[^#]*?.#)", "*");
Output received as r****i#gmail.com
I searched in stack overflow on this, I got the below regex but it does not produce the correct result:
String masked_email_Address1=email_Address.replaceAll("\\b(\\w)[^#]+#\\S+(\\.[^\\s.]+)", "$1***#****$2");
Output received as: r***#****.com -- One star(*) is missed between R&#.

I started out trying to do this with a one-liner using String#replaceAll as you were doing, but then gave up, because variable length lookbehinds are not supported, and I could not come up with a pattern which did not use them.
Instead, try just using a format pattern matcher:
String email = "rajani#gmail.com";
String pattern = "([^#]+)#(.*)\\.(.*)";
Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(email);
if (m.find( )) {
StringBuilder sb = new StringBuilder("");
sb.append(m.group(1).charAt(0));
sb.append(m.group(1).substring(1).replaceAll(".", "*"));
sb.append("#");
sb.append(m.group(2).replaceAll(".", "*"));
sb.append(".").append(m.group(3));
System.out.println(sb);
}
Demo
This may look like a lot of code to do a relatively small formatting job on an email address. If you like, you may put this code into utility method, and then you can still get the masking effect with a single line of code, when you call the method.

How about:
String masked_email_Address2=email_Address.replaceAll("(.)?[^#]*([^#])#\\S+(\\.[^\\s.]+)?", "$1****$2#****$3");
This will work as long as your address is longer than 1 character long.

Try this:
int idx = email_Address.indexOf('#');
String part1 = email_Address.substring(1, idx-1).replaceAll(".", "\\*");
String part2 = email_Address.substring(idx + 1, email_Address.lastIndexOf('.')).replaceAll(".", "\\*");
String masked_email_Address1=email_Address.replaceAll("^(\\S)[^#]+(\\S)#.*(\\..*)", "$1"+ part1 + "$2#" + part2 + "$3");

Split a string based on pattern and merge it back

I need to split a string based on a pattern and again i need to merge it back on a portion of string.
for ex: Below is the actual and expected strings.
String actualstr="abc.def.ghi.jkl.mno";
String expectedstr="abc.mno";
When i use below, i can store in a Array and iterate over to get it back. Is there anyway it can be done simple and efficient than below.
String[] splited = actualstr.split("[\\.\\.\\.\\.\\.\\s]+");
Though i can acess the string based on index, is there any other way to do this easily. Please advise.

You do not understand how regexes work.
Here is your regex without the escapes: [\.\.\.\.\.\s]+
You have a character class ([]). Which means there is no reason to have more than one . in it. You also don't need to escape .s in a char class.
Here is an equivalent regex to your regex: [.\s]+. As a Java String that's: "[.\\s]+".
You can do .split("regex") on your string to get an array. It's very simple to get a solution from that point.

I would use a replaceAll in this case
String actualstr="abc.def.ghi.jkl.mno";
String str = actualstr.replaceAll("\\..*\\.", ".");
This will replace everything with the first and last . with a .
You could also use split
String[] parts = actualString.split("\\.");
string str = parts[0]+"."+parts[parts.length-1]; // first and last word

public static String merge(String string, String delimiter, int... partnumbers)
{
String[] parts = string.split(delimiter);
String result = "";
for ( int x = 0 ; x < partnumbers.length ; x ++ )
{
result += result.length() > 0 ? delimiter.replaceAll("\\\\","") : "";
result += parts[partnumbers[x]];
}
return result;
}
and then use it like:
merge("abc.def.ghi.jkl.mno", "\\.", 0, 4);

I would do it this way
Pattern pattern = Pattern.compile("(\\w*\\.).*\\.(\\w*)");
Matcher matcher = pattern.matcher("abc.def.ghi.jkl.mno");
if (matcher.matches()) {
System.out.println(matcher.group(1) + matcher.group(2));
}
If you can cache the result of
Pattern.compile("(\\w*\\.).*\\.(\\w*)")
and reuse "pattern" all over again this code will be very efficient as pattern compilation is the most expensive. java.lang.String.split() method that other answers suggest uses same Pattern.compile() internally if the pattern length is greater then 1. Meaning that it will do this expensive operation of Pattern compilation on each invocation of the method. See java.util.regex - importance of Pattern.compile()?. So it is much better to have the Pattern compiled and cached and reused.
matcher.group(1) refers to the first group of () which is "(\w*\.)"
matcher.group(2) refers to the second one which is "(\w*)"
even though we don't use it here but just to note that group(0) is the match for the whole regex.

Java String- How to get a part of package name in android?

Its basically about getting string value between two characters. SO has many questions related to this. Like:
How to get a part of a string in java?
How to get a string between two characters?
Extract string between two strings in java
and more.
But I felt it quiet confusing while dealing with multiple dots in the string and getting the value between certain two dots.
I have got the package name as :
au.com.newline.myact
I need to get the value between "com." and the next "dot(.)". In this case "newline". I tried
Pattern pattern = Pattern.compile("com.(.*).");
Matcher matcher = pattern.matcher(beforeTask);
while (matcher.find()) {
int ct = matcher.group();
I tried using substrings and IndexOf also. But couldn't get the intended answer. Because the package name in android varies by different number of dots and characters, I cannot use fixed index. Please suggest any idea.

As you probably know (based on .* part in your regex) dot . is special character in regular expressions representing any character (except line separators). So to actually make dot represent only dot you need to escape it. To do so you can place \ before it, or place it inside character class [.].
Also to get only part from parenthesis (.*) you need to select it with proper group index which in your case is 1.
So try with
String beforeTask = "au.com.newline.myact";
Pattern pattern = Pattern.compile("com[.](.*)[.]");
Matcher matcher = pattern.matcher(beforeTask);
while (matcher.find()) {
String ct = matcher.group(1);//remember that regex finds Strings, not int
System.out.println(ct);
}
Output: newline
If you want to get only one element before next . then you need to change greedy behaviour of * quantifier in .* to reluctant by adding ? after it like
Pattern pattern = Pattern.compile("com[.](.*?)[.]");
// ^
Another approach is instead of .* accepting only non-dot characters. They can be represented by negated character class: [^.]*
Pattern pattern = Pattern.compile("com[.]([^.]*)[.]");
If you don't want to use regex you can simply use indexOf method to locate positions of com. and next . after it. Then you can simply substring what you want.
String beforeTask = "au.com.newline.myact.modelact";
int start = beforeTask.indexOf("com.") + 4; // +4 since we also want to skip 'com.' part
int end = beforeTask.indexOf(".", start); //find next `.` after start index
String resutl = beforeTask.substring(start, end);
System.out.println(resutl);

You can use reflections to get the name of any class. For example:
If I have a class Runner in com.some.package and I can run
Runner.class.toString() // string is "com.some.package.Runner"
to get the full name of the class which happens to have a package name inside.
TO get something after 'com' you can use Runner.class.toString().split(".") and then iterate over the returned array with boolean flag

All you have to do is split the strings by "." and then iterate through them until you find one that equals "com". The next string in the array will be what you want.
So your code would look something like:
String[] parts = packageName.split("\\.");
int i = 0;
for(String part : parts) {
if(part.equals("com")
break;
}
++i;
}
String result = parts[i+1];

private String getStringAfterComDot(String packageName) {
String strArr[] = packageName.split("\\.");
for(int i=0; i<strArr.length; i++){
if(strArr[i].equals("com"))
return strArr[i+1];
}
return "";
}

I have done heaps of projects before dealing with websites scraping and I
just have to create my own function/utils to get the job done. Regex might
be an overkill sometimes if you just want to extract a substring from
a given string like the one you have. Below is the function I normally
use to do this kind of task.
private String GetValueFromText(String sText, String sBefore, String sAfter)
{
String sRetValue = "";
int nPos = sText.indexOf(sBefore);
if ( nPos > -1 )
{
int nLast = sText.indexOf(sAfter,nPos+sBefore.length()+1);
if ( nLast > -1)
{
sRetValue = sText.substring(nPos+sBefore.length(),nLast);
}
}
return sRetValue;
}
To use it just do the following:
String sValue = GetValueFromText("au.com.newline.myact", ".com.", ".");

regular expression to split the string in java

I want to split the string say [AO_12345678, Real Estate] into AO_12345678 and Real Estate
how can I do this in Java using regex?
main issue m facing is in avoiding "[" and "]"
please help

Does it really have to be regex?
if not:
String s = "[AO_12345678, Real Estate]";
String[] split = s.substring(1, s.length()-1).split(", ");

I'd go the pragmatic way:
String org = "[AO_12345678, Real Estate]";
String plain = null;
if(org.startsWith("[") {
if(org.endsWith("]") {
plain = org.subString(1, org.length());
} else {
plain = org.subString(1, org.length() + 1);
}
}
String[] result = org.split(",");
If the string is always surrounded with '[]' you can just substring it without checking.

One easy way, assuming the format of all your inputs is consistent, is to ignore regex altogether and just split it. Something like the following would work:
String[] parts = input.split(","); // parts is ["[AO_12345678", "Real Estate]"]
String firstWithoutBrace = parts[0].substring(1);
String secondWithoutBrace = parts[1].substring(0, parts[1].length() - 1);
String first = firstWithoutBrace.trim();
String second = secondWithoutBrace.trim();
Of course you can tailor this as you wish - you might want to check whether the braces are present before removing them, for example. Or you might want to keep any spaces before the comma as part of the first string. This should give you a basis to modify to your specific requirements however.
And in a simple case like this I'd much prefer code like the above to a regex that extracted the two strings - I consider the former much clearer!

you can also use StringTokenizer. Here is the code:
String str="[AO_12345678, Real Estate]"
StringTokenizer st=new StringTokenizer(str,"[],",false);
String s1 = st.nextToken();
String s2 = st.nextToken();
s1=AO_12345678
s1=Real Estate
Refer to javadocs for reading about StringTokenizer
http://download.oracle.com/javase/1.4.2/docs/api/java/util/StringTokenizer.html

Another option using regular expressions (RE) capturing groups:
private static void extract(String text) {
Pattern pattern = Pattern.compile("\\[(.*),\\s*(.*)\\]");
Matcher matcher = pattern.matcher(text);
if (matcher.find()) { // or .matches for matching the whole text
String id = matcher.group(1);
String name = matcher.group(2);
// do something with id and name
System.out.printf("ID: %s%nName: %s%n", id, name);
}
}
If speed/memory is a concern, the RE can be optimized to (using Possessive quantifiers instead of Greedy ones)
"\\[([^,]*+),\\s*+([^\\]]*+)\\]"

Use String.split() with multiple delimiters

I need to split a string base on delimiter - and .. Below are my desired output.
AA.BB-CC-DD.zip ->
AA
BB
CC
DD
zip
but my following code does not work.
private void getId(String pdfName){
String[]tokens = pdfName.split("-\\.");
}

I think you need to include the regex OR operator:
String[]tokens = pdfName.split("-|\\.");
What you have will match:
[DASH followed by DOT together] -.
not
[DASH or DOT any of them] - or .

Try this regex "[-.]+". The + after treats consecutive delimiter chars as one. Remove plus if you do not want this.

You can use the regex "\W".This matches any non-word character.The required line would be:
String[] tokens=pdfName.split("\\W");

The string you give split is the string form of a regular expression, so:
private void getId(String pdfName){
String[]tokens = pdfName.split("[\\-.]");
}
That means to split on any character in the [] (we have to escape - with a backslash because it's special inside []; and of course we have to escape the backslash because this is a string). (Conversely, . is normally special but isn't special inside [].)

Using Guava you could do this:
Iterable<String> tokens = Splitter.on(CharMatcher.anyOf("-.")).split(pdfName);

For two char sequence as delimeters "AND" and "OR" this should be worked. Don't forget to trim while using.
String text ="ISTANBUL AND NEW YORK AND PARIS OR TOKYO AND MOSCOW";
String[] cities = text.split("AND|OR");
Result : cities = {"ISTANBUL ", " NEW YORK ", " PARIS ", " TOKYO ", " MOSCOW"}

pdfName.split("[.-]+");
[.-] -> any one of the . or - can be used as delimiter
+ sign signifies that if the aforementioned delimiters occur consecutively we should treat it as one.

I'd use Apache Commons:
import org.apache.commons.lang3.StringUtils;
private void getId(String pdfName){
String[] tokens = StringUtils.split(pdfName, "-.");
}
It'll split on any of the specified separators, as opposed to StringUtils.splitByWholeSeparator(str, separator) which uses the complete string as a separator

String[] token=s.split("[.-]");

It's better to use something like this:
s.split("[\\s\\-\\.\\'\\?\\,\\_\\#]+");
Have added a few other characters as sample. This is the safest way to use, because the way . and ' is treated.

Try this code:
var string = 'AA.BB-CC-DD.zip';
array = string.split(/[,.]/);

You may also specified regular expression as argument in split() method ..see below example....
private void getId(String pdfName){
String[]tokens = pdfName.split("-|\\.");
}

s.trim().split("[\\W]+")
should work.

you can try this way as split accepts varargs so we can pass multiple parameters as delimeters
String[]tokens = pdfName.split("-",".");
you can pass as many parameters that you want.

If you know the sting will always be in the same format, first split the string based on . and store the string at the first index in a variable. Then split the string in the second index based on - and store indexes 0, 1 and 2. Finally, split index 2 of the previous array based on . and you should have obtained all of the relevant fields.
Refer to the following snippet:
String[] tmp = pdfName.split(".");
String val1 = tmp[0];
tmp = tmp[1].split("-");
String val2 = tmp[0];
...