Develop Reference

Java String to parse with different parameters

Need to parse a string having format like this -
"xxx.xxx.xxx.xxx ProxyHost=prod.loacl.com ProxyUser=test ProxyPas=tes#123 ProxyPort=1809".
Need to split or parse in such a manner that I get "prod.loacl.com" "test" "tes#123" "1809" in some strings and if any of parameters is not defined like ProxyPas then it should be null.
We need to ignore the IP addr xxx.xxx.xxx.xxx it will be always concatenated.
Do we have split or use some list to get this done...which is the best possible way to extract this information and why?
Note: Input string can change except ProxyHost parameter, user may not input the ProxyPass etc.

If you assume that format of the input string will not change, you can do something like this:
string inputString = "xxx.xxx.xxx.xxx ProxyHost=prod.loacl.com ProxyUser=test ProxyPas=tes#123 ProxyPort=1809";
string[] eachPart = inputString.Split(" ");
for(int i = 1; i < eachPart.Length; i++) // Skip the IP address
{
string[] partData = eachPart[i].Split("=");
string dataName = partData[0];
string dataValue = partData[1];
// do something with dataName and dataValue
}
However, if input string can change its format you should add some additional logic to this code.

Use regex with groups for this, sample:
var myString = "xxx.xxx.xxx.xxx ProxyHost=prod.loacl.com ProxyUser=test ProxyPas=tes123 ProxyPort=1809";
var regex = new Regex(#"ProxyHost=([^\s]+) ProxyUser=([^\s]+) ProxyPas=([^\s]+) ProxyPort=(\d+)");
var match = regex.Match(myString);
while(match != null && match.Success)
{
int i = 0;
foreach(var group in match.Groups)
{
Console.WriteLine($"Group {i}: Value:'{group}'");
i++;
}
match = match.NextMatch();
}
now you can match the groups to your properties.

One of the possible approaches is to do this Regular Expression:
([^=]+?)\=((\"[^"]+?\")|([^ ]+))
on the whole string. This allows variable input like this:
variable="this has spaces but still is recognized as one"
Problem is that seems like the variable content will be in either 3rd or 4th Group of such match, according to online regex testers, depends on if it has quotes or simply one string - must have more elegant way to do this, but can't come up with any now.
You can check this document to understand more about C#'s regexp groups:
Match.Groups
You will have to deal with null inputs accordingly, when you are putting the content into your C# variable.

How to find a String of last 2 items in colon separated string

I have a string = ab:cd:ef:gh. On this input, I want to return the string ef:gh (third colon intact).
The string apple:orange:cat:dog should return cat:dog (there's always 4 items and 3 colons).
I could have a loop that counts colons and makes a string of characters after the second colon, but I was wondering if there exists some easier way to solve it.

You can use the split() method for your string.
String example = "ab:cd:ef:gh";
String[] parts = example.split(":");
System.out.println(parts[parts.length-2] + ":" + parts[parts.length-1]);

String example = "ab:cd:ef:gh";
String[] parts = example.split(":",3); // create at most 3 Array entries
System.out.println(parts[2]);

The split function might be what you're looking for here. Use the colon, like in the documentation as your delimiter. You can then obtain the last two indexes, like in an array.

Yes, there is easier way.
First, is by using method split from String class:
String txt= "ab:cd:ef:gh";
String[] arr = example.split(":");
System.out.println(arr[arr.length-2] + " " + arr[arr.length-1]);
and the second, is to use Matcher class.

Use overloaded version of lastIndexOf(), which takes the starting index as 2nd parameter:
str.substring(a.lastIndexOf(":", a.lastIndexOf(":") - 1) + 1)

Another solution would be using a Pattern to match your input, something like [^:]+:[^:]+$. Using a pattern would probably be easier to maintain as you can easily change it to handle for example other separators, without changing the rest of the method.
Using a pattern is also likely be more efficient than String.split() as the latter is also converting its parameter to a Pattern internally, but it does more than what you actually need.
This would give something like this:
String example = "ab:cd:ef:gh";
Pattern regex = Pattern.compile("[^:]+:[^:]+$");
final Matcher matcher = regex.matcher(example);
if (matcher.find()) {
// extract the matching group, which is what we are looking for
System.out.println(matcher.group()); // prints ef:gh
} else {
// handle invalid input
System.out.println("no match");
}
Note that you would typically extract regex as a reusable constant to avoid compiling the pattern every time. Using a constant would also make the pattern easier to change without looking at the actual code.

How to add prefix to each word in a given string

I want to add prefix to every word in a given string. My code is :-
StringBuilder strColsToReturns = new StringBuilder();
String strPrefix = "abc.";
strColsToReturns.append(String.format(" %sId, %sname, %stype,", strPrefix, strPrefix, strPrefix));
This is fine, for small string, but I have a very large static string like this. So, this method of adding string prefix looks like a tedious method. Is there any other sophisticated way to achieve this.

You can use replaceAll(regex, replacement). As regex we may want to select place which has
space or start of string before it
and non-space after it.
(we can use look-around mechanisms here)
So something like this should work:
String replaced = originalString.replaceAll("(?<=\\s|^)(?=\\S)", "abc.");
But if replacement can contain $ or \ characters you will need to escape them with \, or with Matcher.quoteReplacement(replacement) method.
String originalString = "foo bar baz";
String replaced = originalString.replaceAll("(?<=\\s|^)(?=\\S)", Matcher.quoteReplacement("abc."));
System.out.println(replaced);
Output: abc.foo abc.bar abc.baz

RegEx : Insert space in the string after a matched pattern

In Java I want to insert a space after a string but only if the string contains "MAVERICK". I think using replaceAll() method which uses regular expressions as a parameter will do it, but i am not really getting it.
Here is what i have
String s = "MAVERICKA";
//the last character can be from the following set [A,Z,T,SE,EX]
So, i want the function to return me the string "MAVERICK A" or "MAVERICK EX".
Ex.
MAVERICKA -> MAVERICK A
MAVERICKEX -> MAVERICK EX
Also, if the string is already in the correct format it should not insert a space. i.e
MAVERICK A -> MAVERICK A

How about something like
s = s.replaceAll("MAVERICK(A|Z|T|SE|EX)", "MAVERICK $1");

Another solution without knowing the trailing letters would be:
String spaced_out = s.replaceAll("(MAVERICK)(?!\s|$)", "$1 ");

You mean something like this:
String r = s.replaceAll("(MAVERICK)([AZT]|SE|EX)", "$1 $2");

match all characters in a string independent of their order in the sequence

I want to match certain group of characters in a String independent of their order in the String using regex fucntion. However, the only requirement is that they all must be there.
I have tried
String elD = "15672";
String t = "12";
if ((elD.matches(".*[" + t + "].*"))) {
System.out.println(elD);
}
This one checks whether any of the characters are present. But I want all of them to be there.
Also I tried
String elD = "15672";
String t = "12";
if ((elD.matches(".*(" + t + ").*"))) {
System.out.println(elD);
}
This does not work as well. I have searched quite a while but I could not find an example when all of the characters from the pattern must be present in the String independent of their order.
Thanks

You can write regex for this but it would not look nice. If you would want to check if your string contains anywhere x and y you would need to use few times look-ahead like
^(?=.*x)(?=.*y).*$
and use it like
yourStirng.matches(regex);
But this way you would need to create your own method which would generate you dynamic regex and add (?=.*X) for each character you want to check. You would also need to make sure that this character is not special in regex like ? or +.
Simpler and not less effective solution would be creating your own method which would check if your string contains all searched characters, something like
public static boolean containsUnordered(String input, String searchFor){
char[] characters = searchFor.toCharArray();
for (char c: characters)
if (!input.contains(String.valueOf(c)))
return false;
return true;
}

You can built a pattern from the search string using the replaceAll method:
String s = "12";
String pattern = s.replaceAll("(.)", "(?=[^$1]*$1)");
Note: You can't test the same character several times. (i.e. 112 gives (?=[^1]*1)(?=[^1]*1)(?=[^2]*2) that is exactly the same as (?=[^1]*1)(?=[^2]*2))
But in my opinion Pshemo method is probably more efficient.