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Java - Escaped backslashes being taken literally when writing to file

I want to store a URL in a properties file. This is the URL:
jdbc\:sqlserver\://dummydata\\SHARED
When programming this in Java, I obviously need to escape the backslashes. So my code ends up looking like this
properties.setProperty("db", "jdbc\\:sqlserver\\://dummydata\\\\SHARED");
The issue with this is that the properties file is saving the String URL and including the backslashes used for escaping, which is an incorrect URL. I was hoping that Java would interpret the backslashes used for escaping so that only the correct URL is saved. Is there a way to achieve this?

You're correct that a property value with : needs to escape the colons in a .properties text file, but you're not writing that text file directly.
You are giving the value to a Properties object using setProperty(), and presumably writing that to a text file using store(), and the store() method will escape the values as needed for you.
You should give the value you want to Properties, and forget about the encoding rules of the text file. Properties will handle all needed encoding. Since the value you want to give is jdbc:sqlserver://dummydata\SHARED, you write a string literal "jdbc:sqlserver://dummydata\\SHARED"
Example
String db = "jdbc:sqlserver://dummydata\\SHARED";
System.out.println(db); // To see actual string value
Properties properties = new Properties();
properties.setProperty("db", db);
try (FileWriter out = new FileWriter("test.properties")) {
properties.store(out, null);
}
Output
jdbc:sqlserver://dummydata\SHARED
Content of test.properties
#Tue Jun 11 11:54:24 EDT 2019
db=jdbc\:sqlserver\://dummydata\\SHARED
As you can see, the store() method has escaped the : and \ for you.
If you save the properties as an XML file instead, there's no need to escape anything, and Properties won't.
Example
try (FileOutputStream out = new FileOutputStream("test.xml")) {
properties.storeToXML(out, null);
}
Content of test.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<entry key="db">jdbc:sqlserver://dummydata\SHARED</entry>
</properties>

Properties.store() escapes backslashes, there is no way around it. I guess my first question is why is this an issue? Are you reading the file in any other way than using Properties.load(). If not they you don't need to worry about it as the load function will remove the escape characters.
properties.load(file);
System.out.println(properties.get("db"));
// output: jdbc\:sqlserver\://dummydata\\SHARED
As an aside are you sure you the URL is correct? Shouldn't you be storing it as properties.setProperty("jdbc:sqlserver://dummydata\SHARED")?

In the documentation for load, it says the following:
The method does not treat a backslash character, \, before a non-valid escape character as an error; the backslash is silently dropped. For example, in a Java string the sequence "\z" would cause a compile time error. In contrast, this method silently drops the backslash. Therefore, this method treats the two character sequence "\b" as equivalent to the single character 'b'.
This means that two backslashes will be treated as a single one because it's not a valid escape sequence. Loading this string should work just fine:
C:\\path\\to\\file

Single Backslash Changing to Doublebackslash in Property file

Hi this post is related to my old post. But in this I have achieved much.
I am using FileBasedConfigurationBuilder class of Apache common configuration API for updating property file in java. Below is my code:
FileBasedConfigurationBuilder<PropertiesConfiguration> builder = new FileBasedConfigurationBuilder<PropertiesConfiguration>(
PropertiesConfiguration.class)
.configure(new Parameters().properties().setFileName("test.properties")
.setThrowExceptionOnMissing(true));
PropertiesConfiguration config = builder.getConfiguration();
config.setProperty("Id", "3");
builder.save();
System.out.println("config.properties updated Successfully!!");
Now one of my key have value like
C\://ABC.net\\:1010.
After modification it becomes
C\\://ABC.net\\:1010. Means it single backslash is converting to two single backslash. Previously I was using common configuration jar 1.10 it that forwardslash also getting change. Now I have used common configuration version
commons-configuration2-2.0.jar. By this version only problem in backslash.
Can any one suggested how to avoid this? I need that after modification single backslash should not convert to doublebackslash.Please note that I don't want to change the property file.
I was following below post to reach till here.
PropertiesConfiguration - Using "/" in Property value

In a properties file, the : character is escaped with a single backslash, which is what seems to be happening in your question.
See this question How do you escape colon (:) in Properties file?
which points to the Properties documentation

Regular expression and AwkFilenameFilter

We have a folder where we dump lot of files. Our program needs to read one of the specific files with the latest version. The file name would be something like "2016-03-04-12-46-48_ABC_123456_1.xml".
Insted of reading all the files and then iterating to find the exact file i have used following code with a regular expression
File folder = new File("C:\\some_folder")
folder.listFiles((FilenameFilter) new AwkFilenameFilter("(\\d){4}-(\\d){2}-(\\d){2}-(\\d){2}-(\\d){2}-(\\d){2}_ABC_" + <ID_String> +"_(\\d){1,2}"))
But for some reason the reqular expression is not working. Can someone please help with this?

It seems you are missing the file extension in the regex:
(\\d){4}-(\\d){2}-(\\d){2}-(\\d){2}-(\\d){2}-(\\d){2}_ABC_" + <ID_String> +"_(\\d){1,2}\\.xml

Try out this one.
"\d{4}-\d{2}-\d{2}-\d{2}-\d{2}-\d{2}_ABC_"+<ID string>+"_\d{1}.xml"
It works perfectly for me.

Modifying xml via regex in java

I have the following XML String:
<asd1:content></asd1:content>
The namespace prefix asd1 could be different at different places in the XML file.
I want to modify it to :
<asd1:content>*</asd1:content>
I am trying to do it via regex as follows:
myString.replaceAll("<.*:content></.*:content>","replacement text");
The problem is that I don,t want to lose the namespace prefix. What should I do?

Please note that you've 2 typos:
cotent instead of content
replaceAlll instead of replaceAll
If you still need a regex, you can use:
String resultString = subjectString.replaceAll("(?ism)<(.*?):content></(.*?)\\.content>", "<$1:content>*</$2.content>");

how to replace a backslash in some lines of a text in Ant

Using
<replaceregexp byline="true" flags="g" file="${someFIle}"
match = "[\\]"
replace = "/"/>
I can easily replace all the \ with /.
But
Suppose the text is:
Other A\B\C
Some C\D\E
Other ...
Other ...
...
How to replace the "\" with "/" in the second line which has prefix "Some", but not other lines:
Other A\B\C
Some C/D/E
...

replaceregexp does not have options to skip lines.

Your problem cannot be merely solved by a single regex. You need to do something more complex.
1) Read properties only with the specified prefix and save them to variable. This can be done with propertyregex.
2) Read all other properties and save them somewhere.
3) Replace \ with whatever you want in the properties which contain the prefix.
4) Write the modified properties with the properties without the prefix into a file replacing the original file.
5) Enjoy :-)
Try to do these steps one by one. If you still have questions let me know.