Update Property file in Java

Question

I have to update the value of a tag in property file. I had to persist the layout of the file after updation, so I am using PropertiesConfiguration API form APACHE.

I have done this and functionality is working as expected. Now there was few keys for those vales have backslash() and forward slash(/).When I am updating it gets changed. Backslash get removed and updation and forward slash(/) becomes / this. Below is the sample code which I am using

properties = new PropertiesConfiguration(("Dbconnect - Copy.properties"));
properties.setProperty("ConfigFilePath", "C:\\Amitabh\\Projects\\");
properties.save();
System.out.println("config.properties updated Successfully!!");

Just to know that how I will prevent. Thanks & Regards Amitabh Pandey

Are you saying that ConfigFilePath is "C:/Amitabh/Projects/" in the resulting file? — kutschkem
– kutschkem, Commented May 4, 2018 at 9:06
No it is the ConfigFilePath key value.Property file is Dbconnect - Copy.properties. — amitabh pandey
– amitabh pandey, Commented May 4, 2018 at 9:09
ABCH555466JKKK\BNH/U this one value of one key.When file gets update it will become. ABCH555466JKKKBNH\/U.Means it will remove the \ slash and convert / to \/(two slash one is backslash and one forward slash) — amitabh pandey
– amitabh pandey, Commented May 4, 2018 at 9:13
Well that's the expected behavior. If you have / it should be escaped so it escapes it with a backslash and become \/. Otherwise if it just writes / to the properties file next time you read it you will get different string. If you don't like that behaviour you can make your own reader-writer but what java does there is correct according to the properties files specification — Veselin Davidov
– Veselin Davidov, Commented May 4, 2018 at 9:25

Veselin Davidov · Accepted Answer · 2018-05-04 09:14:41Z

1

If you check here https://docs.oracle.com/javase/7/docs/api/java/util/Properties.html

You will see that slashes in properties files have special meaning. They are used to escape characters in properties - for example to spread properties across multiple lines. So before writing them to the properties file you should replace them with double slash (effectively becoming \\\\)

If you don't use Java standard properties readers and read/write the file by yourself you won't have such problems. For example you can open it as a text file and just add the property to the end basically overriding the other times it has been seen - as a work around. But better try with double-double (4) slashes

answered May 4, 2018 at 9:14

Veselin Davidov

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6 Comments

amitabh pandey Over a year ago

The string I have given is a random value.it is encrypted password. Now it is being changed by this. Can we avoid this in any other way??

Veselin Davidov Over a year ago

Then before saving it to the property file do replace("\\","\\\\")

Veselin Davidov Over a year ago

Ah that's proper way to do it then. Reading your previous comment

amitabh pandey Over a year ago

can we not have any method in PropertiesConfiguration class to do the same. Because if I will do replace then the properties file actual format will be lost. That's why I have used PropertiesConfiguration class.

Veselin Davidov Over a year ago

That is the actual format for properties files - with escaping.

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