Delete an entry from property file

Question

How to delete key and value from property file? My property file has these contents:

key1=value1 
key2=value2

I used the below code to delete the entry key2=value2. After that, now the file has these values:

key1=value1 
key2=value2
Wed Mar 06 12:36:32 IST 2013 
key1=value1

java code to remove an entry:

FileOutputStream out1 = new FileOutputStream(file, true);
prop.remove(key);
prop.store(out1,null);

What is the mistake am doing. How to clear the whole content of the file before writing it.

Check http://stackoverflow.com/questions/4225794/delete-key-and-value-from-a-property-file — Abi, Mar 06 '13 at 07:20
Possible duplicate of [Delete key and value from a property file?](http://stackoverflow.com/questions/4225794/delete-key-and-value-from-a-property-file) — Martin Schröder, May 18 '17 at 11:29

score 7 · Accepted Answer · edited May 18 '17 at 18:15

7

1) The property file contents should look as follows:

key1=value1
key2=value2

2) You are opening the file in append mode, this is wrong. It should be:

new FileOutputStream(file);

3) Close out1 explicitly, Properties.store API:

The output stream remains open after this method returns.

If you dont want to use Properties.store, you can write Properties directly

PrintWriter pw = new PrintWriter("test.properties");
for(Entry e : props.entrySet()) {
    pw.println(e);
}
pw.close();

edited May 18 '17 at 18:15

answered Mar 06 '13 at 07:19

Evgeniy Dorofeev

"prop.store(out1,null);" is this the only way to writing a property file? – Rachel Mar 06 '13 at 10:33
it is specially designed method for saving Properties, what is special about it that it automatically converts chars to \uxxxx formmat when neecessary – Evgeniy Dorofeev Mar 06 '13 at 10:58
1

in properties file, the key and value should be in this format.. "key = jdbc:dbname:dbtype:host:port/SID,uname,pass".. but while writing with store() method, its adding escape sequences.. so now the key and value "key = jdbc\:dbname\:dbtype\:host\:port/SID,uname,pass"... how to write it without escape sequences.. – Rachel Mar 06 '13 at 11:36
this behavior is according to Properties API, it will read it back OK. Anyway, I added an example how to write Properties directly. – Evgeniy Dorofeev Mar 06 '13 at 12:07
thanks a lot.. its working.. but instead this, for(Entry e : props.entrySet()) { }, it should be, for(Entry – Rachel Mar 06 '13 at 12:22

1 Answers1