Updating property value in properties file without deleting other values

Question

Content of First.properties:

name=elango
country=india
phone=12345

I want change country from india to america. This is my code:

import java.io.*;
public class UpdateProperty 
{
    public static void main(String args[]) throws Exception 
    {   
        FileOutputStream out = new FileOutputStream("First.properties");
        FileInputStream in = new FileInputStream("First.properties");
        Properties props = new Properties();
        props.load(in);
        in.close();
        props.setProperty("country", "america");
        props.store(out, null);
        out.close();
    } 
}

Output content of First.properties:

country=america

The other properties are deleted. I want update a particular property value, without deleting the other properties.

Similar: https://stackoverflow.com/questions/7461901/how-to-overwrite-one-property-in-properties-without-overwriting-the-whole-file and https://stackoverflow.com/questions/565932/a-better-class-to-update-property-files — Vadzim, Jun 30 '17 at 09:44

score 105 · Accepted Answer · edited Mar 30 '23 at 16:41

105

Open the output stream and store properties after you have closed the input stream.

try (FileInputStream in = new FileInputStream("First.properties")) {
    Properties props = new Properties();
    props.load(in);
}
        
try (FileOutputStream out = new FileOutputStream("First.properties"))
    props.setProperty("country", "america");
    props.store(out, null);
}

edited Mar 30 '23 at 16:41

Born2Smile

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answered Mar 11 '13 at 11:31

Vasyl Keretsman

2,688
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Thanks Vasyl Keretsman i change code. Is it correct? Properties props = new Properties(); props.load(in); props.setProperty("country", "america"); props.store(out, null); out.close(); in.close(); but answer is same. I didn't get the expected answer – Elangovan Mar 11 '13 at 11:48
1

Not correct. I have added the code to my answer – Vasyl Keretsman Mar 11 '13 at 11:55
Thank You Vasyl Keretsman. It is working .. – Elangovan Mar 11 '13 at 12:07
@VasylKeretsman it is removed all existing comments in the file – Paraneetharan Saravanaperumal Jul 02 '15 at 09:17
Closing streams should be done in a finally block/ try-with-resources statement. – Puce Sep 07 '15 at 16:26
Maybe you are also interested in this Property Library. It can preserve order and comments. http://stackoverflow.com/questions/565932/a-better-class-to-update-property-files – Benjamin Peter Feb 19 '16 at 09:16
Yes gr8 it solved ......... but why ????? – osama yaccoub Apr 04 '16 at 17:48
7

How did this become the accepted answer ? It removes all previously set properties. – WowBow Sep 30 '16 at 00:26
This answer should state that you have to rewrite all properties again. Check this answer http://stackoverflow.com/questions/7461901/how-to-overwrite-one-property-in-properties-without-overwriting-the-whole-file – WowBow Sep 30 '16 at 00:28
Those for which the code is not working. Please verify the sequence of lines with the code provided. Sequence of lines does matter here. – Deepak Gangore Dec 07 '17 at 12:41
It removes all the previous properties. And aslo adds the timestamp in the first line of the property file. – Jayakumari Arumugham Nov 21 '19 at 11:08

AnirbanDebnath · Answer 2 · 2021-01-06T06:12:07.587

34

You can use Apache Commons Configuration library. The best part of this is, it won't even mess up the properties file and keeps it intact (even comments).

Javadoc

PropertiesConfiguration conf = new PropertiesConfiguration("propFile.properties");
conf.setProperty("key", "value");
conf.save();

edited Jan 06 '21 at 06:12

answered Sep 04 '16 at 20:44

AnirbanDebnath

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6

This is much better answer than the accepted one – Joe Hackerberg Feb 16 '17 at 14:19
@José Mª I downloaded https://commons.apache.org/proper/commons-configuration/index.html ApacheCommons Configurator 2.1.1 and it seems that `save()` method and some others doesn't exists . Is there any alternative ? – GOXR3PLUS May 12 '17 at 07:47
@GOXR3PLUS Please check this website: https://commons.apache.org/proper/commons-configuration/userguide_v1.10/howto_properties.html There is a "Saving" section where its explained. – Joe Hackerberg May 12 '17 at 09:08
@José Mª Thanks for the link . It seems to be only for the version 1.10 , not for the version 2.1.1 which is the latest :) . I am searching inside https://commons.apache.org/proper/commons-configuration/userguide/user_guide.html to find something similar . – GOXR3PLUS May 12 '17 at 09:39
1

@GOXR3PLUS Sorry I can't test it right now, but I thought it should work because there is a annotation at the header of the website where you can see: "Last Published: 08 February 2017|Version: 2.1.1" It's quite confusing, but you can still use older versions. Unfortunately, I cannot help you any more with this :( – Joe Hackerberg May 12 '17 at 10:42
1

@JoséMª I had used the 1.1 version. Also, the 2.1 version has the `save()` method in it. https://commons.apache.org/proper/commons-configuration/apidocs/org/apache/commons/configuration2/PropertiesConfiguration.html – AnirbanDebnath May 22 '17 at 07:55
@AnirbanDebnath Thank you for the info, but how can that link demonstrate it? There are only 1 match with "`save()`" in the whole page and doesn't correspond to the method description. Where is `save()` hidden? – Joe Hackerberg May 22 '17 at 08:10
Okay you are using the apache-commons thats causing the issue. Use the commons-configuration one. Use this: https://mvnrepository.com/artifact/commons-configuration/commons-configuration/1.9 – AnirbanDebnath May 22 '17 at 09:23
I am using commons configuration2 but getting an error when using above code `PropertiesConfiguration() in PropertiesConfiguration can not be applied to (java.lang.String) – J. Doem Aug 20 '17 at 00:10
1

Hi @J.Doem: You can use the Older `1.10 version` which has a String args constructor to pass the file name directly. Else, for V2, you can use the `PropertyConfiguration` class's `loadIncludeFile(String fileName)` method to pass the File name. – AnirbanDebnath Aug 20 '17 at 08:22
1

This solution solved my 2 issues. 1. Saving the file without losing other data and also 2. Keys positions are not swapped (By using other solutions i.e., with FileInput & Output streams, positions of keys are getting swapped to random positions and also comments are getting removed). – Lakshmipathi G Mar 22 '22 at 13:10

score 10 · Answer 3 · answered Mar 11 '13 at 11:39

10

Properties prop = new Properties();
prop.load(...); // FileInputStream 
prop.setProperty("key", "value");
prop.store(...); // FileOutputStream

answered Mar 11 '13 at 11:39

Joe2013

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Updating property value in properties file without deleting other values

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