Bdtjtk

My property file contains 3 properties I need to overwrite the value for thirdOne. How do I load the property file from class path in my java code and overwrite it..

my property file Location packagName->resource->folderName->.propertyFile

property File: I need to overwrite the value for "epochFromTime":

FILE_PATH=C:\Users\pda\Desktop\JsonOutput\DataExtract

epochFilename=C:\Users\pda\Desktop\JsonOutput\epochTime.txt

epochFromTime=1545329531862

Java Code:

try {

            Properties config = new Properties();

                config.load(ClassLoader.getSystemResourceAsStream(PROPERTIES_PATH));

                String epochFromTimeChanged= Long.toString(epoch_to2);

                config.setProperty("epochFromTime",epochFromTimeChanged);

            } catch (IOException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            } 

This is pretty easy. First do read a property file to Properties. Then update it and save it afterwards. Do not forget to close resources.

public static void updateProperties(File file, Consumer<Properties> consumer) throws IOException {

    Properties properties = new Properties();



    try (Reader reader = new BufferedReader(new FileReader(file))) {

        properties.load(reader);

    }



    consumer.accept(properties);



    try (BufferedWriter writer = new BufferedWriter(new FileWriter(file))) {

        properties.store(writer, "comment");

    }



}

Client code could look like this:

updateProperties(

        new File("application.properties"),

        properties -> {

            properties.setProperty("two", "two_two_two");

            properties.setProperty("three", "three_three");

        });

application.properties

before update

two=two_two

one=one_one

after update

#comment

#Fri Jan 04 18:59:12 MSK 2019

two=two_two_two

one=one_one

three=three_three

Use Properties.store() to write the changed value back to the file:

String PROPERTIES_PATH = "...";

try {

    File f = new File(PROPERTIES_PATH);

    FileInputStream in = new FileInputStream(f);

    Properties config = new Properties();

    config.load(in);



    String epochFromTimeChanged= Long.toString(epoch_to2);

    config.setProperty("epochFromTime",epochFromTimeChanged);



    // get or create the file

    File f = new File(PROPERTIES_PATH);

    OutputStream out = new FileOutputStream(f);

    config.store(out, "My properties file comment");



} catch (FileNotFoundException e1) {

    log.info("{} does not exist", PROPERTIES_PATH);

} catch (IOException e) {

    log.error("Cannot access {}", PROPERTIES_PATH, e);

}