CODEWITHSUNDEEP
java
Tejashwini
Tejashwini

Reputation: 95

Property updates not getting saved in java properties file

I'm trying to change some values in my config.properties file.There is change in values when I set them but it doesn't get saved. here is my code

public class Config {
String filename = "config.properties";

public void displayConfig() throws IOException {

    Properties prop = new Properties();
    InputStream input = null;

    input = getClass().getClassLoader().getResourceAsStream(filename);
    if (input == null) {
        System.out.println("unable to find " + filename);
        return;
    }
    prop.load(input);
    System.out.println();
    System.out.println(prop);
    Enumeration<?> e = prop.propertyNames();
    while (e.hasMoreElements()) {
        String key = (String) e.nextElement();
        String value = prop.getProperty(key);
        System.out.println(key + " : " + value);
    }
    return;
}

public void setConfig() throws Exception {
    File filename = new File("config.properties");
    Properties prop = new Properties();
    FileInputStream in = new FileInputStream(filename);
    prop.load(in);
    in.close();

    FileOutputStream out = new FileOutputStream("config.properties");
    prop.setProperty("db", "csv");
    prop.setProperty("user", "tej");
    prop.setProperty("password", "54321");
    prop.store(out, null);
    out.close();

    System.out.println();
    System.out.println(prop);
}

}

and the output when I call displayConfig,setConfig,displayConfig is like

{user=localhost, db=dtcc, password=12345}
db : dtcc
user : localhost
password : 12345

{user=tej, db=csv, password=54321, key=value}

{user=localhost, db=dtcc, password=12345}
db : dtcc
user : localhost
password : 12345

Upvotes: 1

Views: 1740

Answers (1)

JB Nizet
JB Nizet

Reputation: 691705

Well, that's quite expected, since displayConfig() doesn't load its properties from the same location as setConfig().

displayConfig() loads them from the resource config.properties at the root of the classpath, and setConfig loads and saves them in a file in the current directory.

BTW; even if the current directory happens to be in the classpath, I think getResourceAsStream() caches the stream content the first time it's called.

Choose your poison: either you want readable and writable files, and you should use file IO, or you want read-only resources loaded from the classpath, and you should use getResource[AsStream]. Don't mix both.

Upvotes: 3

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