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How to read a configuration file using java.util.Properties?

When we have an application that used a text file to store a configuration and the configuration is typically in a "key"="value" format then we can use java.util.Properties to read that configuration file.

Here is the sample of app.config file:

app.name=Properties Sample Code
app.version=1.0

The code below show you how to read the configuration.

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.IOException;
import java.util.Properties;

public class PropertiesExample
{
    public static void main(String[] args)
    {
        Properties prop = new Properties();
        try
        {
            // the configuration file name
            String fileName = "app.config";            
            InputStream is = new FileInputStream(fileName);

            // load the properties file
            prop.load(is);

            // get the value for app.name key
            System.out.println(prop.getProperty("app.name"));
            // get the value for app.version key
            System.out.println(prop.getProperty("app.version"));

            // get the value for app.vendor key and if the
            // key is not available return Code Java as
            // the default value
            System.out.println(prop.getProperty("app.vendor", 
                "Code Java"));
        } catch (FileNotFoundException e)
        {
            e.printStackTrace();
        } catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}