playing with variables in java

EnvVarTest.java

package com.myproject;

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

public class EnvVarTest {

    public final Properties properties;

    public EnvVarTest(){
        this.properties = new Properties();
        String propertiesFileName = "config.properties";
        InputStream inputStream = getClass().getClassLoader().getResourceAsStream(propertiesFileName);
        try{
            this.properties.load(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public String getEnvVarOrProperty(String envVarName){
        String systemEnvVar = System.getenv(envVarName);
        if (systemEnvVar == null){
            systemEnvVar = properties.getProperty(envVarName);
        }
        return systemEnvVar;
    }

    public static void main(String[] args){
        String eventsSourcePath;
        String processedRegisteredEventsPath;
        String processedAppLoadedEventsPath;
        String sparkMasterConfig;

        EnvVarTest envVarTest = new EnvVarTest();


        eventsSourcePath = envVarTest.getEnvVarOrProperty("EVENTS_SOURCE_PATH");
        processedRegisteredEventsPath = envVarTest.getEnvVarOrProperty("PROCESSED_REGISTERED_EVENTS_PATH");
        processedAppLoadedEventsPath = envVarTest.getEnvVarOrProperty("PROCESSED_APPLOADED_EVENTS_PATH");
        sparkMasterConfig = envVarTest.getEnvVarOrProperty("SPARK_MASTER");
        System.out.println("EVENTS_SOURCE_PATH -> " + eventsSourcePath);
        System.out.println("PROCESSED_REGISTERED_EVENTS_PATH -> " + processedRegisteredEventsPath);
        System.out.println("PROCESSED_APPLOADED_EVENTS_PATH -> " + processedAppLoadedEventsPath);
        System.out.println("SPARK_MASTER -> " + sparkMasterConfig);
    }
}

Protip: config.properties file should be in the "resources" folder of the project!