Eclipse won't read a config file

Question

I have an Eclipse web project. I have a file called deploy.properties in the root directory which doesn't seem to get read. I have a feeling that I may need to add the file to the "build path" (like a jar), but this is just a guess, when I try to do this there is no option for adding files to the build path so that makes me think I am wrong about that.

Line 89 is this one props.load(stream);

My stack trace looks like this:

java.lang.NullPointerException
at java.util.Properties$LineReader.readLine(Properties.java:365)
at java.util.Properties.load(Properties.java:293)
at sempedia.dao.Dao.getConfigFile(Dao.java:89)
at sempedia.dao.Dao.<clinit>(Dao.java:17) 89 

And the class looks like this:

public class Dao {
private static final String configFileLocation = "/deploy.properties";

private static final Properties configFile = getConfigFile(configFileLocation);

private static final String host = configFile.getProperty("mysql.host");
private static final String port = configFile.getProperty("mysql.port");
private static final String db   = configFile.getProperty("mysql.db");
private static final String user = configFile.getProperty("mysql.user");
private static final String pwd  = configFile.getProperty("mysql.pwd");

public static String getHost() { return host; }

public static String getPort() { return port; }

public static String getDb() { return db; }

public static String getUser() { return user; }

public static String getPwd() { return pwd; }


public static Connection getCon() {
    Connection con = null;
    try {
        String url = "jdbc:mysql://" + host + ":" + port + "/" + db;
        Class.forName("com.mysql.jdbc.Driver").newInstance();
        con = DriverManager.getConnection(url, user, pwd);

    } catch (SQLException e) {
        e.printStackTrace();
    } catch (InstantiationException e) {
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        e.printStackTrace();
    } catch (ClassNotFoundException e) {
        e.printStackTrace();
    }
    return con;
}

private static Properties getConfigFile(String fileName) {
    Properties props = new Properties();
    try {
        InputStream stream = Dao.class.getResourceAsStream(fileName);
        props.load(stream);
    } catch (IOException e) {
        System.err.println("Error opening configuration file");
        System.exit(1);
    }

    return props;
}
}

Answer 1

Keep in mind that when you read files in your eclipse project, the default location is in your source directory (if this is a web application, that translates to your classes directory later). So my advice is to try moving the file from the project root directory to your "src" directory and retrying.

Answer 2

Method Dao.class.getResourceAsStream(fileName) returns null as the inputstream if the target file doesn't exist in the classpath - that's why the NullPointerException.

You should either catch it (now you only catch IOException) or test input stream before calling props.load(stream) for null;

Now what root directory do you mean? System root, app source root, app working directory? System root would be a rather bad place to put your config files.

Address it with "deploy.properties" (without the slash at the beginning) and place it in the root of your classpath ("classes", "bin" - or whatever you call it).

If you place it in the default package level of your source directory - either in the source, or a directory that you have added as a source directory, it will be copied to the classpath during compile like this:

/app
  /src
  /config
    deploy.properties 

and now add config directory to the project as a source directory.