Okay, so yesterday I was messing around with ODB (ObjectDB) and decided to try wrestling with it. Here’s how it went down.
First off, getting started: I downloaded the ObjectDB thing from their website. It was pretty straightforward, just clicked the link and boom, file downloaded. Unzipped it, and there it was.
Setting up the environment: I had to add the ODB jar file to my project’s classpath. This part always trips me up a bit. In IntelliJ, I went to Project Structure -> Modules -> Dependencies, and then added the JAR. Pain in the butt, but got it done.
Defining the Data: I wanted to store some simple data, like a “Person” object with a name and age. So, I created a class:
public class Person {
private String name;
private int age;
public Person(String name, int age) {
* = name;
* = age;
public String getName() { return name; }
public void setName(String name) { * = name; }
public int getAge() { return age; }
public void setAge(int age) { * = age; }
@Override
public String toString() {
return "Person{name='" + name + "', age=" + age + "}";
Pretty basic stuff, right? Nothing fancy.
Connecting to the Database: Now the fun part. I opened a database connection using ODB.
import *;
import *;
import *;
public class Main {
public static void main(String[] args) {
EntityManagerFactory emf = *("mydb");
EntityManager em = *();
// Do stuff with the database
I named the database “mydb”. You gotta create a `*` file in the `META-INF` directory to configure it. Here’s what mine looked like:
This tells ODB to use a local database file named “*” on port 6136.
Storing Data: Time to save some people! I created a few `Person` objects and persisted them.
*().begin();
Person p1 = new Person("Alice", 30);
Person p2 = new Person("Bob", 25);
*(p1);
*(p2);
*().commit();
Remember to start a transaction, persist the objects, and then commit the transaction. If you forget the transaction stuff, nothing gets saved. I learned that the hard way, haha.
Querying Data: Let’s find those people we just saved. I used JPQL (Java Persistence Query Language) to query the database.
* query = *("SELECT p FROM Person p", *);
List<Person> results = *();
for (Person person : results) {
*(person);
This query retrieves all `Person` objects from the database. Easy peasy.
Closing the Connection: Always remember to close the EntityManager and EntityManagerFactory when you’re done. Otherwise, you might end up with memory leaks or other weirdness.
What I learned: ODB is actually pretty simple to use for basic stuff. But the `*` file can be confusing at first. And don’t forget the transactions! Overall, it was a fun little experiment. I might use it for small projects where I don’t want to deal with a full-blown relational database.
