How to get started

This tutorial will walk you through an simple greenDAO example project. It is available on and consists of two subprojects (folders): DaoExample and DaoExampleGenerator. You can either clone the git repository to get the code and run it, or just view view the files directly on github.

If you checked DaoExample out from the git repository, you can run it as an Android Application. As you can see, it’s a simple app for taking notes. You can add new notes by typing in some text, and delete notes by clicking on an existing note.

Pre-generated code and creating the table

Now, let’s look at some code. In the folder src-gen, you’ll find some already generated artifacts:
1) is a Java class containing all data a note has
2) is the DAO class, your interface to work with Note objects

You can always generate Note and NoteDao again using the DaoExampleGenerator project. But let’s stick to DaoExample for a minute. Using the DaoMaster class you can aquire a convenience SQLiteOpenHelper:

new DaoMaster.DevOpenHelper(this, "notes-db", null)

As you notice, you do not have to code “CREATE TABLE” SQL scripts. greenDAO does that for you.

Inserting and deleting notes

So once we have a table for our notes, we can put in some notes in the database. This is done in the NoteActivity class. In the onCreate method we prepare a DAO object:

daoMaster = new DaoMaster(db);
daoSession = daoMaster.newSession();
noteDao = daoSession.getNoteDao();

Now have a look at the addNote method, how you insert a new note in the database:

Note note = new Note(null, noteText, comment, new Date());
Log.d("DaoExample", "Inserted new note, ID: " + note.getId());

Just create a Java object and call insert on the DAO. When the insert method returns, the database id of the just inserted note is already assigned to the object, as you can see in the log statment.

Deleting a note is also straight forward; have a look at the onListItemClick method:


If you want, you can explore other DAO methods like loadAll and update.

Data model and code generation

In order to extend the note or to create new entities, you should have a look at the DaoExampleGenerator project. It contains a single class containing the data model definition in code:

Schema schema = new Schema(1, "de.greenrobot.daoexample");

Entity note= schema.addEntity("Note");

new DaoGenerator().generateAll(schema, "../DaoExample/src-gen");

As you can see, you create a Schema object, to which you can add entities. An entitiy is a class tied to a database table. An entity contains properties, which are mapped to database columns.
Once the schema is completely defined, you can trigger the code generation. This is how the and files where created.

Next steps

Now, that you got an impression what greenDAO looks like, it’s a good idea to get your hands dirty and try it for yourself. Also, please have a look at the documentation. If you do not find what you are looking for, please use one support options.

4 Responses to How to get started

  1. Alin says:

    How do you close the DaoSession ?
    If I have 3 activities and I need to use greenDao in eatch of them, I will have to create a new instance of DaoSession every time and I never close this sessions … It’s that ok ?

    How can I do this the right way ?

    Thank you,

  2. DaoMaster says:

    My recommendation is to start with an application-scope DaoSession. For example, have a subclass of Application and register your Application class in the manifest (or use some kind of singleton).

    I started the documentation on sessions to provide some more details (more details to come soon):

    If you have more questions, feel free to ask, preferably in the greenDAO Google group:

  3. VK says:

    Hi.. not sure where to post this question… But was wondering if greenDAO support persistence of following type of class

    class A {
    ….. other fields….

    List fields;

    can this be persisted? I am working on a project that involves such a scenario and was wondering if there is support for this.

    thanks in advance.

  4. DaoMaster says:

    VK, the best place to ask questions is the Google group:

    I’m not sure if I understood your use case. In case you want to model entities in a tree-like structure: yes, that is possible. I just updated the docs. Have a look at “Modelling Tree Relations” on this page:

    If you have further questions, let us continue the discussion in the Google group.

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