Setting more than one variable in cursor not behaving as expected

Question

I have an SQLite database with a table called author. I'm trying to pull the id and name values and pass them to the MainActivity where id will be stored as a variable and name will be displayed in a ListView.

But this is how the log (and my ListView) looks:

[com.example.apple.bookshelf.Author@31e44c75,
com.example.apple.bookshelf.Author@24fe640a,
com.example.apple.bookshelf.Author@2c87d47b,
com.example.apple.bookshelf.Author@2ab52298,
com.example.apple.bookshelf.Author@393a3af1,
com.example.apple.bookshelf.Author@2326b6d6]

I can see that the problem is because I'm adding both id and name to the AuthorList array but not specifying which one to show in the ListView. But how do I do that?

Snippet from DatabaseHelper class:

public List<String> getAllAuthors() {

        List authorList = new ArrayList();
    // Select all query
    String selectQuery = "SELECT * FROM " + AUTHORS + " ORDER BY name_alphabetic";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Author author = new Author();
            author.setID(Integer.parseInt(cursor.getString(0)));
            author.setName(cursor.getString(1));
            authorList.add(author);
        } while (cursor.moveToNext());
    }

    // return author list
    return authorList;
}

Author class:

public class Author {

    int id;
    String name;
    String name_alphabetic;

    public Author() {

    }

    public Author(int id, String name, String name_alphabetic) {
        this.id = id;
        this.name = name;
        this.name_alphabetic = name_alphabetic;
    }

    // getters

    public int getID() {
        return this.id;
    }

    public String getName() {
        return this.name;
    }

    public String getNameAlphabetic() {
        return this.name_alphabetic;
    }

    // setters

    public void setID(int id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setNameAlphabetic(String name_alphabetic) {
        this.name_alphabetic = name_alphabetic;
    }
}

Snippet from MainActivity:

        // connect authorsListView variable to XML ListView
        authorsListView = (ListView) findViewById(R.id.authors_list_view);

        // create new database helper
        DatabaseHelper db = new DatabaseHelper(this);

        // create new list through getAllAuthors method (in DatabaseHelper class)
        List authorList = db.getAllAuthors();

        Log.i("authors", authorList.toString());

        // create new Array Adapter
        ArrayAdapter<String> arrayAdapter =
                new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, authorList);

        // link ListView and Array Adapter
        authorsListView.setAdapter(arrayAdapter);

EDIT:

I solved the problem using this thread from the comment below. Adding this code to my Author class to override the toString() method inherited from the Object class did the trick:

@Override
  public String toString() {
    return name;
  }

Simple list item layout does that. You should probably have coded a proper layout for your list items, so they don't rely on `toString()`. — M. Prokhorov, Oct 30 '17 at 13:40
Use generics. If you replaced `List authorList = new ArrayList()` with `List authorList = new ArrayList<>()`, then you'll have seen your problem at compile time. — PPartisan, Oct 30 '17 at 13:44
Way 1: From Author list, create a new list along with author name alone, and set into the Array Adapter. Way 2: Create a custom Adapter class by extending ArrayAdapter. — Sackurise, Oct 30 '17 at 13:57

Cheticamp · Answer 1 · 2017-10-30T14:21:51.773

You are not really using your Author class. I suggest that you do the following:

Change your List to List<Author>:

public List<Author> getAllAuthors() {

    List<Author> authorList = new ArrayList<>();
    // Select all query
    String selectQuery = "SELECT * FROM " + AUTHORS + " ORDER BY name_alphabetic";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    // looping through all rows and adding to list
    if (cursor.moveToFirst()) {
        do {
            Author author = new Author();
            author.setID(Integer.parseInt(cursor.getString(0)));
            author.setName(cursor.getString(1));
            authorList.add(author);
        } while (cursor.moveToNext());
    }

    // return author list
    return authorList;
}

Then in MainActivity.java change the line with the ArrayAdapter:

ArrayAdapter<Author> arrayAdapter =
            new ArrayAdapter<>(this, android.R.layout.simple_list_item_1, authorList);

Make sure that toString() of Author returns the string formatted the way you want.

Setting more than one variable in cursor not behaving as expected

1 Answers1