SetAdapter doesn't work
<p>I have some sort of an issue and I'd really appreciate it, if
you could help me.
Problem: I want to take Data from a SQLite Database and display it in 
a Listview or a Gridview, either way.
I watched a tutorial and tried to follow the rules and the idea behind it,
with copying the source code and changing the code piece by piece for my
own purpose. Strangely, the code I'm having issues with works in the tutorial
code, and also in another class in my project, but refuses to work in the
recent file..</p>

<p>So, this is the oncreate of the working file:</p>

<pre><code>@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_member_list);

    mem_op = new Member_Operations(this);
    mem_op.open();

    List values = mem_op.getAllMembers();

    et = (EditText) findViewById(R.id.et1);
    et2 = (EditText) findViewById(R.id.et2);
    gv = (GridView) findViewById(R.id.gv);

   adapter = new ArrayAdapter&lt;&gt;(this,
            android.R.layout.simple_list_item_1, values);

    gv.setAdapter(adapter);


} // oncreate
</code></pre>

<p>and this is the related super-class:</p>

<pre><code>public class Member_Operations {

public DBHelper_Members db_helper;
private SQLiteDatabase database;
private String [] MEMBER_TABLE_COLUMNS = { db_helper.MEMBERS_COLUMN_ID,db_helper.MEMBERS_COLUMN_NAME,db_helper.MEMBERS_COLUMN_PERMISSION};

public Member_Operations(Context context)
{
    db_helper = new DBHelper_Members(context);
}

public void open() throws SQLException{
    database = db_helper.getWritableDatabase();
}

public void close() {
    db_helper.close();
}

public Member addMember(String name, String permission){

    ContentValues contentValues = new ContentValues();

    contentValues.put(db_helper.MEMBERS_COLUMN_NAME, name);
    contentValues.put(db_helper.MEMBERS_COLUMN_PERMISSION,permission);

    long MemID =  database.insert(db_helper.MEMBER_TABLE, null, contentValues);

    Cursor cursor = database.query(db_helper.MEMBER_TABLE,
            MEMBER_TABLE_COLUMNS,db_helper.MEMBERS_COLUMN_ID + " = " +
                    + MemID, null,null,null,null);

    cursor.moveToFirst();

    Member newComment = parseMember(cursor);
    cursor.close();

    return newComment;

}


public void deleteMember(Member mem){

    long id = mem.getID();
    SQLiteDatabase db = db_helper.getWritableDatabase();
    db.delete(db_helper.MEMBER_TABLE, db_helper.MEMBERS_COLUMN_ID + " = " + id,
           null);

}


public List getAllMembers(){

    List members = new ArrayList();

    Cursor cursor = database.query(db_helper.MEMBER_TABLE,
            MEMBER_TABLE_COLUMNS,null,null,null,null,null);

    cursor.moveToFirst();
    while(!cursor.isAfterLast()){
        Member member = parseMember(cursor);
        members.add(member);
        cursor.moveToNext();
    }

    cursor.close();
    return members;

}

private Member parseMember(Cursor cursor){
    Member member = new Member();
    member.setID(cursor.getInt(0));
    member.setName(cursor.getString(1));
    member.setPermission(cursor.getString(2));
    return member;
}
</code></pre>

<p>This is the one refusing to work:</p>

<pre><code>@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    kal_op = new Kalender_Operations(this);
    kal_op.open();

    List values = kal_op.getAllDays();


   ArrayAdapter&lt;Date&gt; adapter = new ArrayAdapter&lt;&gt;(this,
            android.R.layout.simple_list_item_1, values);
</code></pre>

<p>// here i tried, unlike the first one, to add the Type(Date). 
// But either way it doesn't work.</p>

<pre><code>   GridView gv = (GridView) findViewById(R.id.gv);


    ListActivity la = new ListActivity();
    la.setListAdapter(adapter);


}
</code></pre>

<p>And its super-class:</p>

<pre><code>public class Kalender_Operations {

SQLiteDatabase database;
DBHelper db_helper;
String [] DATES_TABLE_COLUMNS = { db_helper.JANUARY_COLUMN_ID,
db_helper.JANUARY_COLUMN_DAY,db_helper.JANUARY_COLUMN_EVENT};

public Kalender_Operations(Context context)
{
    db_helper = new DBHelper(context);
}

public void open() throws SQLException {
    database = db_helper.getWritableDatabase();
}

public void close() {
    db_helper.close();
}

public Date addDate (String day, String event){

    ContentValues contentValues = new ContentValues();

    contentValues.put(db_helper.JANUARY_COLUMN_DAY, day);
    contentValues.put(db_helper.JANUARY_COLUMN_EVENT, event);

    long DateID = database.insert(db_helper.JANUARY_TABLE,null,contentValues);

    Cursor cursor = database.query(db_helper.JANUARY_TABLE,
            DATES_TABLE_COLUMNS, db_helper.JANUARY_COLUMN_ID
                    + " = " + DateID,null,null,null,null);
    cursor.moveToFirst();

    Date newComment = parseDate(cursor);
    cursor.close();
    return newComment;


}

public void showDetails(int i, Context context){

    Intent intent = new Intent(context, Test_Intent.class);
    intent.putExtra("Position", i);
    intent.putExtra("Month", db_helper.JANUARY_TABLE);
    intent.putExtra("Year", db_helper.JANUARY_YEAR);
    context.startActivity(intent);
}

public List getAllDays(){

    List Dates = new ArrayList();

        Cursor cursor = database.query(db_helper.JANUARY_TABLE,
                DATES_TABLE_COLUMNS, null, null, null, null, null);


        cursor.moveToFirst();

    while(!cursor.isAfterLast()){
        Date date = parseDate(cursor);
        Dates.add(date);
        cursor.moveToNext();
    }
    cursor.close();



    return Dates;

}
     public Date parseDate(Cursor cursor){
    Date date = new Date();
        date.setID(cursor.getInt(0));
        date.setDay(cursor.getString(1));
        date.setEvent(cursor.getString(2));


    return date;

}
}
</code></pre>

<p>Please help me. I really want to continue learning, but I spent a lot of time now trying to figure out why one works, the other one doesn't..</p>