Articles for those who are in the early stages of a programming career
One long term features of the Delphi / C++ Builder / RAD Studio and Appmethod IDE’s is the data explorer, however did you know it has had a great facelift recently to make it even easier to use and much more practical to work with?
Join me in this Skill Sprint video as I look in depth at the updates and changes to the data explorer and how its really come of age.
Last year I had the pleasure of hosting the majority of the mobile development training series “Developer Direct – Summer School“. It was great fun covering everything from Application UI design to local storage through to remote data collection.
The last year has seem some major enhancements to RAD Studio and Appmethod with new components making some of this easier and more exciting with new possibilities, so the content has been updated and re-run by David I and Jim McKeeth in both C++ and Object Pascal/Delphi programming lessons.
To watch the 6 iOS and Android native development lessons register for free at http://forms.embarcadero.com/RADSummerSchool2014
In this blog I want to take you through the steps for getting your Android device working with the standard USB device drivers, including steps to follow to check if what you have done has worked.
Jim McKeeth did a blog post a while back about installing custom specified Android devices that is worth reading if your device does not work with the standard drivers, however I would recommend trying this first.
When you plug in your Android device, you will need to ensure you have enabled developer mode and confirmed that you want to enable USB Debugging. Under “Setting”, you should be able to see
{ } Developer options
as a menu item. If you don’t, tap “About phone” menu item 5 times to start the messages about going into developer mode.
It is also worth checking at this point that “USB Debugging” is enabled under developer options. You will still need to confirm on the phone when you finally have it all setup and you plug the phone in for the first time, but this is the first steps.
On windows, you need to have the drivers installed for the phone to enable it for developer work. Once you plug the device in, check the device manager. If it shows under Other Devices with a yellow alert, then you will need to update the drivers.
You can download the drivers if you search the web for them and point to those, or you can download and install them easily with the Android SDK Manager.
To launch the Android SDK Manager, first open a command prompt and navigate to the android SDK tools folder. With Appmethod / RAD Studio they will be installed by default in the public documents. You can reach them using the cd command. e.g.
cd \Users\Public\Documents\Embarcadero\Studio\14.0\PlatformSDKs\adt-bundle-windows-x86-20131030\sdk\tools
From the SDK tools folder type in Android and hit enter and the SDK manager will open.
With the Android SDK Manager launched you can now see the packages installed / to update. Specifically we are looking for the Google USB Driver. (see image below) Once found, choose “Install xx packages” button at the bottom of the screen.
Note: If you don’t see it, then install any packages that are pending update, close and re-open. It should then connect back to the Internet and refresh the list and make the Google USB Driver visible ready to install.
Once you have the drivers on your machine, the next step is to update the driver back in the device manager.
Choose to browse the computer and go back to the PlatformSDKs folder (path above) and choose to search sub folders.
If you have not already said to “always trust” google inc. You should see immediately be asked to confirm installing the driver.
Once installed the Android Composite ADB Interface driver will be installed and you will get confirmation.
At this point, you should be able to see in the device manager the device is installed.
With the phone drivers installed, it is now time to check the ADB command line can see your device. If it can, then you are ready to use it for development.
To check that ADB can see your device, its time to head back to the command line and run the ADB application. ADB.exe lives in the ..sdk\platform-tools folder. From the command line you should be able to get there with something like…
cd \Users\Public\Documents\Embarcadero\Studio\14.0\PlatformSDKs\adt-bundle-windows-x86-20131030\sdk\platform-tools
Once your command prompt window is open at Platform Tools, run the following command to view the connected devices.
adb devices
The following screen below shows the output. Here I have my android device connected, but as yet I have not confirmed the connection on my phone as being allowed This causes the device to show as unauthorized.
If the android device shows as unauthorized then unlock the phone and choose to Allow USB debugging.
Once the device is approved, you should be able to re-run the ADB devices command and see the device id nows shows the status of “device”
At this point you are ready to use your android device for development! Refresh your Android devices in your IDE (right click on Android as a Target platform in the Project Manager and it will become visible.
Ever wanted to select specific rows from a dataset? Well InterBase has some very cool features in the SQL syntax that allows you to do just that!
Adding the ROWS command to the end of your SQL statement (as per the example below) will return a specific number of records. For examples, to fetch the first 10 records just add rows 10.
Select * from MyTable rows 10;
When you want to get the next 10 records you can use the extended syntax with the “to” command.
Select * from MyTable rows 11 to 20;
The second query can obviously be used to fetch records 1 to 10 as well and is very useful when combined with a parameterised query to allow restful paging of data sets.
Now, say you wanted to get the first record of every page of data, you can also easily do this by adding an additional optional parameter “by” for example
Select * from MyTable rows 1 to 100 by 10;
The above statement would return records 1, 11, 21, 31 etc… for the total records up to 100th record.
You can also skip records to return by a percentage of the dataset result size by simply adding “PERCENT” to the end of the above statement.
Select * from MyTable rows 1 to 100 by 7 PERCENT;
But what if you want to use ROWS to get the top 10? Well, you can easily select 10 records, but what if the 11th and 12th record have the same value as the 10th? They should be returned as well, but how?
InterBase supports this easily by adding “WITH TIES”. To use “WITH TIES” you also need to include an “ORDER BY” clause to indicate what field to measure the ties on. For example, to get the top 10 sales people by a field storing the sales_booked, you could run the following statement.
Select * from salespeople order by sales_booked desc rows 10 with ties;
This will include the top 10 and also anyone with sales_booked matching the 10th record.
Following on, the first 10% of records can be returned by using the following syntax.
Select * from salespeople rows 10 percent;
While getting 10% of records is a nice feature, combining this with the “ORDER BY” and “WITH TIES” makes a very easy way to select the top 10% of sales people (for example) rather than the top 10.
There are some very cool features in the InterBase language for defining the specific size and scope of data to return that lend itself nicely to a range of useful implementations around statistics and restful data service development.
For more fun details on the InterBase language, check out the language reference guide on http://docs.embarcadero.com/products/interbase
Its very easy to create a drop down list using the TComboBox to select a single item, but how can you easily select multiple items from a list across iOS and Android? Once easy way is to use the TListView component in EditMode. To view an example of this, add a TListView to a new form and using the FormCreate add in 20 items using a simple loop.
procedure TForm1.FormCreate(Sender: TObject);
var
I: Integer;
begin
ListView1.BeginUpdate;
try
for I := 1 to 20 do
ListView1.Items.Add.Text := I.ToString();
finally
ListView1.EndUpdate;
end;
end;
Also note the use of BeginUpdate and EndUpdate using the Try Finally block to speed up the processing. This prevents the ListView from redrawing between each item add.
Now using two buttons we can add on click events to see how to toggle the EditMode..
procedure TForm1.btnEditClick(Sender: TObject); begin ListView1.EditMode := not ListView1.EditMode; (Sender as TButton).Text := 'EditMode '+ListView1.EditMode.ToString(TUseBoolStrs.True); end;
..and secondly show the selected items.
Each TListViewItem has a Checked property that can be queried to discover if the item is selected. Again using a simple look it is possible to check each item and then add it to a list that we will show.
procedure TForm1.btnShowSelectedClick(Sender: TObject);
var
SL : TStringList;
I: Integer;
begin
if ListView1.Items.CheckedCount = 0 then begin
ShowMessage('No selected items');
Exit;
end;
SL := TStringList.Create;
try
for I := 0 to ListView1.ItemCount -1 do begin
if ListView1.Items[I].Checked then
SL.Add(ListView1.Items[I].Text);
end;
ShowMessage('Items selected: '+SL.CommaText);
finally
SL.Free;
end;
end;
For simplicity in the code above I have used the TStringList.CommaText to give a formatted output of the data.
Ever wanted to take an Object into a format that is easily persisted and back? Well now you can. New in XE6 is the REST.JSON unit. This allows you access to TJSON a class with some very helpful class methods. Using TJSON you can convert an object to a JSON string and back with a little help from generics along the way.
The following code uses a class called TFoo that has a Foo and a Fee property (string and Integer) Using TJson you can then see how to covert the object to a string and back ready for storage, transport etc.
uses REST.JSON; // Also new System.JSON
procedure TForm1.Button1Click(Sender: TObject); var Foo: TFoo; begin Foo := TFoo.Create; try Foo.Foo := 'Hello World'; Foo.Fee := 42; Memo1.Lines.Text := TJson.ObjectToJsonString(Foo); finally Foo.Free; end; Foo := TJson.JsonToObject<TFoo>(Memo1.Lines.Text); try Foo.Fee := 100; Memo1.Lines.Add(TJson.ObjectToJsonString(Foo)); finally Foo.Free; end; end;
If you want to watch this being demo’ed this very show video shows it in action http://youtu.be/TSqWoFvjj5g