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dapm:laboratoare:05 [2018/03/23 14:26] ioana_maria.culic |
dapm:laboratoare:05 [2021/04/10 21:03] (current) ioana_maria.culic |
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| - | ===== Laboratorul 05. ===== | + | ===== Lab 06 - Lists ===== |
| === LISTS === | === LISTS === | ||
| - | Lists fara, cu reciclare, tag | + | In android, an adapter is a bridge between UI component and data source that helps us to fill data in the UI component. It holds the data and send the data to adapter view then view can takes the data from the adapter view and shows the data on different views like as list view, grid view, spinner etc\\ |
| - | list, base adapter | + | |
| - | + | ||
| - | **Ex 1** Make a new project and do not generate a xml file. If you have generated a xml file, delete it.\\ | + | |
| - | Then, add a new xml file named activity_main.xml and make it a LinearLayout with __width match_parent__ and__ height wrap_content__ with the __orientation horizontal__. In it, add a **ListView** with __width and height match_parent__ \\ | + | |
| - | + | ||
| - | **Ex 3** Create another xml file (a LinearLayout ) named list_item.xml. The __orientation__ shoud be __horizontal__ and the __width and the height__ shoud be wrap___content__.\\ | + | |
| - | In the LinearLayout, add an **ImageView**(with id iv_image_element) and a **TextView**(with id tv_name_element), both with width and height wrap_content. | + | |
| \\ | \\ | ||
| - | **Ex 3** In the MainActivity.java file create another 2 classes (not in class MainActivity): __class Car__ with a String name, and a int imageResource and another __class__ named __TagCar__ with a TextView name and a ImageView image. | + | BaseAdapter methods:\\ |
| + | 1. getCount(): The getCount() function returns the total number of items to be displayed in a list. It counts the value from array list size() method or an array’s length.\\ | ||
| \\ | \\ | ||
| - | In the onCreate function, connect the ListView from the java to the xml (1), and initializate the object carAdapter(2) and set the carAdapter adapter for list of cars (3) | + | 2. getView(int i, View view, ViewGroup viewGroup): This function is automatically called when the list item view is ready to be displayed or about to be displayed. In this function we set the layout for list items using LayoutInflater class and then add the data to the views like ImageView, TextView etc\\ |
| - | + | ||
| - | public class MainActivity extends Activity { | + | |
| - | private ListView listOfCars; | + | |
| - | CarAdapter carAdapter; | + | |
| - | + | ||
| - | @Override | + | |
| - | protected void onCreate(Bundle savedInstanceState) { | + | |
| - | super.onCreate(savedInstanceState); | + | |
| - | setContentView(R.layout.activity_main); | + | |
| - | // TODO 1, 2, 3 | + | |
| - | } | + | |
| - | } | + | |
| \\ | \\ | ||
| - | + | 3. getItem(int i): This function is used to Get the data item associated with the specified position in the data set to obtain the corresponding data of the specific location in the collection of data items.\\ | |
| - | **Ex 4** Create a new java file named CarAdapter which extends BaseAdapter. In it, add an Activity object named context, and an ArrayList of Car named cars\\ | + | |
| - | Implement the 4 methods, and in the getView function add this text: | + | |
| - | public View getView(int i, View view, ViewGroup viewGroup) { | + | |
| - | View element; | + | |
| - | + | ||
| - | LayoutInflater layoutInflater = context.getLayoutInflater(); | + | |
| - | element = layoutInflater.inflate(R.layout.list_item, null); | + | |
| - | TagCar car = new TagCar(); | + | |
| - | car.name = element.findViewById(R.id.tv_name_element); | + | |
| - | car.image = element.findViewById(R.id.iv_image_element); | + | |
| - | element.setTag(car); | + | |
| - | + | ||
| - | TagCar tag = (TagCar) element.getTag(); | + | |
| - | tag.name.setText(cars.get(i).name); | + | |
| - | tag.image.setImageResource(cars.get(i).imageResource); | + | |
| - | return element; | + | |
| - | } | + | |
| - | **Look in Course 4 - List, adapters, recylcing slides 29-31 and tell the teaching assistant if this method is efficient or not (if it's not, make it efficient).** | + | |
| \\ | \\ | ||
| + | 4. getItemId(int i): As for the getItemId (int position), it returns the corresponding to the position item ID. The function returns a long value of item position to the adapter.\\ | ||
| + | \\ | ||
| + | |||
| + | |||
| + | |||
| + | ====== Exercises ====== | ||
| + | |||
| + | Create a new project and follow the next tutorial http://abhiandroid.com/ui/baseadapter-tutorial-example.html. | ||
