Android Adapter Baseadapter Detailed

One of the three parameters of the GetView method is this

/**     * @param position      position is the position starting from 0     * @param convertview   Convertview is spinner, Each item in the ListView is displayed in the view     * @param the        parent is parented, which is Spinner,listview,gridview     * @return              Usually the return view is Convertview     * The content of the drawing is implemented here *        /Abstract public View getView (int position, view Convertview, ViewGroup parent);

Call GetView () to draw each row one by one. If your GetCount () return value is 0, the list will not be displayed, and the same return 1 will show only one row. When the system displays the list, first instantiate an adapter (this will instantiate the custom adapter). When you manually complete the adaptation, you must manually map the data, which requires overriding the GetView () method. This method is called when the system draws each row of the list. GetView () has three parameters, position indicates that the first line will be displayed, Covertview is the layout inflate from the layout file. We use the Layoutinflater method to extract the well-defined Item.xml file into a view instance for display. The individual components in the XML file are then instantiated (the Simple Findviewbyid () method). This allows the data to be mapped to individual components. However, in order to respond to a click event, the button needs to be added a click Listener to capture the click event. Now that a custom ListView has been completed, let's go back and look at the process from a new perspective. System to draw the ListView, he first obtains the length of the list to be drawn, and then begins to draw the first line, how to draw it? Call the GetView () function. In this function, we first get a view (actually a viewgroup) and then instantiate and set up each component to show it. Well, finish drawing this line. Then draw the next line until the painting is finished.

Android Adapter Baseadapter Detailed