Innovation is Our Culture
Android is now over five years old and despite the little green robot android peeking out of phone shops up and down the highstreet, there are still those who don’t know what it is or what it’s all about.
I’ve come to discover that people who struggle to code don’t just struggle on big problems, or even smallish problems (i.e. write a implementation of a linked list). They struggle with tiny problems.
Design patterns represent the best practices used by experienced object-oriented software developers. Design patterns are solutions to general problems that software developers faced during software development.
Highly praised tutorial will explain everything in detail to cater to both beginners and advanced programmers alike. When you walk away from this course, you will have created the above game in Java and ported it to Android.
Web services are open standard ( XML, SOAP, HTTP etc.) based Web applications that interact with other web applications for the purpose of exchanging data
@Override protected void onCreate(Bundle bundle) { super.onCreate(bundle); // window features - must be set prior to calling setContentView... requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(PanelBuilder.createList(this)); }PanelBuilder is a static class with helper methods to assemble the ListView and it’s underlying adapter:
public static View createList(Activity activity) { // create the ui components LinearLayout mainpanel = new LinearLayout(activity); ListView listview = new ListView(activity); // setup the mainpanel { // apply view group params for the activity's root pane LayoutUtils.Layout.WidthFill_HeightFill.applyViewGroupParams(mainpanel); // set animation layout on the mainpanel AnimUtils.setLayoutAnim_slideupfrombottom(mainpanel, activity); } // setup the listview and add to the mainpanel { LayoutUtils.Layout.WidthFill_HeightFill.applyLinearLayoutParams(listview); bindListViewToAdapter(activity, listview); AnimUtils.setLayoutAnim_slidedownfromtop(listview, activity); mainpanel.addView(listview); } // return the mainpanel return mainpanel; }Some notes on the code:
/** create the list data, and bind a custom adapter to the listview */ private static void bindListViewToAdapter(Activity ctx, ListView listview) { final WeatherDataListAdapter listModelView = new WeatherDataListAdapter(ctx, listview); // bind a selection listener to the view listview.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() { public void onItemSelected(AdapterView parentView, View childView, int position, long id) { listModelView.setSelected(position); } public void onNothingSelected(AdapterView parentView) { listModelView.setSelected(-1); } }); }Some notes on the code:
public class WeatherDataListAdapter extends BaseAdapter { //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX // data members //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX /** holds all the weather data */ private Hashtable<String, Hashtable<String, String>> _data = new Hashtable<String, Hashtable<String, String>>(); /** holds the currently selected position */ private int _selectedIndex; private Activity _context; //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX // constructor //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX /** * create the model-view object that will control the listview * * @param context activity that creates this thing * @param listview bind to this listview */ public WeatherDataListAdapter(final Activity context, ListView listview) { // save the activity/context ref _context = context; // bind this model (and cell renderer) to the listview listview.setAdapter(this); // load some data into the model { String zip = "12345"; Hashtable<String, String> wd = new Hashtable<String, String>(); wd.put("temperature","30F"); wd.put("humidity","50%"); wd.put("icon","12"); _data.put(zip, weatherdata); } Log.i(getClass().getSimpleName(), "loading data set, creating list model, and binding to listview"); } //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX // implement ListAdapter - how big is the underlying list data, and how to iterate it... // the underlying data is a Map of Maps, so this really reflects the keyset of the enclosing Map... //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX /** returns all the items in the {@link #_data} table */ public int getCount() { return _data.size(); } /** returns the key for the table, not the value (which is another table) */ public Object getItem(int i) { Object retval = _data.keySet().toArray()[i]; Log.i(getClass().getSimpleName(), "getItem(" + i + ") = " + retval); return retval; } /** returns the unique id for the given index, which is just the index */ public long getItemId(int i) { return i; }Notes on the code:
//XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX // handle list selection //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX /** * called when item in listview is selected... fires a model changed event... * * @param index index of item selected in listview. if -1 then it's unselected. */ public void setSelected(int index) { if (index == -1) { // unselected } else { // selected index... } _selectedIndex = index; // notify the model that the data has changed, need to update the view notifyDataSetChanged(); Log.i(getClass().getSimpleName(), "updating _selectionIndex with index and firing model-change-event: index=" + index); }Notes on the code:
//XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX // custom cell renderer //XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX @Override public View getView(int index, View cellRenderer, ViewGroup parent) { CellRendererView cellRendererView = null; if (cellRenderer == null) { // create the cell renderer Log.i(getClass().getSimpleName(), "creating a CellRendererView object"); cellRendererView = new CellRendererView(); } else { cellRendererView = (CellRendererView) cellRenderer; } // update the cell renderer, and handle selection state cellRendererView.display(index, _selectedIndex == index); return cellRendererView; }Notes on the code:
/** this class is responsible for rendering the data in the model, given the selection state */ private class CellRendererView extends TableLayout { // ui stuff private TextView _lblName; private ImageView _lblIcon; private TextView _lblDescription; public CellRendererView() { super(_context); _createUI(); } /** create the ui components */ private void _createUI() { // make the 2nd col growable/wrappable setColumnShrinkable(1, true); setColumnStretchable(1, true); // set the padding setPadding(10, 10, 10, 10); // single row that holds icon/flag & name TableRow row = new TableRow(_context); LayoutUtils.Layout.WidthFill_HeightWrap.applyTableLayoutParams(row); // fill the first row with: icon/flag, name { _lblName = new TextView(_context); LayoutUtils.Layout.WidthWrap_HeightWrap.applyTableRowParams(_lblName); _lblName.setPadding(10, 10, 10, 10); _lblIcon = AppUtils.createImageView(_context, -1, -1, -1); LayoutUtils.Layout.WidthWrap_HeightWrap.applyTableRowParams(_lblIcon); _lblIcon.setPadding(10, 10, 10, 10); row.addView(_lblIcon); row.addView(_lblName); } // create the 2nd row with: description { _lblDescription = new TextView(_context); LayoutUtils.Layout.WidthFill_HeightWrap.applyTableLayoutParams(_lblDescription); _lblDescription.setPadding(10, 10, 10, 10); } // add the rows to the table { addView(row); addView(_lblDescription); } Log.i(getClass().getSimpleName(), "CellRendererView created"); } /** update the views with the data corresponding to selection index */ public void display(int index, boolean selected) { String zip = getItem(index).toString(); Hashtable<String, String> weatherForZip = _data.get(zip); Log.i(getClass().getSimpleName(), "row[" + index + "] = " + weatherForZip.toString()); String temp = weatherForZip.get("temperature"); String icon = weatherForZip.get("icon"); int iconId = ResourceUtils.getResourceIdForDrawable(_context, "com.developerlife", "w" + icon); String humidity = weatherForZip.get("humidity"); _lblName.setText("Feels like: " + temp + " F, in: " + zip); _lblIcon.setImageResource(iconId); _lblDescription.setText("Humidity: " + humidity + " %"); Log.i(getClass().getSimpleName(), "rendering index:" + index); if (selected) { _lblDescription.setVisibility(View.VISIBLE); Log.i(getClass().getSimpleName(), "hiding descripton for index:" + index); } else { _lblDescription.setVisibility(View.GONE); Log.i(getClass().getSimpleName(), "showing description for index:" + index); } } }Notes on this code:
boolean t;
byte b;
char c;
int i;
long l;'t' is declared as boolean type, and 'b' as of byte type, etc.int type, can be stored in a 32 bit hardware register.public class pSimpleObject{
int i;
public pSimpleObject(){
i = 0;
}
public int get(){
return i;
}
public void set(int n){
i = n;
}
}public, this means that it can be visible to other objects outside it's file. We later say that it's a class, and give it's name, which in this case is: pSimpleObject. Inside of it, the class contains an integer named 'i', and three functions. The first function named pSimpleObject(), is the constructor. It is called every time an object is created using this class. The set() and get() functions set and get the value of 'i' respectively. One useful terminology is that functions in objects are not called functions, they're called methods. So, to refer to function set(), you'd say "method set()." That's all there is to objects!pSimpleObject myObject;
myObject = new pSimpleObject();pSimpleObject myObject = new pSimpleObject();myObject, of class pSimpleObject, and later instantiate it (a process of actual creation, where it calls the object's constructor method). The second approach illustrates that it all can be done in one line. The object does not get created when you just declare it, it's only created when you do a new on it.
