How to create icon for Android apps

Context context = getApplicationContext();
String DB_PATH = "/data/data/"
                + context.getPackageName()
                + "/databases/";

<include  layout="@layout/my_layout" android:id="@+id/idMyLayout" />

<ListView android:id="@+id/idListView"
        android:background="#7700CC00"
        android:layout_height="wrap_content"
        android:layout_width="fill_parent" /> 

public class Main extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        ListView mlistView = (ListView) findViewById(R.id.idListView);
        mlistView.setAdapter(new ArrayAdapter<String>(this,
                android.R.layout.simple_list_item_1, 
                new String[] {"Game", "Help", "Home site"}));
    
        mlistView.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
              // When clicked, show a toast with the TextView text Game, Help, Home
              Toast.makeText(getApplicationContext(), ((TextView) view).getText(),
                  Toast.LENGTH_SHORT).show();
            }
          });
     }
}

// you can put this text into some function body or case in switch statement
                new AlertDialog.Builder(this)
                    .setMessage("Hello boys!!!")
                    .setPositiveButton("OK", null)
                    .show();

Context context = getApplicationContext();
	AlertDialog.Builder builder = new AlertDialog.Builder(context);
	builder.setTitle("Select font size");
	final CharSequence[] chsSize= { "Small", "Medium", "Large"};
	builder.setSingleChoiceItems(chsSize, 0 /*sel.item*/, 
	new DialogInterface.OnClickListener() {
 	    public void onClick(DialogInterface dialog, int item) {
	    		 Toast.makeText(context, "Hello from dialog!!!", Toast.LENGTH_SHORT).show();
	        dialog.dismiss();
	    }
	});
	AlertDialog alert = builder.create();
	alert.show();
    

// warnning
private List list = new ArrayList();

// ok /put type of added object
private List<String> list = new ArrayList<String>();