Creating UI widgets from pure Java without XML

We can also create widgets from Java objects that are not a reference to an object in our layout. We can declare, instantiate, and set a widget's attributes all in code, as follows:

Button myButton = new Button();

The preceding code creates a new Button by using the new() keyword. The only caveat is that the Button has to be part of a layout before it can be seen by the user. So, we could either get a reference to a layout element from our XML layout or create a new one, in code.

If we assume that we have a LinearLayout in our XML with an id property equal to linearLayout1, we could put our Button from the earlier line of code into it, as follows:

// Get a reference to the LinearLayout
LinearLayout linearLayout = (LinearLayout)
   findViewById(R.id.linearLayout);
// Add our Button to it
linearLayout.addView(myButton);

We could even create an entire layout in pure Java code by, first, creating a new layout...