I want to add a "search" icon to appear inside an
EditText in the left edge? such as search box in Facebook Android app?
You can set drawableLeft in the XML as suggested by marcos, but you might also want to set it programmatically - for example in response to an event. To do this use the method setCompoundDrawablesWithIntrincisBounds(int, int, int, int):
EditText editText = findViewById(R.id.myEditText); // Set drawables for left, top, right, and bottom - send 0 for nothing editTxt.setCompoundDrawablesWithIntrinsicBounds(R.drawable.myDrawable, 0, 0, 0);