android - How to know what 'this' keyword refers to when reading any codes? -

i'm learning android. i've known this keyword when creating constructor. however, still confusing me know this refers in other situations.

specifically, when reading code examples, in methods, passed in this parameter, , dont know this means cannot replicate code later uses.

please intruct me should find out reference 'this' when reading code or giving parameter 'this'.

thank much!

see example:

    public class example_5 extends appcompatactivity {      listview lv5;     list<country> countries;      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_example_5);          lv5 = (listview) findviewbyid(r.id.lv5);          countries = new arraylist<>();         countries.add(new country("vietnam", "việt nam", r.drawable.flag_vi));         countries.add(new country("laos", "lào", r.drawable.flag_fr));         countries.add(new country("japan", "nhật bản", r.drawable.flag_jp));         countries.add(new country("usa", "mỹ", r.drawable.flag_us));           countryadapter3 adapter3 = new countryadapter3(this, countries, r.layout.item_layout_3);         lv5.setadapter(adapter3);       }   } 

do this:

toast.maketext(this, this.getclass().tostring(), toast.length_short).show(); 

you see class name