get the context from an non-activity class into a non-activity

I'd like to get access from my database which is the DBAdapter.class (not an activity) into another non-activity class that randoms data RandomData.class

my sample code was like:

DBAdapter getAvailRandom=new DBAdapter(getApplicationContext());
 getAvailRandom.open();
 ...
 ....
 ...

 getAvailRandom.close();

getApplicationContext() is always undefined

I tried getActivity.getApplicationContext() and Activity.this , but still not working