android - Class casting and parentheses -


i have seen following code suggested number of times allowing fragment access variable in activity.

foo = ((mainactivity)this.getactivity()).getfoo();

now, if looked like:

foo = (mainactivity)this.getactivity().getfoo();

if make sense being cast (mainactivity), however, enclosing entire left side in parentheses exactly?

thanks much,

-john

just in maths, adding parentheses means "do first". in expression:

((mainactivity)this.getactivity()).getfoo();

we saying first:

(mainactivity)this.getactivity()

then on result of above, this:

.getfoo();

if don't have parentheses,

(mainactivity)this.getactivity().getfoo();

we saying first, since casting has low precedence:

this.getactivity().getfoo()

then cast result of above mainactivity.

obviously, latter expression not work because there no getfoo defined in activity, getactivity returns.


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