Nullpointer exception Java -


i beginner in java , have few problems null. need understanding following questions. have answered them correctly, not know exact reason behind them.

question:

suppose tracks has been declared type arraylist , consider following:

public track mostplayed() {     track = tracks.get(0);     int = 1;     while(i < tracks.size()) {         track t = tracks.get(i);         if (t.getplaycount() > most.getplaycount()) {              = t;         }         i++;     } return most; }

suppose nullpointerexception thrown during execution of mostplayed method. assuming single-threaded execution, 1 of following lines of code possible because of exception. one?

i had picked line 2 seemed logical answer, further explanation behind don't understand concept completely.

the line track = tracks.get(0); can throw nullpointerexception since code not show if track initialized. if not, null , there no method get in null (there no method @ all, actually).


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