How to memorize a diode's polarity in symbol? (self-answered)
Two mnemonic technique I'll mention. Both technique I've learnt from someone else, many-years ago.


We can easily remember, anode is abbreviated as A, and Cathode as K. That is standard, and easy to remember.


Now , Write a K



Now, just fill in the blanks to make it a diode.



Now , the side of diode, where K was drawn, is Cathode (K).

By default, the opposite side is anode (A).

Now, if once we learn to recognize the K, if the diode orientate to a different direction in the diagram,  we could easily identify the anode and cathode.



-----------------------------------------------------------------


The triangle inside the diode, makes an arrow sign. That tells the direction of allowed-direction of current.




From the second-method , we-can easily remember, the direction of current.

And ow.  A selected portion of Circuit portion(portion of interest)(here diode)'s  Cathode is the electrode that Vomits out-out positive-charge; 

and the circuit's portion-of-interest(here diode)'s  Anode is the electrode that Sucks-in the positive charge.



above-table: Anode-Cathode Vs Plus-Minus Disambiguation

That is applicable not only for diodes. It is applicable for any-components like Electrochemical (Battery)-Cell, , Electrolytic-cell, Cathode-ray-Tube(CRT), etc. 



Circuit's portion-of-interest(here diode)'s  Anode is to be attached with circuit-counterpart(here battery)'s Cathode. 

And Circuit's portion-of-interest(here diode)'s Cathode to be attached with circuit's Counterpart(here battery)'s Anode.

Within the circuit's portion of interest (Here it is diode), Current flows in its Anode to Cathode direction.

In that selected portion's counterpart, or outer-portion of the path,  current flows from Anode(of the selected part, here diode) to Cathode ( of the selected part, here diode).