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Salaam Ay-Lekum Muhammad. Welcome to the ranch. Before answering your query, I have a question of my own. What are you trying to do with this code? I do not understand the language in which you have written the instance variables/object names/text in SOPs. Also, it appears that you are new to Java language. Is it? Because this is a very basic doubt.
In lines 21, 22 and 23 you are creating three arrays-of-arrays, with size zero by zero, because at that point baris and kolom are zero.
You change the values of baris and kolom in lines 29 and 32 in the inputBarisKolom() method, but that ofcourse does not automatically change the size of matriksA, matriksB and matriksC. You'll have to re-initialize those with the correct size.