[C#] 개체 참조가 개체의 인스턴스로 설정되지 않았습니다.

Q.
ArrayList[] j = new ArrayList[4];
which gave me some nullPointer errors when I tried to add items to j[0].


A.
all the entries from your array will be pointing to null instead of an ArrayList.
After you create an array, you could loop through it and assign an ArrayList to each entry, that way you will not have those nasty null-pointer exceptions. Example:

ArrayList[] myList = new ArrayList[4];

for(int i = 0; i < myList.length; i++) {
    myList[i] = new ArrayList();
}

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ㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎㅎ
ㅓ허허허허허허ㅓ허허ㅓ허허헣허허허허헣
그런것이었다.


출처 : http://sdeva.tistory.com/entry/%EC%98%A4%EB%8A%98%EC%9D%98-%EC%82%BD%EC%A7%88-%EA%B0%9C%EC%B2%B4-%EC%B0%B8%EC%A1%B0%EA%B0%80-%EA%B0%9C%EC%B2%B4%EC%9D%98-%EC%9D%B8%EC%8A%A4%ED%84%B4%EC%8A%A4%EB%A1%9C-%EC%84%A4%EC%A0%95%EB%90%98%EC%A7%80-%EC%95%8A%EC%95%98%EC%8A%B5%EB%8B%88%EB%8B%A4