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ArrayList null pointer exception in Java

You can't add elements to your list without instantiating it (it's null)

public ArrayList<DisplayMode>
list = new ArrayList<>();

I suggest you use the List interface. Also, Java naming convention would be MyClass and you could initialize list in the constructor with Arrays.asList(T...) (which I suggest you not make public) like

private List<DisplayMode> list;
public MyClass() {
  list = new

Categories : Java

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