Question

Basically how do you check if an object is null or empty. What I mean is that if I have an object instantiated but all its values or fields are null, the how do I check in code if it is empty?

I have tried;

if (doc != null){
.... do something

But it doesn’t seem to work.

Answer 1

You can’t do it directly, you should provide your own way to check this. Eg.

class MyClass {
  Object attr1, attr2, attr3;

  public boolean isValid() {
    return attr1 != null && attr2 != null && attr3 != null;
  }
}

Or make all fields final and initialize them in constructors so that you can be sure that everything is initialized.