null vector means the JVM doesn't allocate memory.It doesn't existin memory. NO instance!empty vector means the JVM allocated memory.It exists in memory.it's a instance than is accessabel.But only have on elements.GL&HF.
Imagine a blank sheet of paper. This is an empty vector. Now imagine NOT a sheet of paper. This is a null vector.We encounter this even in reality: sometimes we need a name for something which doesn't just exist.