Question

1. what is the difference between: String a[] and List<String> a?
2. Is String a[] correct? or for defining array of strings we should use String[] a always?
3. When we declare String[] a, do we need to initialize it always?

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Suppose i do this:

String[] a = new String[5];
a[2] = "Hello";
a[3] = "World";
a[2] = "Good Bye";

Since array is stored contiguously in memory and when i modify a string new string object is created. How does all these strings stored and modified in Java for all of the above statements?

Answer 1

1. String a[] is a native Java array of Strings. List a is a raw (untyped) List (see The Java Collections). You probably want the genericised version: List<String> a. There are far too many differences to list here; you should follow that link!
2. String a[] and String[] a are equivalent. String[] a is the convention, though.
3. String[] a is actually a reference. If it’s a non-local variable, it will be implicitly initialised to null if you don’t explicitly initialise it. You commonly will want to do something like String[] a = new String[10];.
4. Each element of the array is a reference to a String; the underlying data itself is not stored in the array.