ArrayList initialization equivalent to array initialization

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Create ArrayList from array 32 answers

Initialization of an ArrayList in one line 32 answers

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Arrays.asList可以在这里帮助：

new ArrayList<Integer>(Arrays.asList(1,2,3,5,8,13,21));

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Yes.

new ArrayList<String>(){{
   add("A");
   add("B");
}}

What this is actually doing is creating a class derived from ArrayList<String> (the outer set of braces do this) and then declare a static initialiser (the inner set of braces). This is actually an inner class of the containing class, and so it'll have an implicit this pointer. Not a problem unless you want to serialise it, or you're expecting the outer class to be garbage collected.

I understand that Java 7 will provide additional language constructs to do precisely what you want.

EDIT: recent Java versions provide more usable functions for creating such collections, and are worth investigating over the above (provided at a time prior to these versions)

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Here is the closest you can get:

ArrayList<String> list = new ArrayList(Arrays.asList("Ryan", "Julie", "Bob"));

You can go even simpler with:

List<String> list = Arrays.asList("Ryan", "Julie", "Bob")

Looking at the source for Arrays.asList, it constructs an ArrayList, but by default is cast to List. So you could do this (but not reliably for new JDKs):

ArrayList<String> list = (ArrayList<String>)Arrays.asList("Ryan", "Julie", "Bob")

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