Initialising An ArrayList

2018-06-09 05:25:19

This question already has an answer here:

Initialization of an ArrayList in one line 32 answers

This depends on what you mean by initialize. To simply initialize the variable time with the value of a reference to a new ArrayList , you do

ArrayList<String> time = new ArrayList<String>();

(replace String with the type of the objects you want to store in the list.)

If you want to put stuff in the list, you could do

ArrayList<String> time = new ArrayList<String>();
time.add("hello");
time.add("there");
time.add("world");

You could also do

ArrayList<String> time = new ArrayList<String>(
    Arrays.asList("hello", "there", "world"));

or by using an instance initializer

ArrayList<String> time = new ArrayList<String>() {{
    add("hello");
    add("there");
    add("world");
}};

Arrays.asList allows you to build a List from a list of values.

You can then build your ArrayList by passing it the read-only list generated by Arrays.asList .

ArrayList time = new ArrayList(Arrays.asList("a", "b", "c"));

But if all you need is a List declared inline, just go with Arrays.asList alone.

List time = Arrays.asList("a", "b", "c");

ArrayList<String> time = ArrayList.class.newInstance();

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