Getting compiler error while using array constants

问题:

public class Sonnet29 implements Poem {
    private String[] poem;
    public Sonnet29() {
        poem = { "foo", "bar" , "baz"};
    }
    @Override
    public void recite() {
      //...
    }
}

Line poem = { "foo", "bar" , "baz"}; is giving compilation error.

Any specific reason why this is not allowed? How do I initialize a String array with array constants?

EDIT: Thank you folks for your answers. Now I'm clear what is allowed and what is NOT. But can I ask you why this is NOT allowed?

String[] pets;
pets = {"cat", "dog"};

After googling a bit, I found this link, where in, it is told that coding like this leaves the compiler in ambiguity - whether the pets should be array of Strings or array of Objects. However from the declaration, it can very well figure out that it is a String array, right???

回答1:

This will do what you're looking for:

public Sonnet29() {
    poem = new String[] { "foo", "bar", "baz" };
}

Initialization lists are only allowed when creating a new instance of the array.

回答2:

From the Java language specification:

An array initializer may be specified in a declaration, or as part of an array creation expression (§15.10), creating an array and providing some initial values

In short, this is legal code:

private int[] values1 = new int[]{1,2,3,4};
private int[] values2 = {1,2,3,4}; // short form is allowed only (!) here

private String[][] map1 = new String[][]{{"1","one"},{"2","two"}};
private String[][] map2 = {{"1","one"},{"2","two"}}; // short form

List<String> list = Arrays.asList(new String[]{"cat","dog","mouse"});

and this is illegal:

private int[] values = new int[4];
values = {1,2,3,4}; // not an array initializer -> compile error

List<String> list = Arrays.asList({"cat","dog","mouse"}); // 'short' form not allowed

回答3:

{"cat", "dog"}

Is not an array, it is an array initializer.

new String[]{"cat", "dog"}

This can be seen as an array 'constructor' with two arguments. The short form is just there to reduce RSI.

They could have given real meaning to {"cat", "dog"}, so you could say things like

{"cat", "dog"}.length

But why should they make the compiler even harder to write, without adding anything useful? (ZoogieZork answer can be used easily)