Better syntax for Java array

[slavchev]

NativeScript for Android does not provide syntax to create Java array from JavaScript. The current way is quite verbose and not intuitive. For example

var arr = java.lang.reflect.Array.newInstance(java.lang.Byte.class.getField("TYPE").get(null), 10);
// arr = new byte[10];

There are a few suggestions.

1. var arr = array([ "element1", "emelemt2", ...]); This will work for only scenarios where we can deduce the element type.
2. var arr = array("byte", 10) The first parameter is type name, the second parameter is length.
3. extends the built-in Array with fromJavaType or whatever. For example var arr = Array.fromJavaType("byte", 10);
4. same as 3) but provide custom object. For example var arr = JavaArray.create("byte", 10);
5. same as 4) but add type specializations as well. For example: var arr = JavaArray.createByteArray(10);
6. reuse existing "cast" functions for primitive types. For example var arr = new byte(10);. This scenario does not work for reference types, so should be combined with another one.

Any other suggestions are welcome.

Note: suggested syntax that fits TypeScript well have advantage.

[vakrilov]

Suggestion 5) looks most explicit to me for primitive types. For reference types we would have to have a method that accepts type parameter.

[hshristov]

+1 for point 4 - var arr = JavaArray.create("byte", 10);
Where byte is the full name of the type. In my opinion most of the time we will use it with primitive types so it will be easier if byte, int are allowed as type specifiers.

[blagoev]

I suggest this syntax to be only for arrays of reference types. Primitive arrays should be covered by the typed arrays support. #65

[blagoev]

suggest using Array.of syntax similar to this: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/of

Array.of(android.view.View, 20)

we can monkey patch this as this:
if (!Array.of) {
Array.of = function() {
return Array.prototype.slice.call(arguments);
};
}

so it will be
Array.of = function(type, number) {
return java.lang.reflect.Array.newInstance(type.class, number);
}

actually I think I just implemented it in this comment. That's called "in comment driven development" :)

[blagoev]

We can create globals.js or use our prepareExtends.js to include js functions like this.

[slavchev]

I would be confused to use Array.of to create Java objects. If I read the docs correctly

Array.of(element0[, element1[, ...[, elementN]]])

it would create JavaScript array [element0<, element1,...>]. Let's keep it that way and don't change the standard JavaScript features.

[blagoev]

Consider this as a better variant of Array.fromJavaType. So to take the best of both I suppose Array.ofJavaType is better. The "from" implies an iteratable objects in Javascript

[blagoev]

Also consider this syntax
Array.create(android.view.View, 20);

[slavchev]

I am fine with Array.create. The point is to avoid any breaking change. For example if you currently run

var a = Array.of(java.lang.Object, 10);
console.log("a.length=" + a.length);

it will print 2 as expected. So, in short Array.create sounds good to me.

[atanasovg]

+1 for Array.create(type, count)