Jsinterop: java arrays, native arrays, JsArray and strings

Hi,

I want to know if a java array is the same underlying object with a js native array.

    @JsType(isNative = true, namespace = JsPackage.GLOBAL, name = "Object")
    public static class MyObject {
        int x;
       
        @JsOverlay
        public static MyObject create(int x) {
            final MyObject o = new MyObject();
            o.x = x;
            return o;
        }
    }

    @Override
    public void onModuleLoad() {
        // check if java arrays are implemented by the same underlying native array
        final MyObject[] java_array = new MyObject[] { MyObject.create(1), MyObject.create(4), MyObject.create(16) };
        DomGlobal.console.log((Object) java_array);
        // cast to nativeJsArray<double>
        final JsArray<MyObject> js_array = Js.uncheckedCast(java_array);
        DomGlobal.console.log(js_array);
        // delete second object
        // DomGlobal.window.alert("Check this out");
        js_array.splice(1, 1);
        DomGlobal.console.log((Object) java_array);
        DomGlobal.console.log(js_array);

        return;

   }

Results:

Array(3) [ {…}, {…}, {…} ]

Array(3) [ {…}, {…}, {…} ]

Array [ {…}, {…} ]

Array [ {…}, {…} ]

So the splice call succeeds and I can remove elements from the java array. Cool. So this is evidence that java arrays are backed by js arrays,

So

• Arrays, double are mapped to native types.
• We have @JsFunction and Function
• int is mapped to js number --> double

Is it possible to also map java.lang.String to native JsString

        final JsString x1 = new JsString("x1");
        DomGlobal.console.log(x1);
        final String x2 = Js.uncheckedCast(x1);
        DomGlobal.console.log((Object) new String[] {x2});
        final String x3 = x2.replaceAll("1", "3");
        DomGlobal.console.log((Object) new String[] {x3});
        return;

Results:

String { "x1" } <- native js string

Array [ String ] <-- java clas String with value "x1"

Array [ "x3" ] <- native js string ???? Why?

I don't really understand the results. Any comment?

--

Vassilis Virvilis

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