Converting a Javascript array to a Java array

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爱一瞬间的悲伤
爱一瞬间的悲伤 2021-01-20 17:38

I\'m trying to convert a Javascript array in Java to a Java array. I\'m using the javax.script package. I tested this example here, but the type \"NativeArray\" was not reco

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  • 2021-01-20 18:01

    Rhino offers this:

    https://developer.mozilla.org/en-US/docs/Mozilla/Projects/Rhino/Embedding_tutorial#usingJSObjs

    Also Scriptable interface offers get() and set() so you can easily enumerate the properties of an object and add it to an array:

    Scriptable arr = (Scriptable) result;
    Object [] array = new Object[arr.getIds().length];
    for (Object o : arr.getIds()) {
       int index = (Integer) o;
       array[index] = arr.get(index, null);
    }
    

    Same thing but not using NativeArray since that appears to be a Rhino specific thing. You could easily drop a breakpoint and see what type of object you were given then downcast to that. It's some sort of JS Array implementation that's pretty close to NativeArray.

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  • 2021-01-20 18:12

    I would simply use json-lib and parse the array that way. for example see How to parse a JSON and turn its values into an Array?

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  • 2021-01-20 18:24

    I would recommend Doug Crockfords JSON-java library. This allows you to convert json to native JAVA objects.

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  • 2021-01-20 18:25

    Per this answer it looks like your best bet is to write a JavaScript converter function which transforms the native JavaScript array into a Java array using Rhino's Java binding functionality. Note that you'll have to take some care to use the correct type when converting the individual elements.

    [Edit] Here's a working example using a string array:

    ScriptEngine js = new ScriptEngineManager().getEngineByName("JavaScript");
    String ss[] = (String[]) js.eval(
        "(function() {" +
        "  var a = java.lang.reflect.Array.newInstance(java.lang.String, 3);" +
        "  a[0] = 'foo';" +
        "  a[1] = 'bar';" +
        "  a[2] = 'gah';" +
        "  return a;" +
        "})()");
    System.out.println(Arrays.toString(ss)); // => [foo, bar, gah]
    
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