Use Java constant in GWT Javascript Overlay Type (JSO)?

Question

I would like to define the GWT JSO property name as a constant in the JSO, in order to avoid typos and benefit from Eclipse code completion, like so:

public final class MyJSO extends JavaScriptObject
{
    /** here is the constant */
    private static final String MY_CONST = "myPropName";

    protected MyJSO() {
        super();
    }

    public native void setMyProp(final boolean pFlag)
    /*-{
        this.@fully.qualified.MyJSO::MY_CONST = pFlag;
    }-*/;

    public native boolean isMyProp()
    /*-{
        if (this.hasOwnProperty(@fully.qualified.MyJSO::MY_CONST)) {
            return this.@fully.qualified.MyJSO::MY_CONST;
        } else {
            return false;
        }
    }-*/;
}

The GWT compiler should be able to replace the String from the constant at compile time, so there is no problem with the object living as Javascript later on.

But this is so totally not working, I'm thinking I may be wrong. :-) Can anyone explain why? Do you have better ideas how to achieve this?

Thanks!

score 4 · Accepted Answer · edited Apr 02 '14 at 08:32

4

The correct syntax to refer to a static variable is:

@fully.qualified.MyJSO::MY_CONST

No qualifier (this., in your example) is needed since the variable is static.

If you want to set/get a property on the JavaScript object with the constant name do so as follows:

public native void setMyProp(final boolean pFlag) /*-{
    this[@fully.qualified.MyJSO::MY_CONST] = pFlag;
}-*/;

public native boolean isMyProp() /*-{
    if (this[@fully.qualified.MyJSO::MY_CONST] != null) {
        return this[@fully.qualified.MyJSO::MY_CONST];
    } else {
        return false;
    }
}-*/;

edited Apr 02 '14 at 08:32

barfuin

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answered Dec 08 '11 at 22:59

Jason Terk

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Thanks! The hint that solved it was that I must use square brackets to access the property, not the dot notation. Using square brackets, my code works! The `hasOwnProperty` line can remain unchanged even. – barfuin Dec 09 '11 at 13:08
If only SO knew [nested syntax highlighting](http://meta.stackexchange.com/q/203205/205238) ... :-) – barfuin Apr 02 '14 at 08:33

Use Java constant in GWT Javascript Overlay Type (JSO)?

1 Answers1