Injecting Javascript Into A Webview Outside The Onpagefinished Event (using Datepicker To Set A Date On An Input Of A Webview)

I have an Android app, running a WebView that loads a certain page, also part of the app. I want to use the Android DatePicker to get a date from the user and set the value on an i

Solution 1:

Thanks @CommonsWare for the comment, i tracked the error and got this:

"android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views."

Googled it and got this forum thread

So, in order to update a view in the UI at runtime and outside it's thread, you have to use a Handler, that receive messages and execute actions accordingly.

So i implemented a Handler for the Activity, that gets a message with an int identifier and the data i want to update into the webview:

finalHandlerhandler=newHandler() {
    publicvoidhandleMessage(Message msg) {

        intcod= msg.getData().getInt("messageType");
        switch(cod){
            case1:
                Stringdate= msg.getData().getString("datePickerValue");
                mWebView.loadUrl("javascript:setReturnDate('" + mId + "', '" + date + "');");
                break;
            case2:
                showDialog(0);
                break;
        }

    }
};

I had to change the openDatePicker method of the class to use the Handler, as well as create an input parameter, which is the id of the control in the page:

publicvoidopenDatePicker(String id){

        mId = id; //mId is a string declared in the Activity scope, so it can be used anywhereMessagemsg=newMessage();
        Bundleb=newBundle();
        b.putInt("messageType", 2);

        msg.setData(b);
        handler.sendMessage(msg);
    }

Rewrote the DatePicker listener for the date selection, to get the data and send a message to the Handler:

private DatePickerDialog.OnDateSetListenermDateSetListener=newDatePickerDialog.OnDateSetListener() {

        publicvoidonDateSet(DatePicker view, int year, 
                              int monthOfYear, int dayOfMonth) {

            Messagemsg=newMessage();
            Bundleb=newBundle();
            b.putInt("messageType", 1);
            b.putString("datePickerValue", 
                    String.format("%02d", dayOfMonth) + "/" + 
                    String.format("%02d", (monthOfYear + 1)) + "/" + 
                    String.valueOf(year));
            msg.setData(b);
            handler.sendMessage(msg);
        }
    };

In the webpage, the js functions got out like this:

function openDatePicker(id) {
        if (objAndroid != null) objAndroid.openDatePicker(id);
    }

    function setReturnDate(id, date) {
        var obj = document.getElementById(id);
        if (obj != null)
            obj.value = date;
    }

And finally, the input (TextBox), got like this:

TextBox obj = FindControl("txtDt") as TextBox;

            if (obj != null)
            {
                obj.Attributes.Add("readonly", "readonly");
                obj.Attributes.Add("OnClick", "javascript:openDatePicker(this.id)");
            }