Android :: Android Date Picker To Input Value Instead Of Keyboard?

I am attempting to learn Android development and have modified a sample app that loads a web page in a WebView. The web page contains a text input. I want to use the Android DatePicker to input a value instead of the keyboard. The code below almost works. The DatePicker is displayed but throws an unknown error when I select a date and call loadUrl on the WebView in the onDateSet handler to update the value of the text input (end of code sample). I suspect a cross thread issue but I'm not sure.

package com.freeze.android.hellowebview;
import java.util.Calendar;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.Dialog;
import android.os.Bundle;
import android.view.KeyEvent;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.DatePicker;

public class HelloWebView extends Activity { WebView webview;
class DateJavaScriptInterface { public void pickDate() { showDialog(0);
} } public void loadScript(String script){
webview.loadUrl("javascript:(function() { " + script + "})()");
} private class HelloWebViewClient extends WebViewClient {
@Override public boolean shouldOverrideUrlLoading(WebView view, String url)
view.loadUrl(url); return true;
} @Override public void onPageFinished(WebView view, String url) {
loadScript("document.getElementById('trips_dateandtime').onfocus = function(
{this.blur();window.DateInterface.pickDate();};");
} } /** Called when the activity is first created. */
@Override public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); setContentView(R.layout.main);
webview = (WebView) findViewById(R.id.webview);
webview.setWebViewClient(new HelloWebViewClient());
webview.getSettings().setJavaScriptEnabled(true);
webview.addJavascriptInterface(new DateJavaScriptInterface(), "DateInterface");
webview.loadUrl("http://127.0.0.1:8000/mileage/default/index");
} @Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
if ((keyCode == KeyEvent.KEYCODE_BACK) && webview.canGoBack()) {
webview.goBack(); return true;
} return super.onKeyDown(keyCode, event);
} @Overrid protected Dialog onCreateDialog(int id) {
switch (id) { case 0:
final Calendar c = Calendar.getInstance();
int mYear = c.get(Calendar.YEAR);
int mMonth = c.get(Calendar.MONTH);
int mDay = c.get(Calendar.DAY_OF_MONTH);
return new DatePickerDialog(this,
mDateSetListener, mYear, mMonth, mDay);
} return null;
} private DatePickerDialog.OnDateSetListener mDateSetListener =
new DatePickerDialog.OnDateSetListener() {
@Overrid public void onDateSet(DatePicker view, int year, int monthOfYear, int dayOfMonth) {
loadScript("document.getElementById('trips_dateandtime').value = 'test';"); //ERROR
} };
}