David Chandler's Journal of Java Web and Mobile Development

  • David M. Chandler

    Web app developer since 1994 and Google Cloud Platform Instructor now residing in Colorado. Besides tech, I enjoy landscape photography and share my work at ColoradoPhoto.gallery.

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    May 2012
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Archive for May, 2012

Troubleshooting App Engine-connected Android projects with c2dm

Posted by David Chandler on May 18, 2012

Google Plugin for Eclipse has a wizard to create an Android project with App Engine back end including client push (c2dm). The official tutorial is quite good, but after spending the better part of a day trying to get the Cloud Tasks sample up and running again, I thought it might be useful to post a few tips.

General Tips

  • Sign up for c2dm first. Remember the package name and use it when running the Eclipse wizard! The package name is required, and once you choose the package name on c2dm sign-up, it is nowhere visible later. Be patient–it may take an hour or even a day to activate your account.
  • Sign in to Eclipse with the c2dm account name you’ll use (see lower left corner–if not visible, you need Google Plugin for Eclipse). It’s easy to forget this, but Debug As | Local App Engine Connected Project requires you to be signed in.

Run on a Phone With the GAE Dev Server

In this scenario, the phone and dev server must be on the same network! Easiest way is to connect to the same wi-fi router. USB cable does nothing. Be aware that most public wi-fi routers don’t allow devices to contact each other, so it will probably work best at home or on your company’s guest wi-fi network.

  • Ensure that phone and dev server are on the same wi-fi network. Disconnect both from any VPNs.
  • Add -bindAddress to your Web project’s Run Configuration | Program Arguments. This will start the server listening on all addresses, not just the default localhost (which the phone can’t see).
  • When you choose Debug As | Local App Engine Connected Android Application, GPE hardcodes your machine’s IP address in assets/debugging_prefs.properties. This is where the Android app looks up the address of the server.
  • You can launch/debug the Android app and the Web app independently; however, if your server IP address changes, you must again Debug As | Local App Engine Connected Android Application in order to update the IP address in assets/debugging_prefs.properties.
  • In case you wondered, the Android and Web projects are associated in a file in the Android project. You can find it in .settings/com.google.gdt.eclipse.mobile.android.prefs. To associate a different App Engine project with an Android project, simply edit this file and refresh the project.
  • If you’re using the GWT dev mode browser plugin, you can still connect to If you connect to the address shown in Development Mode tab (your machine’s network IP address), you may need to allow the address in the dev mode browser plugin. Click the GWT icon in the address bar to do this.
  • Make sure you log in to the Web app as the c2dm user, not the default test@example.com.

Run on a Phone Against the Production App

In the production scenario, you’re using real c2dm so the phone doesn’t have to be on wi-fi at all.

  • Edit Setup.java and change APP_NAME and SENDER_ID to match your GAE app id and c2dm account.
  • Change app id in appengine-web.xml to match your GAE app.
  • Deploy to App Engine with your c2dm account.
  • Force sign in to GAE app by going to [prod_url]/tasks/. This triggers the security constraint in web.xml to get logged in to GAE. After logging in, you’ll get an error page, but that’s OK. Then go to [prod_url]/ and Say Hello to App Engine. If logged in, you should see a success message.
  • If you’ve previously connected an account on a phone to this production app, go to GAE datastore viewer and delete all records.
  • In Eclipse, Debug as | Remote App Engine Connected Android project
  • On the phone, you’ll be prompted to connect an account. Use your c2dm account. If you have previously connected a different account, go to Menu | Accounts | Disconnect in the app and reconnect.

The CloudTasks project still has a few issues. Feel free to log them in the tracker.

Posted in Android, AppEngine, Google Web Toolkit | 7 Comments »

Show soft keyboard automatically when EditText receives focus

Posted by David Chandler on May 2, 2012

I’ve been unpleasantly surprised at how difficult it is to find info on showing or hiding the Android soft keyboard, so I’m putting a few code snippets out here for posterity.


I have a DialogFragment with an EditText. When the dialog is shown, I want to immediately focus the EditText and show the keyboard.

Solution 1 (recommended)

Set the dialog Window’s soft input method.

public class EditNameDialog extends DialogFragment {

	private EditText editText;

	public EditNameDialog() {
		// Empty constructor required for DialogFragment

	public View onCreateView(LayoutInflater inflater, ViewGroup container,
			Bundle savedInstanceState) {
		View view = inflater.inflate(R.layout.fragment_edit_name, container);
		editText = (EditText) view.findViewById(R.id.txt_yourName);

		// Request focus and show soft keyboard automatically

		return view;

As an alternative to editText.requestFocus(), you can use the <requestFocus /> tag in the fragment’s XML layout:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" >

        android:text="What is your name?" />

        android:ems="10" >
		<requestFocus />


Setting the Window’s soft input method is definitely the easiest way to show the keyboard. However, in some circumstances, you may need to “force” it open or shut by invoking the InputMethodManager directly.

Solution 2

Invoke the InputMethodManager service.

This approach is more complicated because the input method manager ignores keyboard requests unless the EditText and the Window it’s in both have focus. So upon entering an Activity / Dialog, you need to wait until focus has settled down before you request the keyboard. You can do this by calling the InputMethodManager service in an OnFocusChangeListener, but Views can get focus before the Window itself does, so you have to wait for Window focus. There is no way that I can find to add an OnFocusChangeListener on the Window object itself, but listening for View focus and posting a Runnable seems to work:

		editText.setOnFocusChangeListener(new OnFocusChangeListener() {
			public void onFocusChange(View v, boolean hasFocus) {
				editText.post(new Runnable() {
					public void run() {
						InputMethodManager imm = (InputMethodManager) getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
						imm.showSoftInput(editText, InputMethodManager.SHOW_IMPLICIT);

This solution is not recommended because it may be buggy, but illustrates using post() to wait for the UI to settle, which may be useful in other circumstances. Note that this solution won’t work with the requestFocus tag in the layout XML because in that case, the EditText receives focus before the OnFocusChangeListener has been registered. Therefore, in the example above, we programmatically request focus after adding the listener.

Bad solutions

You can set the attribute android:windowSoftInputMode=”stateVisible” for your activity in AndroidManifest.xml. However, in the case of a DialogFragment, that will show the keyboard in the Activity’s window, which is behind the Window associated with the Dialog in the DialogFragment.

In order to get around possible Window / View focus bugs, you can use postDelayed() with a number of milliseconds to post a Runnable; however, hard-coded delays are never recommended because they may introduce unpredictable behavior under different conditions / different devices.


Ordinarily, the soft keyboard default behavior should be sufficient; however, when you programmatically focus on an EditText, you can set the Window’s soft input method to show the keyboard.

Posted in Android | 18 Comments »

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