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POAndroid Activity lifecycle causing View refresh problems
 

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  1. POAndroid Activity lifecycle causing View refresh problems
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    <p>I've got a problem in a big project. I'll try to boil it down to what (I hope) are the important points. I have an app that consists of several <code>Activity</code>s, one of which is the main navigation point that the others are launched from. </p> <p>Once the main <code>Activity</code> gets destroyed and recreated (by navigating to another <code>Activity</code> and back), view updates don't seem to work. Specifically, I have a <code>Button</code> and several <code>TextView</code>s. After the <code>Activity</code> is recreated, I can't change their text. I've tried changing the <code>Activity</code> background color, and that doesn't work, either.</p> <p>My first thought was that I missed an important data member during the save/restore process. However, I've looked at that quite a bit, and I think that's not the problem. Also, I've tried not loading the saved data and starting fresh and it still doesn't update the views.</p> <p>Next, I considered that I might not be updating on the UI thread. I'm certain that causes an exception, but to be sure, I posted refreshes to <code>Handler</code>. Still no dice.</p> <p>I can, however, get limited UI changes visible if I wire them to an <code>onClick()</code>. What works and what doesn't in that case raises other questions (some of the data is corrupted), so right now that's where I'm concentrating my investigation. I'll provide an update once I get more of that mapped out. </p> <p>What else should I be looking at?</p> <p>UPDATE: Adding some snippets:</p> <p>From <code>onCreate()</code>:</p> <pre><code>if (savedInstanceState != null) { Log.v(Calculations.log, "Restarting with saved instance state"); Serializable ser = savedInstanceState.getSerializable("infusion"); if ((ser != null) &amp;&amp; (ser instanceof Infusion)) { mInfusion = (Infusion) ser; } mBeganEditing = savedInstanceState.getBoolean("editing", mInfusion != null); Log.v(Calculations.log, this.toString()); } </code></pre> <p>and its matching <code>onSaveInstanceState()</code>:</p> <pre><code>@Override protected void onSaveInstanceState(Bundle outState) { Log.v(Calculations.log, "StageInfusion::onSaveInstanceState()"); Log.v(Calculations.log, this.toString()); outState.putSerializable("infusion", mInfusion); outState.putBoolean("editing", mBeganEditing); outState.putBoolean("resume", true); ServerManager.stopListening(); super.onSaveInstanceState(outState); } </code></pre> <p>I expect that there are other members that should be saved, but they're of minor consequence.</p>
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    1. PTQuestion
    1. USTodd Sjolander
    1. USTodd Sjolander
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    1. COFrom what you've said I'd guess that you're holding on to old view objects that are no longer valid, but it's hard to say for sure without you posting some code (especially the save/restore code that you talk about).
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      1. POAndroid Activity lifecycle causing View refresh problems
      1. USkabuko
    2. COare you sure your activity gets destroyed? unless you call finish, when you create a new activity, the old one is still there, just stopped.
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      1. POAndroid Activity lifecycle causing View refresh problems
      1. UStoadzky
    3. COThat's something I briefly considered. Maybe it merits more thought. In my `onCreate()`, I use the typical `runView = (RunView) findViewById(R.id.runView);' statements to set the `View` objects (stored as object members, not method-local). As expected, `onCreate` does get called upon re-creation of the Activity, so I'd expect all of those `View` objects to be valid. At any rate, I'll update with some code.
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      1. POAndroid Activity lifecycle causing View refresh problems
      1. USTodd Sjolander
 

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