mirror of https://github.com/moparisthebest/k-9
112 lines
3.2 KiB
Java
112 lines
3.2 KiB
Java
package com.fsck.k9.activity.misc;
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import android.app.Activity;
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import android.app.ProgressDialog;
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import android.content.Context;
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import android.os.AsyncTask;
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/**
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* Extends {@link AsyncTask} with methods to attach and detach an {@link Activity}.
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*
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* <p>
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* This is necessary to properly handle configuration changes that will restart an activity.
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* </p><p>
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* <strong>Note:</strong>
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* Implementing classes need to make sure they have no reference to the {@code Activity} instance
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* that created the instance of that class. So if it's implemented as inner class, it needs to be
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* {@code static}.
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* </p>
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*
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* @param <Params>
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* see {@link AsyncTask}
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* @param <Progress>
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* see {@link AsyncTask}
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* @param <Result>
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* see {@link AsyncTask}
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*
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* @see #restore(Activity)
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* @see #retain()
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*/
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public abstract class ExtendedAsyncTask<Params, Progress, Result>
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extends AsyncTask<Params, Progress, Result> implements NonConfigurationInstance {
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protected Activity mActivity;
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protected Context mContext;
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protected ProgressDialog mProgressDialog;
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protected ExtendedAsyncTask(Activity activity) {
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mActivity = activity;
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mContext = activity.getApplicationContext();
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}
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/**
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* Connect this {@link AsyncTask} to a new {@link Activity} instance after the activity
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* was restarted due to a configuration change.
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*
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* <p>
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* This also creates a new progress dialog that is bound to the new activity.
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* </p>
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*
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* @param activity
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* The new {@code Activity} instance. Never {@code null}.
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*/
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@Override
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public void restore(Activity activity) {
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mActivity = activity;
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showProgressDialog();
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}
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/**
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* Detach this {@link AsyncTask} from the {@link Activity} it was bound to.
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*
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* <p>
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* This needs to be called when the current activity is being destroyed during an activity
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* restart due to a configuration change.<br/>
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* We also have to destroy the progress dialog because it's bound to the activity that's
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* being destroyed.
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* </p>
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*
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* @return {@code true} if this instance should be retained; {@code false} otherwise.
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*
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* @see Activity#onRetainNonConfigurationInstance()
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*/
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@Override
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public boolean retain() {
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boolean retain = false;
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if (mProgressDialog != null) {
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removeProgressDialog();
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retain = true;
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}
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mActivity = null;
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return retain;
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}
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/**
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* Creates a {@link ProgressDialog} that is shown while the background thread is running.
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*
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* <p>
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* This needs to store a {@code ProgressDialog} instance in {@link #mProgressDialog} or
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* override {@link #removeProgressDialog()}.
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* </p>
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*/
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protected abstract void showProgressDialog();
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protected void removeProgressDialog() {
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mProgressDialog.dismiss();
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mProgressDialog = null;
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}
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/**
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* This default implementation only creates a progress dialog.
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*
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* <p>
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* <strong>Important:</strong>
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* Be sure to call {@link #removeProgressDialog()} in {@link AsyncTask#onPostExecute(Object)}.
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* </p>
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*/
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@Override
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protected void onPreExecute() {
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showProgressDialog();
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}
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}
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