我的MainActivity正在加载不同的片段。此外，可以从MainActivity打开Settings-Activity。
如果用户只在片段之间切换，一切都很好。
打开Settings-Activity并返回MainActivity时，onResume和onPause会被调用两次。如果用户打开“设置 - 活动”并再次返回到MainActivity，则会在onResume和onPause上调用三次。每次用户打开“设置 - 活动”并返回“MainActivity”时，此值都会增加。
MainActivity
public class MainActivity extends AppCompatActivity implements MyFragment.OnListFragmentInteractionListener, AsyncResponse {
private FragmentA fragmentA = new FragmentA();
private DatabaseHandler databaseHandler = new DatabaseHandler(this);
private NavigationView navigationView;
private DrawerLayout drawer;
private Toolbar toolbar;
// index to identify current nav menu item
private static int navItemIndex = 0;
public static String CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
// toolbar titles respected to selected nav menu item
private String[] activityTitles;
// flag to load home fragment when user presses back key
private Handler mHandler;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
fragmentA.setDatabaseHandler(this.databaseHandler);
// Init UI
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
mHandler = new Handler();
drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
navigationView = (NavigationView) findViewById(R.id.nav_view);
fabSendButton = (FloatingActionButton) findViewById(R.id.fab);
// Navigation view header
navHeader = navigationView.getHeaderView(0);
// load toolbar titles from string resources
activityTitles = getResources().getStringArray(R.array.sliding_menu_item_activity_titles);
// initializing navigation menu
setUpNavigationView();
if (savedInstanceState == null) {
navItemIndex = 0;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
loadHomeFragment();
}
}
/***
* Returns respected fragment that user
* selected from navigation menu
*/
private void loadHomeFragment() {
// set toolbar title
setToolbarTitle();
// if user select the current navigation menu again, don't do anything
// just close the navigation drawer
if (getSupportFragmentManager().findFragmentByTag(CURRENT_TAG) != null) {
drawer.closeDrawers();
return;
}
// Sometimes, when fragment has huge data, screen seems hanging
// when switching between navigation menus
// So using runnable, the fragment is loaded with cross fade effect
// This effect can be seen in GMail app
Runnable mPendingRunnable = new Runnable() {
@Override
public void run() {
// update the activity_main_header_with_item content by replacing fragments
Fragment fragment = getFragment();
FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
fragmentTransaction.setCustomAnimations(android.R.anim.fade_in, android.R.anim.fade_out);
fragmentTransaction.replace(R.id.frame, fragment, CURRENT_TAG);
fragmentTransaction.commit();
}
};
// If mPendingRunnable is not null, then add to the message queue
if (mPendingRunnable != null) {
mHandler.post(mPendingRunnable);
}
//Closing drawer on item click
drawer.closeDrawers();
// refresh toolbar menu
invalidateOptionsMenu();
}
private Fragment getFragment() {
switch (navItemIndex) {
case 0:
return this.fragmentA;
case 1:
Fragment B fragmentB = new FragmentB();
fragmentB.setDatabaseHandler(this.databaseHandler);
return fragmentB;
default:
return this.fragmentA;
}
}
private void setToolbarTitle() {
getSupportActionBar().setTitle(activityTitles[navItemIndex]);
}
private void setUpNavigationView() {
//Setting Navigation View Item Selected Listener to handle the item click of the navigation menu
navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
// This method will trigger on item Click of navigation menu
@Override
public boolean onNavigationItemSelected(MenuItem menuItem) {
//Check to see which item was being clicked and perform appropriate action
switch (menuItem.getItemId()) {
//Replacing the activity_main_header_with_item content with ContentFragment Which is our Inbox View;
case R.id.nav_A:
navItemIndex = 0;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_A;
break;
case R.id.nav_B:
navItemIndex = 1;
CURRENT_TAG = MyConstants.TAG_FRAGMENT_B;
break;
default:
navItemIndex = 0;
}
loadHomeFragment();
return true;
}
});
ActionBarDrawerToggle actionBarDrawerToggle = new ActionBarDrawerToggle(this, drawer, toolbar, R.string.openDrawer, R.string.closeDrawer) {
@Override
public void onDrawerClosed(View drawerView) {
// Code here will be triggered once the drawer closes as we dont want anything to happen so we leave this blank
super.onDrawerClosed(drawerView);
}
@Override
public void onDrawerOpened(View drawerView) {
// Code here will be triggered once the drawer open as we dont want anything to happen so we leave this blank
super.onDrawerOpened(drawerView);
}
};
//Setting the actionbarToggle to drawer layout
drawer.setDrawerListener(actionBarDrawerToggle);
//calling sync state is necessary or else your hamburger icon wont show up
actionBarDrawerToggle.syncState();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main_header_with_item, menu);
return true;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main_header_with_item, menu);
// Disable Player Icon in case no player is found on device
Intent intent = Intent.makeMainSelectorActivity(Intent.ACTION_MAIN, ScrobblOrDroidConstants.MUSIC_APP);
List<ResolveInfo> activities = getPackageManager().queryIntentActivities(intent, 0);
if(activities == null || activities.size() <= 0) {
MenuItem player = menu.findItem(R.id.player);
if(player != null){
player.setVisible(false);
}
}
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.player) {
Timber.i( "Added onClick listener to ImageView ivPlayer.");
Intent intent = Intent.makeMainSelectorActivity(Intent.ACTION_MAIN, ScrobblOrDroidConstants.MUSIC_APP);
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
return true;
} else if (id == R.id.settings) {
// launch settings activity
startActivity(new Intent(MainActivity.this, SettingsActivity.class));
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onResume() {
Timber.i("MainActivity.onResume-called.");
activityVisible = true;
updateHomeFragment();
callLongUserOperation();
super.onResume();
}
@Override
public void onPause() {
Timber.i("MainActivity.onPause-called.");
activityVisible = false;
super.onPause();
}
}
public void updateHomeFragment() {
if (CURRENT_TAG == MyConstants.TAG_HOME) {
Timber.i( "updating HomeFragment");
fragmentA.swap();
}
}
SettingsActivity
public class SettingsActivity extends AppCompatPreferenceActivity implements SharedPreferences.OnSharedPreferenceChangeListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setupActionBar();
getFragmentManager().beginTransaction().replace(android.R.id.content, new MainPreferenceFragment()).commit();
}
private void setupActionBar() {
ViewGroup rootView = (ViewGroup)findViewById(R.id.action_bar_root);
View view = getLayoutInflater().inflate(R.layout.pref_toolbar, rootView, false);
rootView.addView(view, 0);
Toolbar toolbar = (Toolbar)findViewById(R.id.pref_toolbar);
setSupportActionBar(toolbar);
ActionBar actionBar = getSupportActionBar();
if (actionBar != null) {
// Show the Up button in the action bar.
actionBar.setDisplayHomeAsUpEnabled(true);
}
}
public static class MainPreferenceFragment extends PreferenceFragment {
@Override
public void onCreate(final Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addPreferencesFromResource(R.xml.pref_main);
// gallery EditText change listener
bindPreferenceSummaryToValue(findPreference(MyConstants.RECENTLY_SCROBBLED_KEY));
bindPreferenceSummaryToValue(findPreference(MyConstants.SCROBBLE_DURATION_KEY));
// feedback preference click listener
Preference myPref = findPreference("key_send_feedback");
myPref.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
public boolean onPreferenceClick(Preference preference) {
sendFeedback(getActivity());
return true;
}
});
// rating preference click listener
Preference myPrefRate = findPreference("key_send_rate");
myPrefRate.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
public boolean onPreferenceClick(Preference preference) {
sendRating(getActivity());
return true;
}
});
}
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
if (item.getItemId() == android.R.id.home) {
onBackPressed();
}
return super.onOptionsItemSelected(item);
}
private static void bindPreferenceSummaryToValue(Preference preference) {
preference.setOnPreferenceChangeListener(sBindPreferenceSummaryToValueListener);
sBindPreferenceSummaryToValueListener.onPreferenceChange(preference,
PreferenceManager.getDefaultSharedPreferences(preference.getContext()).getString(preference.getKey(), ""));
}
/**
* A preference value change listener that updates the preference's summary
* to reflect its new value.
*/
private static Preference.OnPreferenceChangeListener sBindPreferenceSummaryToValueListener = new Preference.OnPreferenceChangeListener() {
@Override
public boolean onPreferenceChange(Preference preference, Object newValue) {
String stringValue = newValue.toString();
if(preference.getKey().equalsIgnoreCase(MyConstants.RECENTLY_SCROBBLED_KEY)){
preference.setSummary(stringValue + " " + preference.getContext().getResources().getString(R.string.pref_recently_scrobbled_summary));
}
if(preference.getKey().equalsIgnoreCase(MyConstants.SCROBBLE_DURATION_KEY)){
preference.setSummary(preference.getContext().getResources().getString(R.string.pref_scrobble_percentage_summary, stringValue));
}
return true;
}
};
/**
* Email client intent to send support mail
* Appends the necessary device information to email body
* useful when providing support
*/
public static void sendFeedback(Context context) {
String body = null;
try {
body = context.getPackageManager().getPackageInfo(context.getPackageName(), 0).versionName;
body = "\n\n-----------------------------\nPlease don't remove this information\n Device OS: Android \n Device OS version: " +
Build.VERSION.RELEASE + "\n App Version: " + body + "\n Device Brand: " + Build.BRAND +
"\n Device Model: " + Build.MODEL + "\n Device Manufacturer: " + Build.MANUFACTURER;
} catch (PackageManager.NameNotFoundException e) {
}
Intent intent = new Intent(Intent.ACTION_SEND);
intent.setType("message/rfc822");
intent.putExtra(Intent.EXTRA_EMAIL, new String[]{MyConstants.E_MAIL_ADDRESS});
intent.putExtra(Intent.EXTRA_SUBJECT, "Feedback for " + context.getResources().getString(R.string.app_name));
intent.putExtra(Intent.EXTRA_TEXT, body);
context.startActivity(Intent.createChooser(intent, context.getString(R.string.pref_choose_email_client)));
}
public static void sendRating(Context context) {
Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(MyConstants.PLAY_STORE_URL));
context.startActivity(i);;
}
@Override
public void onResume() {
super.onResume();
PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).registerOnSharedPreferenceChangeListener(this);
}
@Override
public void onPause() {
PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).registerOnSharedPreferenceChangeListener(this);
super.onPause();
}
@Override
public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
if(key.equalsIgnoreCase(MyConstants.NOTIFICATION_ENABLED_KEY)){
EventBus.getDefault().post(new NotificationEvent());
Timber.i( "NotificationEvent Posted");
}
}
}
AppCompatPreferenceActivity
public class AppCompatPreferenceActivity extends PreferenceActivity {
private AppCompatDelegate mDelegate;
@Override
protected void onCreate(Bundle savedInstanceState) {
getDelegate().installViewFactory();
getDelegate().onCreate(savedInstanceState);
super.onCreate(savedInstanceState);
}
@Override
protected void onPostCreate(Bundle savedInstanceState) {
super.onPostCreate(savedInstanceState);
getDelegate().onPostCreate(savedInstanceState);
}
public ActionBar getSupportActionBar() {
return getDelegate().getSupportActionBar();
}
public void setSupportActionBar(@Nullable Toolbar toolbar) {
getDelegate().setSupportActionBar(toolbar);
}
@Override
public MenuInflater getMenuInflater() {
return getDelegate().getMenuInflater();
}
@Override
public void setContentView(@LayoutRes int layoutResID) {
getDelegate().setContentView(layoutResID);
}
@Override
public void setContentView(View view) {
getDelegate().setContentView(view);
}
@Override
public void setContentView(View view, ViewGroup.LayoutParams params) {
getDelegate().setContentView(view, params);
}
@Override
public void addContentView(View view, ViewGroup.LayoutParams params) {
getDelegate().addContentView(view, params);
}
@Override
protected void onPostResume() {
super.onPostResume();
getDelegate().onPostResume();
}
@Override
protected void onTitleChanged(CharSequence title, int color) {
super.onTitleChanged(title, color);
getDelegate().setTitle(title);
}
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
getDelegate().onConfigurationChanged(newConfig);
}
@Override
protected void onStop() {
super.onStop();
getDelegate().onStop();
}
@Override
protected void onDestroy() {
super.onDestroy();
getDelegate().onDestroy();
}
public void invalidateOptionsMenu() {
getDelegate().invalidateOptionsMenu();
}
private AppCompatDelegate getDelegate() {
if (mDelegate == null) {
mDelegate = AppCompatDelegate.create(this, null);
}
return mDelegate;
}
}
的AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.ordroid.My"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk
android:minSdkVersion="15"
android:targetSdkVersion="25" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme">
<activity
android:name=".ui.activity.MainActivity"
android:label="@string/app_name"
android:screenOrientation="portrait">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name=".ui.activity.LoginActivity"
android:excludeFromRecents="true"
android:label="@string/app_name"
android:screenOrientation="portrait"></activity>
<activity
android:name=".ui.activity.SettingsActivity"
android:label="@string/settings">
<!-- Parent activity meta-data to support 4.0 and lower -->
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value=".ui.activity.MainActivity" />
</activity>
<!-- start service on device boot complete -->
<receiver
android:name=".util.receiver.MyBroadcastReceiver"
android:enabled="true"
android:exported="true"
android:label="StartMyServiceAtBootReceiver">
<intent-filter>
<action android:name="com.android.music.metachanged" />
<action android:name="com.android.music.playstatechanged" />
<!-- <action android:name="android.intent.action._BOOT_COMPLETED" /> -->
</intent-filter>
</receiver>
<receiver android:name=".util.receiver.MyInternetConnectionBroadcastReceiver">
<intent-filter>
<action android:name="android.net.conn.CONNECTIVITY_CHANGE" />
</intent-filter>
</receiver>
</application>
</manifest>
如何避免这些多次通话？
答案 0 :(得分：1)
似乎这是Android SDK Build Tool中的一个错误。更新后，它可以充当魅力！
答案 1 :(得分：0)
我遇到了同样的问题，其中我的一个活动的onResume（）被调用三次。
我通过将相应活动的onCreate（）中的布尔值设置为false来修复它。例如：
boolean onResumeCalled = false
每次创建活动时，我都会将onResumeCalled保持为false。
在onResume（）中，我设置了一个检查
if(!onResumeCalled)
在onResume（）的开头。
现在，创建活动时，onResumeCalled为false。然后，一旦onResume（）内部的方法被调用，我将onResumeCalled的值更改为true，以便第二次调用onResume（）时，onResume（）内的方法将不会被访问，因为onResumeCalled的值现在是真。
答案 2 :(得分：0)
我发现here在Android上有这种行为的某些原因。对我来说，这就是原因。
onPause-onResume-onPause-onResume只会在应用程序每次运行时发生 安装后首次启动。您可以简单地调用此 通过更改代码并重新运行（包括 从您的IDE重新编译）。
无论您是否使用AppCompat库。