为什么我的 Activity 在添加片段 (#2) 时被销毁？
Why does my Activity get destroyed upon adding a fragment (#2)?
我想说明一下，这个问题看起来与 非常相似，但我问的并不是完全相同的问题。
在我之前的问题中，我得到了一个 RuntimeException/IllegalStateException，它告诉我我的 Activity 在添加新片段时被销毁了。
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp
/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException:
Activity has been destroyed
在那种情况下，事实证明这与我以无效方式创建 MainActivity 的新实例有关：
MainActivity ma = new MainActivity();
（PSA：不要执行上述操作，而是使用 MainActivity ma = (MainActivity) getActivity();。）
我现在已经在我的整个项目中更正了这个问题，并且得到了几乎完全相同的错误。让我说清楚：我（认为我）知道原来的错误已修复，因为我在这两个 RE 之间得到了一个不同的错误，我能够自己修复它。
重申我的胡言乱语：得到第一个 RE，用我的问题的答案修复它，得到一个不同的错误，自己修复，得到 几乎 完全相同的 RE .
我搜索了我的整个项目，看看是否有与我之前犯的错误类似的东西，但我找不到任何东西，所以我来了。所以基本上，我在上一个问题上得到的答案暂时解决了我的问题。但是，这个答案对我遇到的这个新错误没有帮助，这就是我问这个问题的原因。
TL;DR: Q1 的回答首先解决了我的问题（这使它成为一个有效的答案），但它 不是 解决我现在遇到的问题，几乎 是一样的。
实际问题
所以，现在我们已经解决了这个问题，让我们继续解决我的问题。所以，我得到一个 RuntimeException/IllegalStateExcetion:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}:
java.lang.IllegalStateException: Activity has been destroyed
(PS。这只是一个 RE，因为我让我的应用程序在启动时导航到 GeneralSettings 片段，以便于调试。)
我已经阅读过此类错误，但我找不到任何适用于我的项目的错误。
那么，是什么导致了这个 RuntimeException/IllegalStateException？
完整日志
04-05 14:17:53.140 23411-23411/? I/art: Not late-enabling -Xcheck:jni (already on)
04-05 14:17:53.190 23411-23411/com.example.tim.timapp W/System: ClassLoader referenced unknown path: /data/app/com.example.tim.timapp-1/lib/x86_64
04-05 14:17:53.210 23411-23411/com.example.tim.timapp D/TEST DBHandler: sInstance == null
04-05 14:17:53.370 23411-23411/com.example.tim.timapp D/AndroidRuntime: Shutting down VM
04-05 14:17:53.370 23411-23411/com.example.tim.timapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tim.timapp, PID: 23411
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException: Activity has been destroyed
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: Activity has been destroyed
at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1433)
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:687)
at android.app.BackStackRecord.commit(BackStackRecord.java:663)
at com.example.tim.timapp.MainActivity.DrawVariableFragments(MainActivity.java:276)
at com.example.fragments.Settings.GeneralSettingsFragment.onCreateView(GeneralSettingsFragment.java:58)
at android.app.Fragment.performCreateView(Fragment.java:2220)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:973)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
at android.app.BackStackRecord.run(BackStackRecord.java:793)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1535)
at android.app.FragmentController.execPendingActions(FragmentController.java:325)
at android.app.Activity.performStart(Activity.java:6252)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
主要内容Activity（片段）
package com.example.tim.timapp;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private static boolean isMainShown = false;
private static boolean isSettingsShown = false;
private static boolean doSavePopup = false;
private static String backTitle = "";
private String tag = "TEST MA";
DBHandler dbHandler;
Menu menu;
public void DrawVariableFragments(String base,String token){
// FragmentManager fm = getFragmentManager();
ArrayList<String> Data;
dbHandler = DBHandler.getInstance(this);
int AmountOfEntries;
int SettingsContainer;
String SettingsTag;
Fragment SettingsVariableFragment;
Fragment SettingsEmptyFragment;
if (base.equalsIgnoreCase("StuffManager")) {
Data = new ArrayList<String>() {{add("StuffManager"); add("name"); add("tag"); }};
SettingsContainer = R.id.FragmentContainer2;
SettingsTag = getString(R.string.navdrawer_stuffmanager);
SettingsVariableFragment = new StuffManagerVariableFragment();
SettingsEmptyFragment = new StuffManagerEmptyFragment();
} else if (base.equalsIgnoreCase("GeneralSettings")) {
Data = new ArrayList<String>() {{add("GeneralSettings"); add("name"); add("ip"); add("port"); add("username"); add("pass"); }};
SettingsContainer = R.id.FragmentContainerGeneralSettings;
SettingsTag = getString(R.string.navdrawer_generalsettings);
SettingsVariableFragment = new GeneralSettingsVariableFragment();
SettingsEmptyFragment = new GeneralSettingsEmptyFragment();
} else {
Log.e(tag, "String Base not recognised");
return;
}
AmountOfEntries = dbHandler.returnArray(base, Data.get(1)).size();
FragmentManager fm = getFragmentManager().findFragmentByTag(SettingsTag).getChildFragmentManager();
if ((dbHandler.returnArray(base, Data.get(1))).size() == 0 ) {
// Log.d(tag, "SettingsContainer1: " + String.valueOf(SettingsContainer) + "; SettingsEmtpyFragment1: " + SettingsEmptyFragment + "; Base1: " + base);
fm.beginTransaction().add(SettingsContainer, SettingsEmptyFragment, (base + "EmptyFragment")).commit();
fm.executePendingTransactions();
return;
}
if (AmountOfEntries > 0) {
String EmptyFragName = (base + "EmptyFragment");
if ((fm.findFragmentByTag(EmptyFragName)) != null) {
fm.beginTransaction().remove(fm.findFragmentByTag(EmptyFragName)).commit();
fm.executePendingTransactions();
}
for (int i = 0; i < AmountOfEntries; i++) {
ArrayList<String> fragmentData = new ArrayList<>();
for (int k=1; k < Data.size(); k++) {
int j=k-1;
fragmentData.set(j, (dbHandler.returnArray(base, Data.get(k)).get(j)));
}
if (token.equalsIgnoreCase("edit")) {
LinearLayout linearLayout = (LinearLayout) findViewById(SettingsContainer);
linearLayout.removeAllViews();
DrawVariableFragments(base ,"draw");
} else if (token.equalsIgnoreCase("add")) {
if (fm.findFragmentByTag(fragmentData.get(i)) == null) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
} else if (token.equalsIgnoreCase("draw")) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
}
} else {
Log.d("TEST", "WTF, nameArray.size != 0 && !> 0");
}
}
}
GeneralSettingsFragment（代码段）
package com.example.fragments.Settings;
public class GeneralSettingsFragment extends Fragment {
MainActivity ma;
DBHandler dbHandler;
private static Menu optionsMenu;
public static boolean hideDeleteAllButton = false;
LinearLayout linearLayout;
View rootView;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_generalsettings, container, false);
ma = (MainActivity) getActivity();
linearLayout = (LinearLayout) rootView.findViewById(R.id.FragmentContainerGeneralSettings);
if (linearLayout == null) {
Log.e("GMF", "Layout is null");
} else if (linearLayout.getChildCount() == 0) {
GeneralSettingsInitialInputDialog GSIID = new GeneralSettingsInitialInputDialog();
GSIID.show(getFragmentManager(), "dialog");
hideDeleteAllButton = true;
} else {
hideDeleteAllButton = false;
}
ma.DrawVariableFragments("GeneralSettings", "draw");
return rootView;
}
}
您仍在以不受支持的方式做事。在 MainActivity.DrawVariableFragments() 中，您正在创建一个新的 GeneralSettingsVariableFragment()，然后对其调用 getChildFragmentManager() 并尝试提交片段。
GeneralSettingsFragment 尚未附加到 Activity，因此它没有主机。这会引发您在尝试提交 FragmentTransaction.
时看到的 IllegalStateException("Activity has been destroyed") 异常
不清楚为什么要创建一个新的 GeneralSettingsVariableFragment，而您已经在其中的一个新实例中。
要正确查找现有片段，请使用 getFragmentManager().findFragmentByTag(...) 或 getFragmentManager().findFragmentById(...)。
我想说明一下，这个问题看起来与
在我之前的问题中，我得到了一个 RuntimeException/IllegalStateException，它告诉我我的 Activity 在添加新片段时被销毁了。
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp
/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException:
Activity has been destroyed
在那种情况下，事实证明这与我以无效方式创建 MainActivity 的新实例有关：
MainActivity ma = new MainActivity();
（PSA：不要执行上述操作，而是使用 MainActivity ma = (MainActivity) getActivity();。）
我现在已经在我的整个项目中更正了这个问题，并且得到了几乎完全相同的错误。让我说清楚：我（认为我）知道原来的错误已修复，因为我在这两个 RE 之间得到了一个不同的错误，我能够自己修复它。
重申我的胡言乱语：得到第一个 RE，用我的问题的答案修复它，得到一个不同的错误，自己修复，得到 几乎 完全相同的 RE .
我搜索了我的整个项目，看看是否有与我之前犯的错误类似的东西，但我找不到任何东西，所以我来了。所以基本上，我在上一个问题上得到的答案暂时解决了我的问题。但是，这个答案对我遇到的这个新错误没有帮助，这就是我问这个问题的原因。
TL;DR: Q1 的回答首先解决了我的问题（这使它成为一个有效的答案），但它 不是 解决我现在遇到的问题，几乎 是一样的。
实际问题
所以，现在我们已经解决了这个问题，让我们继续解决我的问题。所以，我得到一个 RuntimeException/IllegalStateExcetion:
java.lang.RuntimeException: Unable to start activity
ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}:
java.lang.IllegalStateException: Activity has been destroyed
(PS。这只是一个 RE，因为我让我的应用程序在启动时导航到 GeneralSettings 片段，以便于调试。)
我已经阅读过此类错误，但我找不到任何适用于我的项目的错误。
那么，是什么导致了这个 RuntimeException/IllegalStateException？
完整日志
04-05 14:17:53.140 23411-23411/? I/art: Not late-enabling -Xcheck:jni (already on)
04-05 14:17:53.190 23411-23411/com.example.tim.timapp W/System: ClassLoader referenced unknown path: /data/app/com.example.tim.timapp-1/lib/x86_64
04-05 14:17:53.210 23411-23411/com.example.tim.timapp D/TEST DBHandler: sInstance == null
04-05 14:17:53.370 23411-23411/com.example.tim.timapp D/AndroidRuntime: Shutting down VM
04-05 14:17:53.370 23411-23411/com.example.tim.timapp E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.tim.timapp, PID: 23411
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tim.timapp/com.example.tim.timapp.MainActivity}: java.lang.IllegalStateException: Activity has been destroyed
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.IllegalStateException: Activity has been destroyed
at android.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1433)
at android.app.BackStackRecord.commitInternal(BackStackRecord.java:687)
at android.app.BackStackRecord.commit(BackStackRecord.java:663)
at com.example.tim.timapp.MainActivity.DrawVariableFragments(MainActivity.java:276)
at com.example.fragments.Settings.GeneralSettingsFragment.onCreateView(GeneralSettingsFragment.java:58)
at android.app.Fragment.performCreateView(Fragment.java:2220)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:973)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1148)
at android.app.BackStackRecord.run(BackStackRecord.java:793)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1535)
at android.app.FragmentController.execPendingActions(FragmentController.java:325)
at android.app.Activity.performStart(Activity.java:6252)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
主要内容Activity（片段）
package com.example.tim.timapp;
public class MainActivity extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
private static boolean isMainShown = false;
private static boolean isSettingsShown = false;
private static boolean doSavePopup = false;
private static String backTitle = "";
private String tag = "TEST MA";
DBHandler dbHandler;
Menu menu;
public void DrawVariableFragments(String base,String token){
// FragmentManager fm = getFragmentManager();
ArrayList<String> Data;
dbHandler = DBHandler.getInstance(this);
int AmountOfEntries;
int SettingsContainer;
String SettingsTag;
Fragment SettingsVariableFragment;
Fragment SettingsEmptyFragment;
if (base.equalsIgnoreCase("StuffManager")) {
Data = new ArrayList<String>() {{add("StuffManager"); add("name"); add("tag"); }};
SettingsContainer = R.id.FragmentContainer2;
SettingsTag = getString(R.string.navdrawer_stuffmanager);
SettingsVariableFragment = new StuffManagerVariableFragment();
SettingsEmptyFragment = new StuffManagerEmptyFragment();
} else if (base.equalsIgnoreCase("GeneralSettings")) {
Data = new ArrayList<String>() {{add("GeneralSettings"); add("name"); add("ip"); add("port"); add("username"); add("pass"); }};
SettingsContainer = R.id.FragmentContainerGeneralSettings;
SettingsTag = getString(R.string.navdrawer_generalsettings);
SettingsVariableFragment = new GeneralSettingsVariableFragment();
SettingsEmptyFragment = new GeneralSettingsEmptyFragment();
} else {
Log.e(tag, "String Base not recognised");
return;
}
AmountOfEntries = dbHandler.returnArray(base, Data.get(1)).size();
FragmentManager fm = getFragmentManager().findFragmentByTag(SettingsTag).getChildFragmentManager();
if ((dbHandler.returnArray(base, Data.get(1))).size() == 0 ) {
// Log.d(tag, "SettingsContainer1: " + String.valueOf(SettingsContainer) + "; SettingsEmtpyFragment1: " + SettingsEmptyFragment + "; Base1: " + base);
fm.beginTransaction().add(SettingsContainer, SettingsEmptyFragment, (base + "EmptyFragment")).commit();
fm.executePendingTransactions();
return;
}
if (AmountOfEntries > 0) {
String EmptyFragName = (base + "EmptyFragment");
if ((fm.findFragmentByTag(EmptyFragName)) != null) {
fm.beginTransaction().remove(fm.findFragmentByTag(EmptyFragName)).commit();
fm.executePendingTransactions();
}
for (int i = 0; i < AmountOfEntries; i++) {
ArrayList<String> fragmentData = new ArrayList<>();
for (int k=1; k < Data.size(); k++) {
int j=k-1;
fragmentData.set(j, (dbHandler.returnArray(base, Data.get(k)).get(j)));
}
if (token.equalsIgnoreCase("edit")) {
LinearLayout linearLayout = (LinearLayout) findViewById(SettingsContainer);
linearLayout.removeAllViews();
DrawVariableFragments(base ,"draw");
} else if (token.equalsIgnoreCase("add")) {
if (fm.findFragmentByTag(fragmentData.get(i)) == null) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
} else if (token.equalsIgnoreCase("draw")) {
fm.beginTransaction().add(SettingsContainer, SettingsVariableFragment, fragmentData.get(0)).commit();
fm.executePendingTransactions();
if (base.equalsIgnoreCase("StuffManager")) {
((StuffManagerVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1));
} else if (base.equalsIgnoreCase("GeneralSettings")) {
((GeneralSettingsVariableFragment) fm
.findFragmentByTag(fragmentData.get(i)))
.setText(fragmentData.get(0), fragmentData.get(1), fragmentData.get(2), fragmentData.get(3));
}
}
}
} else {
Log.d("TEST", "WTF, nameArray.size != 0 && !> 0");
}
}
}
GeneralSettingsFragment（代码段）
package com.example.fragments.Settings;
public class GeneralSettingsFragment extends Fragment {
MainActivity ma;
DBHandler dbHandler;
private static Menu optionsMenu;
public static boolean hideDeleteAllButton = false;
LinearLayout linearLayout;
View rootView;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_generalsettings, container, false);
ma = (MainActivity) getActivity();
linearLayout = (LinearLayout) rootView.findViewById(R.id.FragmentContainerGeneralSettings);
if (linearLayout == null) {
Log.e("GMF", "Layout is null");
} else if (linearLayout.getChildCount() == 0) {
GeneralSettingsInitialInputDialog GSIID = new GeneralSettingsInitialInputDialog();
GSIID.show(getFragmentManager(), "dialog");
hideDeleteAllButton = true;
} else {
hideDeleteAllButton = false;
}
ma.DrawVariableFragments("GeneralSettings", "draw");
return rootView;
}
}
您仍在以不受支持的方式做事。在 MainActivity.DrawVariableFragments() 中，您正在创建一个新的 GeneralSettingsVariableFragment()，然后对其调用 getChildFragmentManager() 并尝试提交片段。
GeneralSettingsFragment 尚未附加到 Activity，因此它没有主机。这会引发您在尝试提交 FragmentTransaction.
IllegalStateException("Activity has been destroyed") 异常
不清楚为什么要创建一个新的 GeneralSettingsVariableFragment，而您已经在其中的一个新实例中。
要正确查找现有片段，请使用 getFragmentManager().findFragmentByTag(...) 或 getFragmentManager().findFragmentById(...)。