Android 片段重新加载导致数据丢失
我有一个活动,其中有两个片段用作选项卡。我有一些数据通过bundle传递给片段。问题是我的片段会重新加载,捆绑包会变成null,这会在我尝试获取数据时导致null指针异常。我试图调试,一开始我得到了正确的数据,但后来它重新加载了片段,我得到了错误。我有查看寻呼机,我设置了屏幕外的页面限制,但我仍然得到了错误 我的活动:Android 片段重新加载导致数据丢失,android,android-fragments,android-viewpager,android-tabs,android-bundle,Android,Android Fragments,Android Viewpager,Android Tabs,Android Bundle,我有一个活动,其中有两个片段用作选项卡。我有一些数据通过bundle传递给片段。问题是我的片段会重新加载,捆绑包会变成null,这会在我尝试获取数据时导致null指针异常。我试图调试,一开始我得到了正确的数据,但后来它重新加载了片段,我得到了错误。我有查看寻呼机,我设置了屏幕外的页面限制,但我仍然得到了错误 我的活动: long selectedDayValues = getIntent().getLongExtra("Selected day",0); Bundle bundl
long selectedDayValues = getIntent().getLongExtra("Selected day",0);
Bundle bundle = new Bundle();
bundle.putLong("Selected day", selectedDayValues);
Fragment expensesForCurrentDayFragment = new ProfitsForCurrentDay();
expensesForCurrentDayFragment.setArguments(bundle);
FragmentTransaction transactionExpenses = getSupportFragmentManager().beginTransaction();
transactionExpenses.add(R.id.fragment_profits_current_day, expensesForCurrentDayFragment).commit();
Fragment profitsForCurrentDayFragment = new ExpensesForCurrentDay();
profitsForCurrentDayFragment.setArguments(bundle);
FragmentTransaction transactionProfits = getSupportFragmentManager().beginTransaction();
transactionProfits.add(R.id.fragment_expenses_current_day, profitsForCurrentDayFragment).commit();
// Set up the action bar.
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
tabLayout.addTab(tabLayout.newTab().setText("Expenses"));
tabLayout.addTab(tabLayout.newTab().setText("Profits"));
tabLayout.setTabGravity(TabLayout.GRAVITY_FILL);
final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
final SectionsPagerAdapter adapter = new SectionsPagerAdapter
(getSupportFragmentManager());
viewPager.setAdapter(adapter);
viewPager.setOffscreenPageLimit(2);
我在片段中有这个:
Bundle args = getArguments();
long currentDaySeconds = args.getLong("Selected day", 0);
日志类别:
E/AndroidRuntime: FATAL EXCEPTION: main
E/AndroidRuntime: java.lang.NullPointerException
E/AndroidRuntime: at .ExpensesForCurrentDay.onCreateView(ExpensesForCurrentDay.java:35)
E/AndroidRuntime: at android.support.v4.app.Fragment.performCreateView(Fragment.java:1962)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1026)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1207)
E/AndroidRuntime: at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:738)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1572)
E/AndroidRuntime: at android.support.v4.app.FragmentManagerImpl.executePendingTransactions(FragmentManager.java:545)
E/AndroidRuntime: at android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:141)
E/AndroidRuntime: at android.support.v4.view.ViewPager.populate(ViewPager.java:1106)
E/AndroidRuntime: at android.support.v4.view.ViewPager.populate(ViewPager.java:952)
E/AndroidRuntime: at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1474)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617)
E/AndroidRuntime: at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:399)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime: at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:124)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
E/AndroidRuntime: at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
E/AndroidRuntime: at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1390)
E/AndroidRuntime: at android.widget.LinearLayout.measureVertical(LinearLayout.java:681)
E/AndroidRuntime: at android.widget.LinearLayout.onMeasure(LinearLayout.java:574)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4814)
E/AndroidRuntime: at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
E/AndroidRuntime: at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2148)
E/AndroidRuntime: at android.view.View.measure(View.java:15172)
E/AndroidRuntime: at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1848)
E/AndroidRuntime: at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1100)
E/AndroidRuntime: at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1273)
E/AndroidRuntime: at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:998)
E/AndroidRuntime: at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4212)
E/AndroidRuntime: at android.view.Choreographer$CallbackRecord.run(Choreographer.java:725)
E/AndroidRuntime: at android.view.Choreographer.doCallbacks(Choreographer.java:555)
E/AndroidRuntime: at android.view.Choreographer.doFrame(Choreographer.java:525)
E/AndroidRuntime: at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:711)
E/AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:615)
E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime: at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:4745)
E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
E/AndroidRuntime: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
E/AndroidRuntime: at dalvik.system.NativeStart.main(Native Method)
我试图在onSaveInstanceState中保存数据,但重新加载发生在片段保存其状态之前。将片段的创建移动到FragmentPagerAdapter,正如您在指向文档的漂亮链接中看到的: 您还可以通过以下方式将选项卡的创建委托给适配器:
mTabLayout.setTabsFromPagerAdapter(mAdapter);
在处理片段上的静态输入时,在创建片段之前已知并且没有更改,我使用静态工厂方法,如本例所示 如果右键单击程序包,Android studio还可以帮助您使用工厂方法创建片段→ 新的→ 碎片→ 空白→ 包括片段工厂方法
mTabLayout.setTabsFromPagerAdapter(mAdapter);