IllegalStateException:无法更改片段标记为android:switcher android:switcher [英] IllegalStateException: Can't change tag of fragment was android:switcher now android:switcher
本文介绍了IllegalStateException:无法更改片段标记为android:switcher android:switcher的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我的活动使用TabLayout + ViewPager.
此处的选项卡和页面数是动态的，具体取决于从服务器获取的数据.
The number of tabs and pages here are dynamic depending on the data fetch from the server.
崩溃是通过Crashlytics报告的，我无法复制它.
The crash are reported via Crashlytics, I'm not able to replicate it.
我的活动代码:
@Override
protected void onCreate(Bundle savedInstanceState) {
boolean isAppRestarting = PrefUtils.getBoolean("app_restarting", false);
if (isAppRestarting) {
super.onCreate(null);
this.savedInstanceState = null;
} else {
super.onCreate(savedInstanceState);
this.savedInstanceState = savedInstanceState;
}
initSlidingTabs();
fetchSomeData(); // see onDataFetched() below
}
private void initSlidingTabs() {
List<FragmentWithTitle> sdsTabs = new ArrayList<>();
Logger.i("There is saved instance state");
ArrayList<String> titles = savedInstanceState.getStringArrayList(TAB_TITLES);
if (titles != null) {
for (int i = 0; i < titles.size(); i++) {
if (getFragment(i) != null) {
sdsTabs.add(new FragmentWithTitle(getFragment(i), titles.get(i)));
}
}
}
mTabsAdapter = new MyTabsAdapter(getSupportFragmentManager(), sdsTabs);
mViewPager = (ViewPager) findViewById(R.id.layoutViewPagerSlidingTabs);
mViewPager.setAdapter(mTabsAdapter);
mViewPager.setOffscreenPageLimit(2);
mSlidingTabs = (TabLayout) findViewById(R.id.tabs);
mSlidingTabs.setupWithViewPager(mViewPager);
}
@Override
protected void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
if (mTabsAdapter != null) {
outState.putStringArrayList(TAB_TITLES, mTabsAdapter.getTitles());
}
}
private Fragment getFragment(int position) {
return savedInstanceState == null ? mTabsAdapter.getItem(position) : getSupportFragmentManager()
.findFragmentByTag(getFragmentTag(position));
}
private String getFragmentTag(int position) {
return "android:switcher:" + R.id.layoutViewPagerSlidingTabs + ":" + position;
}
/**
Callback of fetchData() in onCreate()
*/
private void onDataFetched(List<AbcObject> abcObjects) {
if (savedInstanceState == null) {
if (abcObjects != null) {
for (AbcObject abcObject : abcObjects) {
mTabsAdapter.addTab(new FragmentWithTitle(AbcFragment.newInstance(), abcObject.getTitle()));
}
}
} else {
Logger.d("There is saved instance state");
ArrayList<String> titles = savedInstanceState.getStringArrayList(TAB_TITLES);
if (titles != null) {
for (int i = 0; i < titles.size(); i++) {
mTabsAdapter.addTab(new FragmentWithTitle(getFragment(i), titles.get(i)));
}
}
}
mTabsAdapter.notifyDataSetChanged();
}
MyTabsAdapter:
MyTabsAdapter:
public class MyTabsAdapter extends FragmentPagerAdapter {
private List<FragmentWithTitle> mTabs = new ArrayList<>();
public MyTabsAdapter(FragmentManager fm, List<FragmentWithTitle> sdsTabs) {
super(fm);
this.mTabs = sdsTabs;
}
@Override
public Fragment getItem(int position) {
return mTabs.get(position).getFragment();
}
@Override
public CharSequence getPageTitle(int position) {
return mTabs.get(position).getTitle();
}
@Override
public int getCount() {
return this.mTabs.size();
}
public int getItemPosition(Object object) {
return POSITION_NONE;
}
/**
* Prevent java.lang.IllegalStateException Fragment no longer exists for key android:target_state: index 5
*
* @return
*/
@Override
public Parcelable saveState() {
return null;
}
public ArrayList<String> getTitles() {
ArrayList<String> titles = new ArrayList<>();
for (int i = 0; i < mTabs.size(); i++) {
titles.add((String) mTabs.get(i).getTitle());
}
return titles;
}
public void addTab(FragmentWithTitle fragmentWithTitle) {
mTabs.add(fragmentWithTitle);
}
}
完整的堆栈跟踪:
Fatal Exception: java.lang.IllegalStateException: Can't change tag of fragment ShopFrag{4dbb6e90 #0 id=0x7f1200dd android:switcher:2131886301:0}: was android:switcher:2131886301:0 now android:switcher:2131886301:9
at android.support.v4.app.BackStackRecord.doAddOp(BackStackRecord.java:444)
at android.support.v4.app.BackStackRecord.add(BackStackRecord.java:426)
at android.support.v4.app.FragmentPagerAdapter.instantiateItem(FragmentPagerAdapter.java:103)
at android.support.v4.view.ViewPager.addNewItem(ViewPager.java:1038)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1252)
at android.support.v4.view.ViewPager.populate(ViewPager.java:1120)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1646)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:17396)
at android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1081)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1410)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:17396)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5365)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2505)
at android.view.View.measure(View.java:17396)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2175)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1316)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1513)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1200)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6401)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:803)
at android.view.Choreographer.doCallbacks(Choreographer.java:603)
at android.view.Choreographer.doFrame(Choreographer.java:573)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:789)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:157)
at android.app.ActivityThread.main(ActivityThread.java:5335)
at java.lang.reflect.Method.invokeNative(Method.java)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
at dalvik.system.NativeStart.main(NativeStart.java)
FragmentWithTitle:
FragmentWithTitle:
public class FragmentWithTitle {
public FragmentWithTitle(Fragment mFragment, CharSequence mTitle) {
this.fragment = mFragment;
this.title = mTitle;
}
public Fragment getFragment() {
return fragment;
}
public void setFragment(Fragment fragment) {
this.fragment = fragment;
}
public CharSequence getTitle() {
return title;
}
public void setTitle(CharSequence title) {
this.title = title;
}
private Fragment fragment;
private CharSequence title;
}
推荐答案
FragmentPagerAdapter已经为您缓存了Fragments.每个片段都分配有一个标签，然后FragmentPagerAdapter尝试调用findFragmentByTag.如果findFragmentByTag的结果为null，则仅调用 getItem().
The FragmentPagerAdapter already caches the Fragments for you. Each fragment is assigned a tag, and then the FragmentPagerAdapter tries to call findFragmentByTag. It only calls getItem() if the result from findFragmentByTag is null.
您可能会收到此错误，因为您要将相同的片段实例添加到列表中.您应该为每个页面创建一个新实例.
表格文件示例:
//...
public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
super(fm);
}
@Override
public int getCount() {
return NUM_ITEMS;
}
@Override
public Fragment getItem(int position) {
return ArrayListFragment.newInstance(position);// IMPORTANT
}
}
//..
主线程:从ViewPager中获取片段
这篇关于IllegalStateException:无法更改片段标记为android:switcher android:switcher的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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