android之Fragment的bug解決
來源：程序員人生 發(fā)布時間：2014-12-24 08:51:33 閱讀次數(shù)：3788次
最近做1個功能，當(dāng)?shù)?次進(jìn)入1個界面的時候出現(xiàn)1個奇怪的bug,以下面詳細(xì)的log信息：
10-01 13:36:23.549: E/AndroidRuntime(14188): Process: com.android.settings, PID: 14188
10-01 13:36:23.549: E/AndroidRuntime(14188): android.view.InflateException: Binary XML file line #43: Error inflating class fragment
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:713)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.view.LayoutInflater.rInflate(LayoutInflater.java:755)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.view.LayoutInflater.inflate(LayoutInflater.java:492)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.view.LayoutInflater.inflate(LayoutInflater.java:397)
10-01 13:36:23.549: E/AndroidRuntime(14188): at com.android.settings.
accessibility.ToggleCaptioningPreferenceFragment.onCreateView(ToggleCaptioningPreferenceFragment.java:69)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.Fragment.performCreateView(Fragment.java:1700)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.BackStackRecord.run(BackStackRecord.java:698)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.os.Handler.handleCallback(Handler.java:808)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.os.Handler.dispatchMessage(Handler.java:103)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.os.Looper.loop(Looper.java:193)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.ActivityThread.main(ActivityThread.java:5333)
10-01 13:36:23.549: E/AndroidRuntime(14188): at java.lang.reflect.Method.invokeNative(Native Method)
10-01 13:36:23.549: E/AndroidRuntime(14188): at java.lang.reflect.Method.invoke(Method.java:515)
10-01 13:36:23.549: E/AndroidRuntime(14188): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
10-01 13:36:23.549: E/AndroidRuntime(14188): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:640)
10-01 13:36:23.549: E/AndroidRuntime(14188): at dalvik.system.NativeStart.main(Native Method)
10-01 13:36:23.549: E/AndroidRuntime(14188): Caused by: java.lang.IllegalArgumentException: Binary XML file line #43: Duplicate id 0x7f0b0034, tag null, or parent id 0xffffffff with another fragment for com.android.settings.
accessibility.CaptionPropertiesFragment
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.app.Activity.onCreateView(Activity.java:4912)
10-01 13:36:23.549: E/AndroidRuntime(14188): at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:689)
如上的log信息可以知道：加載了1個（Duplicate）重復(fù)的Fragment（CaptionPropertiesFragment）。問題是代碼應(yīng)當(dāng)是沒有問題的！具體看看我系的代碼：
public class ToggleCaptioningPreferenceFragment extends Fragment {
private static final float DEFAULT_FONT_SIZE = 48f;
private CaptionPropertiesFragment mPropsFragment;
private SubtitleView mPreviewText;
private CaptioningManager mCaptioningManager;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mCaptioningManager = (CaptioningManager) getActivity()
.getSystemService(Context.CAPTIONING_SERVICE);
}
@Override
public View onCreateView(
LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
final View rootView = inflater.inflate(R.layout.captioning_preview, container, false);
// We have to do this now because PreferenceFrameLayout looks at it
// only when the view is added.
if (container instanceof PreferenceFrameLayout) {
((PreferenceFrameLayout.LayoutParams) rootView.getLayoutParams()).removeBorders = true;
}
return rootView;
}
從報錯信息可以知道出錯的代碼：final View rootView = inflater.inflate(R.layout.captioning_preview, container, false);
那末報錯信息說是加載了重復(fù)的Fragment（CaptionPropertiesFragment）。實際上這個重復(fù)的Fragment在這個layout文件里面布局的：R.layout.captioning_preview。
很明顯，就是第1次進(jìn)入這個界面，再退出的時候，這個用過的Fragment（CaptionPropertiesFragment）沒有remove掉！從而出現(xiàn)了兩個問題：
（1）為何會出現(xiàn)這個Fragment（CaptionPropertiesFragment）沒有remove,
（2）怎樣解決這個問題！
在activity中不同的frament之間項目替換的時候，F(xiàn)ragmentManager只會remove和add這些frament，但是這些frament里面自己加載的frament（這里就是我們的CaptionPropertiesFragment）是沒有被remove. 很明顯這是1個缺點(diǎn)！由于后1個frament（CaptionPropertiesFragment）很明顯是依賴與他的父frament的，應(yīng)當(dāng)同時遞歸的remove.
那末如何解決這個問題呢！很明顯就是在不用這個frament（ToggleCaptioningPreferenceFragment）的時候把他里面加載的frament給remove掉！這個操作在ToggleCaptioningPreferenceFragment的onDestroyView()里面就能夠解決問題了！以下代碼：
@Override
public void onDestroyView() {
super.onDestroyView();
if(mPropsFragment != null){
FragmentManager f = getFragmentManager();
if(f != null && !f.isDestroyed()){
final FragmentTransaction ft = f.beginTransaction();
if(ft != null){
ft.remove(mPropsFragment).commit();
}
}
}
}
這里要注意f.isDestroyed()這樣來判斷是不是這個FragmentManager處于Destroyed，如果不加這個判斷的話，橫豎屏切換時候會出錯！
注意：對這個問題，網(wǎng)上有各種無效的解決辦法。
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