我创建了一个全新的项目来演示我的问题.基本上,我的片段有两个RadioButton.在onCreateView时,我总是使用radioButtonFirst.setChecked(true);.但是,如果我检查radioButtonSecond,然后按“返回”按钮进行导航,下次打开它,它将自动检查radioButtonSecond.这种行为破坏了我的逻辑.
MainActivity.java
public class MainActivity extends AppCompatActivity {
private WeirdFragment weirdFragment;
private FragmentManager fragmentManager;
private FragmentTransaction fragmentTransaction;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
weirdFragment = new WeirdFragment();
fragmentManager = getSupportFragmentManager();
}
public void openFragment(View v){
fragmentTransaction = fragmentManager.beginTransaction();
fragmentTransaction.add(R.id.container,weirdFragment);
fragmentTransaction.addToBackStack(null);
fragmentTransaction.commit();
}
}
WeirdFragment.java
public class WeirdFragment extends Fragment {
private RadioButton radioButtonFirst;
private RadioButton radioButtonSecond;
private Button buttonReturn;
@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater,@Nullable ViewGroup container,@Nullable Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_weird,container,false);
radioButtonFirst = view.findViewById(R.id.radio_button_first);
radioButtonSecond = view.findViewById(R.id.radio_button_second);
buttonReturn = view.findViewById(R.id.button_return);
radioButtonFirst.setChecked(true);
// I decide to set a listener right here,to see what happened to my radio button. So this listener will be removed in my real project.
radioButtonSecond.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,boolean isChecked) {
Log.v("weird","i got here");
}
});
buttonReturn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
getFragmentManager().beginTransaction().remove(WeirdFragment.this).commit();
}
});
return view;
}
}
activity_main.xml
<Button
android:id="@+id/button_open"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="openFragment"
android:text="Open"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<FrameLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toBottomOf="@id/button_open" />
fragment_weird.xml
<RadioGroup
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintTop_toTopOf="parent">
<RadioButton
android:id="@+id/radio_button_first"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:checked="true"
android:text="First" />
<RadioButton
android:id="@+id/radio_button_second"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="Second" />
</RadioGroup>
<Button
android:id="@+id/button_return"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Return"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" />
我在log语句中设置了一个断点.当用户操作触发该断点时,堆栈跟踪将如下所示：
onCheckedChanged:31,WeirdFragment$1 (com.peanut.myweirdradiobutton)
setChecked:154,CompoundButton (android.widget)
toggle:113,CompoundButton (android.widget)
toggle:78,RadioButton (android.widget)
performClick:118,CompoundButton (android.widget)
run:19866,View$PerformClick (android.view)
handleCallback:739,Handler (android.os)
dispatchMessage:95,Handler (android.os)
loop:135,Looper (android.os)
main:5254,ActivityThread (android.app)
invoke:-1,Method (java.lang.reflect)
invoke:372,Method (java.lang.reflect)
run:903,ZygoteInit$MethodAndArgsCaller (com.android.internal.os)
main:698,ZygoteInit (com.android.internal.os)
但是当断断续续触发断点时,stracktrace看起来像这样：
onCheckedChanged:31,CompoundButton (android.widget)
onRestoreInstanceState:522,CompoundButton (android.widget)
dispatchRestoreInstanceState:13740,View (android.view)
dispatchRestoreInstanceState:2893,ViewGroup (android.view)
dispatchRestoreInstanceState:2893,ViewGroup (android.view)
restoreHierarchyState:13718,View (android.view)
restoreViewState:494,Fragment (android.support.v4.app)
moveToState:1486,FragmentManagerImpl (android.support.v4.app)
moveFragmentToExpectedState:1784,FragmentManagerImpl (android.support.v4.app)
moveToState:1852,FragmentManagerImpl (android.support.v4.app)
executeOps:802,BackStackRecord (android.support.v4.app)
executeOps:2625,FragmentManagerImpl (android.support.v4.app)
executeOpsTogether:2411,FragmentManagerImpl (android.support.v4.app)
removeRedundantOperationsAndExecute:2366,FragmentManagerImpl (android.support.v4.app)
execPendingActions:2273,FragmentManagerImpl (android.support.v4.app)
run:733,FragmentManagerImpl$1 (android.support.v4.app)
handleCallback:739,ZygoteInit (com.android.internal.os)
因此,我可以看到它是onRestoreInstanceState检查我的radioButtonSecond.但是我不知道如何预防.我正在考虑的事情：
>在onViewStateRestored中执行我的逻辑.但这不是一个干净的解决方案.
>每次需要打开片段时都要重新创建.但是,在创建新片段时,我的初始化阶段成本很高,我不应该这样做.
在我的真实项目中,此片段就像我的应用程序中的某项设置一样,它具有“取消”和“确定”按钮.因此,我希望片段每次打开时都处于默认状态,因为我认为,例如,用户可能配置了很多东西,但是按“取消”,则可以看到所有视图都处于默认状态状态,而不是已配置的状态(可能是这种想法导致了我的问题,这是一种良好的用户体验吗？)
因此,如何防止未经我允许的片段恢复其状态？
