添加嵌套的片段后，已创建父片段视图 [英] Add Nested Fragment after Parent Fragment view is already created
问题描述
我想创建一个片段，它有一个公共的方法添加子片段本身。
I am trying to create a Fragment which has a public method for adding child Fragments to itself.
我一直在读通过潜在的类似问题，但没有发现任何帮助至今。我已经减少这个问题降低到如下所示的简单测试应用程序。
I've been reading through potentially similar questions but haven't found anything to help so far. I've reduced the problem down to a simple test app shown below.
在弗拉加已添加到主布局，我称之为公共方法 fragA.addFragB（）来得到它FragmentClassB的一个实例添加到本身，而是这会导致测试应用程序崩溃，这表明活动已被破坏（见LogCat中在文章末尾）。这是否意味着弗拉加已被破坏，所以我不能添加 fragB 来呢，还是意味着 fragB 已被破坏，所以我不能将其添加到弗拉加？还是意味着别的东西完全？
Once fragA has been added to the main layout, I call the public method fragA.addFragB() to get it to add an instance of FragmentClassB to itself, but this causes the test app to crash, indicating "Activity has been destroyed" (see LogCat at the end of the post). Does this mean fragA has been destroyed so I can't add fragB to it, or does it mean fragB has been destroyed so I can't add it to fragA? Or does it mean something else entirely?
MainActivity.java
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fragMan = getSupportFragmentManager();
// add Fragment A to the main linear layout
FragmentTransaction fragTrans = fragMan.beginTransaction();
FragmentClassA fragA = new FragmentClassA();
fragTrans.add(R.id.mainLinearLayout, fragA);
fragTrans.addToBackStack("A");
fragTrans.commit();
// get Fragment A to add a Fragment B to itself
fragA.addFragB();
}
}
activity_main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<LinearLayout
android:id="@+id/mainLinearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:orientation="horizontal" >
</LinearLayout>
</RelativeLayout>
FragmentClassA.java
public class FragmentClassA extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_a, container, false);
}
public void addFragB() {
FragmentManager childFragMan = getChildFragmentManager();
FragmentTransaction childFragTrans = childFragMan.beginTransaction();
FragmentClassB fragB = new FragmentClassB();
childFragTrans.add(R.id.fragA_LinearLayout, fragB);
childFragTrans.addToBackStack("B");
childFragTrans.commit();
}
}
fragment_a.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/fragA_LinearLayout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
</LinearLayout>
FragmentClassB.java
public class FragmentClassB extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_b, container, false);
}
}
fragment_b.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
LogCat中
11-18 16:17:05.627: E/AndroidRuntime(14351): FATAL EXCEPTION: main
11-18 16:17:05.627: E/AndroidRuntime(14351): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nestedfragmenttest/com.example.nestedfragmenttest.MainActivity}: java.lang.IllegalStateException: Activity has been destroyed
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread.access$600(ActivityThread.java:141)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.os.Handler.dispatchMessage(Handler.java:99)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.os.Looper.loop(Looper.java:137)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-18 16:17:05.627: E/AndroidRuntime(14351): at java.lang.reflect.Method.invokeNative(Native Method)
11-18 16:17:05.627: E/AndroidRuntime(14351): at java.lang.reflect.Method.invoke(Method.java:525)
11-18 16:17:05.627: E/AndroidRuntime(14351): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-18 16:17:05.627: E/AndroidRuntime(14351): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-18 16:17:05.627: E/AndroidRuntime(14351): at dalvik.system.NativeStart.main(Native Method)
11-18 16:17:05.627: E/AndroidRuntime(14351): Caused by: java.lang.IllegalStateException: Activity has been destroyed
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.support.v4.app.FragmentManagerImpl.enqueueAction(FragmentManager.java:1365)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.support.v4.app.BackStackRecord.commitInternal(BackStackRecord.java:595)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.support.v4.app.BackStackRecord.commit(BackStackRecord.java:574)
11-18 16:17:05.627: E/AndroidRuntime(14351): at com.example.nestedfragmenttest.FragmentClassA.addFragB(FragmentClassA.java:26)
11-18 16:17:05.627: E/AndroidRuntime(14351): at com.example.nestedfragmenttest.MainActivity.onCreate(MainActivity.java:25)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.Activity.performCreate(Activity.java:5133)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
11-18 16:17:05.627: E/AndroidRuntime(14351): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
11-18 16:17:05.627: E/AndroidRuntime(14351): ... 11 more
编辑：
ianhanniballake的答案，并GrIsHu后来的答案，扩展了同一个点均出现了有助于指出了问题的根源。然而，这引起了另一个问题。
最终目的是使FragmentClassA将是一个库的一部分。它可以为多个的情况下使用，并FragmentClassB实例的数量会有所不同，或者甚至有可能没有。因此，我需要能够触发加成子片段的给FragmentClassA的任何实例从父活性。我刚刚看了一下保持弗拉加在 MainActivity A类级别的变量，然后调用 fragA.AddFragB（）在 MainActivity 的 onActivityCreated（）的方法，但它不能用于被覆盖。有什么想法？
ianhanniballake's answer and GrIsHu's later answer which expands on the same point have both been helpful in pointing out the root of the problem. However this raises a further issue.
The final intention is that FragmentClassA will be part of a library. It will be used in multiple situations and the number of FragmentClassB instances will vary, or there may even be none. Hence I need to be able to trigger the addition of the child fragments to any instance of FragmentClassA from the parent activity. I've just had a look at keeping fragA as a class level variable in MainActivity and then calling fragA.AddFragB() in the MainActivity's onActivityCreated() method, but it is not available to be overridden. Any thoughts?
推荐答案
您不能直接加载你的弗拉加已宣布的片段。该碎裂将通过调用方法被加载，然后再之后就可以加载FragmentB addFragB（）从弗拉加的 onCreateView（）方法。
You can not directly load the fragment which you have declared in FragA. The FragmentA will be loaded first and then after you can load the FragmentB by calling the method addFragB() from your fragA's onCreateView() method.
试用如下：
删除线 fragA.addFragB（）; 从您的 MainActivity
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
FragmentManager fragMan = getSupportFragmentManager();
// add Fragment A to the main linear layout
FragmentTransaction fragTrans = fragMan.beginTransaction();
FragmentClassA fragA = new FragmentClassA();
fragTrans.add(R.id.mainLinearLayout, fragA);
fragTrans.addToBackStack("A");
fragTrans.commit();
}
}
和尝试加载 FragmentB 从碎裂如下：
public class FragmentClassA extends Fragment {
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
addFragB(); //Call and load fragment B here.
return inflater.inflate(R.layout.fragment_a, container, false);
}
public void addFragB() {
FragmentManager childFragMan = getChildFragmentManager();
FragmentTransaction childFragTrans = childFragMan.beginTransaction();
FragmentClassB fragB = new FragmentClassB();
childFragTrans.add(R.id.fragA_LinearLayout, fragB);
childFragTrans.addToBackStack("B");
childFragTrans.commit();
}
}
这篇关于添加嵌套的片段后，已创建父片段视图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！
