我有一个片段，其中3个按钮附加到名为MainActivity的活动类。当用户点击第一个按钮时，使用startActivityForResult()调用另一个活动。在第二个活动中，用户可以选择一些显示的文件。选择后，一旦用户点击Done，用户将被带回3个按钮的原始片段
我在super.onActivityResult(requestCode, resultCode, data);中呼叫MainActivity，以便将呼叫转移到片段的onActivityResult()。
在片段onActivityResult()中，我收到所有选定的文件。我压缩它们并计算这个zip文件的大小。如果尺寸大于预定义尺寸，我会向用户显示提醒，当用户点击OK时，我会再次使用startActivityForResult()调用文件选择活动。
但是在onClick的{{1}}事件中，我得到一个例外AlertDialog。片段渲染得很好，为什么它没有附加到活动？
以下是相关的代码段：
片段fragment not attached to activity：
onActivityResult此方法启动文件浏览器活动：
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
Log.d("HF", "OAR");
if (requestCode == SELECT_FILES) {
... code to zip the file
int size = getFileSize();
if (fileName != null && new File(fileName).length() > size) {
new AlertDialog.Builder(getActivity())
.setTitle("Error")
.setMessage("The message")
.setIcon(android.R.drawable.ic_dialog_alert)
.setPositiveButton("ok", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
if (isAdded())
startFileBrowser();
else {
Log.d("HF", "not attached");
}
}
})
.show();
}
}
}
private void startFileBrowser() {
Intent intent = new Intent(activity, FileBrowserActivity.class);
startActivityForResult(intent, SELECT_FILES);
}
：
ClickListener片段中的selectFilesButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (commonMethods.shouldBeActive(R.id.select_printer_id)) {
new AlertDialog.Builder(getActivity())
.setTitle(getString(R.string.file_replace_title))
.setMessage(getString(R.string.file_replace_message))
.setIcon(android.R.drawable.ic_dialog_alert)
.setPositiveButton(R.string.continue_string, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
startFileBrowser();
}
})
.setNegativeButton(android.R.string.cancel, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
})
.show();
} else
startFileBrowser();
}
});
方法：
onAttach例外的Stacktrace：
private Activity activity;
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof Activity){
Log.d("HF", "OA");
activity = (Activity) context;
}
}
activity_main.xml中
E/UncaughtException: java.lang.IllegalStateException: Fragment HomeFragment{19909} not attached to Activity
at android.support.v4.app.Fragment.startActivityForResult(Fragment.java:952)
at android.support.v4.app.Fragment.startActivityForResult(Fragment.java:943)
at com.package.HomeFragment.startFileBrowser(HomeFragment.java:305)
at com.package.HomeFragment.access$000(HomeFragment.java:45)
at com.package.HomeFragment$1.onClick(HomeFragment.java:119)
at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:161)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
D/FA: Logging event (FE): _ae, Bundle[{_o=crash, _sc=HomeActivity, _si=4833782661551315669, timestamp=1484755442671, fatal=1}]
E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.IllegalStateException: Fragment HomeFragment{19909} not attached to Activity
at android.support.v4.app.Fragment.startActivityForResult(Fragment.java:952)
at android.support.v4.app.Fragment.startActivityForResult(Fragment.java:943)
at com.package.HomeFragment.startFileBrowser(HomeFragment.java:305)
at com.package.HomeFragment.access$000(HomeFragment.java:45)
at com.package.HomeFragment$1.onClick(HomeFragment.java:119)
at android.support.v7.app.AlertController$ButtonHandler.handleMessage(AlertController.java:161)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
在“MainActivity”中设置片段的方法
<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<!-- The ActionBar -->
<include
layout="@layout/toolbar"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
<!-- The main content view -->
<FrameLayout
android:id="@+id/flContent"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
<!-- The navigation drawer -->
<android.support.design.widget.NavigationView
android:id="@+id/nvView"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="start"
android:background="@android:color/white"
app:itemTextColor="?android:textColorPrimary"
app:menu="@menu/nav_drawer_menu" />
</android.support.v4.widget.DrawerLayout>
我在private void setupFragment(Class fragmentClass, MenuItem menuItem) {
try {
Fragment fragment = (Fragment) fragmentClass.newInstance();
FragmentManager fragmentManager = getSupportFragmentManager();
fragmentManager.beginTransaction().replace(R.id.flContent, fragment).commit();
menuItem.setChecked(true);
setTitle(menuItem.getTitle());
drawerLayout.closeDrawers();
} catch (InstantiationException | IllegalAccessException e) {
e.printStackTrace();
}
}
：
onCreate()