问题
Null returned from ((MessageTextFragment)fragment).setActionButtonStateListener(bAction);
Here is the SetupMessageFragment.java
package com.mayday.md.fragment;
import com.mayday.md.MainActivity;
import com.mayday.md.R;
import com.mayday.md.WizardActivity;
import com.mayday.md.adapter.PageItemAdapter;
import com.mayday.md.common.AppConstants;
import com.mayday.md.common.AppUtil;
import com.mayday.md.common.ApplicationSettings;
import com.mayday.md.common.MyTagHandler;
import com.mayday.md.data.PBDatabase;
import com.mayday.md.model.Page;
import com.mayday.md.model.PageItem;
import com.mayday.md.model.SMSSettings;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.text.Html;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;
/**
* Created by aoe on 12/12/13.
*/
public class SetupMessageFragment extends Fragment {
private EditText smsEditText;
private static final String PAGE_ID = "page_id";
private static final String PARENT_ACTIVITY = "parent_activity";
private Activity activity;
DisplayMetrics metrics;
TextView tvTitle, tvContent, tvIntro, tvWarning;
Button bAction;
ListView lvItems;
LinearLayout llWarning;
Page currentPage;
PageItemAdapter pageItemAdapter;
public static SetupMessageFragment newInstance(String pageId, int parentActivity) {
SetupMessageFragment f = new SetupMessageFragment();
Bundle args = new Bundle();
args.putString(PAGE_ID, pageId);
args.putInt(PARENT_ACTIVITY, parentActivity);
f.setArguments(args);
return(f);
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_type_interactive_message, container, false);
tvTitle = (TextView) view.findViewById(R.id.fragment_title);
tvIntro = (TextView) view.findViewById(R.id.fragment_intro);
tvContent = (TextView) view.findViewById(R.id.fragment_contents);
bAction = (Button) view.findViewById(R.id.fragment_action);
bAction.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Log.e(">>>>", "action button pressed");
String msg = getSMSSettingsFromView();
SMSSettings.saveMessage(activity, msg);
displaySettings(msg);
String pageId = currentPage.getAction().get(0).getLink();
int parentActivity = getArguments().getInt(PARENT_ACTIVITY);
Intent i;
if(parentActivity == AppConstants.FROM_WIZARD_ACTIVITY){
i = new Intent(activity, WizardActivity.class);
} else{
// AppUtil.showToast("Message saved.", 1000, activity);
String confirmation = (currentPage.getAction().get(0).getConfirmation() == null)
? AppConstants.DEFAULT_CONFIRMATION_MESSAGE
: currentPage.getAction().get(0).getConfirmation();
Toast.makeText(activity, confirmation, Toast.LENGTH_SHORT).show();
i = new Intent(activity, MainActivity.class);
}
i.putExtra("page_id", pageId);
startActivity(i);
if(parentActivity == AppConstants.FROM_MAIN_ACTIVITY){
activity.finish();
}
}
});
lvItems = (ListView) view.findViewById(R.id.fragment_item_list);
llWarning = (LinearLayout) view.findViewById(R.id.ll_fragment_warning);
tvWarning = (TextView) view.findViewById(R.id.fragment_warning);
lvItems.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
PageItem selectedItem = (PageItem) parent.getItemAtPosition(position);
String pageId = selectedItem.getLink();
int parentActivity = getArguments().getInt(PARENT_ACTIVITY);
Intent i;
if(parentActivity == AppConstants.FROM_WIZARD_ACTIVITY){
i = new Intent(activity, WizardActivity.class);
} else{
i = new Intent(activity, MainActivity.class);
}
i.putExtra("page_id", pageId);
startActivity(i);
}
});
return view;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
activity = getActivity();
if (activity != null) {
metrics = new DisplayMetrics();
activity.getWindowManager().getDefaultDisplay().getMetrics(metrics);
Fragment fragment = getFragmentManager().findFragmentById(R.id.sms_message);
((MessageTextFragment)fragment).setActionButtonStateListener(bAction);
smsEditText = (EditText) fragment.getView().findViewById(R.id.message_edit_text);
String currentMsg = SMSSettings.retrieveMessage(activity);
if(currentMsg != null) {
displaySettings(currentMsg);
}
bAction.setEnabled(!smsEditText.getText().toString().trim().equals(""));
String pageId = getArguments().getString(PAGE_ID);
String selectedLang = ApplicationSettings.getSelectedLanguage(activity);
PBDatabase dbInstance = new PBDatabase(activity);
dbInstance.open();
currentPage = dbInstance.retrievePage(pageId, selectedLang);
dbInstance.close();
tvTitle.setText(currentPage.getTitle());
if(currentPage.getContent() == null)
tvContent.setVisibility(View.GONE);
else
tvContent.setText(Html.fromHtml(currentPage.getContent(), null, new MyTagHandler()));
if(currentPage.getIntroduction() == null)
tvIntro.setVisibility(View.GONE);
else
tvIntro.setText(currentPage.getIntroduction());
if(currentPage.getWarning() == null)
llWarning.setVisibility(View.GONE);
else
tvWarning.setText(currentPage.getWarning());
bAction.setText(currentPage.getAction().get(0).getTitle());
pageItemAdapter = new PageItemAdapter(activity, null);
lvItems.setAdapter(pageItemAdapter);
pageItemAdapter.setData(currentPage.getItems());
AppUtil.updateImages(true, currentPage.getContent(), activity, metrics, tvContent, AppConstants.IMAGE_INLINE);
}
}
private void displaySettings(String msg) {
smsEditText.setText(msg);
}
private String getSMSSettingsFromView() {
String message = smsEditText.getText().toString().trim();
return message;
}
}
The error logs.
02-14 00:56:35.054 26659-26659/com.mayday.md E/SimpleFragment.onPause﹕ settings
02-14 00:56:35.054 26659-26659/com.mayday.md E/MainActivity.onPause﹕ .
02-14 00:56:35.054 26659-26659/com.mayday.md E/MainActivity.onPause﹕ flagRiseFromPause = true
02-14 00:56:35.084 26659-26659/com.mayday.md D/AbsListView﹕ unregisterIRListener() is called
02-14 00:56:35.084 26659-26659/com.mayday.md D/AbsListView﹕ unregisterIRListener() is called
02-14 00:56:35.094 26659-26659/com.mayday.md E/>>>>>﹕ Registering finish activity in oncreate -> BaseFragmentActivity
02-14 00:56:35.114 26659-26659/com.mayday.md E/MainActivity.onCreate﹕ pageId = settings-message
02-14 00:56:35.164 26659-26659/com.mayday.md D/skia﹕ GFXPNG PNG bitmap created width:33 height:72 bitmap id is 282
02-14 00:56:35.164 26659-26659/com.mayday.md D/skia﹕ GFXPNG PNG bitmap created width:33 height:72 bitmap id is 283
02-14 00:56:35.164 26659-26659/com.mayday.md D/skia﹕ GFXPNG PNG bitmap created width:33 height:72 bitmap id is 284
02-14 00:56:35.164 26659-26659/com.mayday.md D/skia﹕ GFXPNG PNG bitmap created width:33 height:72 bitmap id is 285
02-14 00:56:35.204 26659-26659/com.mayday.md D/AbsListView﹕ Get MotionRecognitionManager
02-14 00:56:35.204 26659-26659/com.mayday.md D/AndroidRuntime﹕ Shutting down VM
02-14 00:56:35.204 26659-26659/com.mayday.md W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x41765da0)
02-14 00:56:35.214 26659-26659/com.mayday.md E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.mayday.md, PID: 26659
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.mayday.md/com.mayday.md.MainActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2395)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2453)
at android.app.ActivityThread.access$900(ActivityThread.java:173)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5579)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.mayday.md.fragment.SetupMessageFragment.onActivityCreated(SetupMessageFragment.java:149)
at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1794)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:967)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1126)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1489)
at android.support.v4.app.FragmentActivity.onStart(FragmentActivity.java:548)
at com.mayday.md.MainActivity.onStart(MainActivity.java:219)
at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1177)
at android.app.Activity.performStart(Activity.java:5461)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2368)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2453)
at android.app.ActivityThread.access$900(ActivityThread.java:173)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5579)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1268)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1084)
at dalvik.system.NativeStart.main(Native Method)
回答1:
If ((MessageTextFragment)fragment).setActionButtonStateListener(bAction); is line 219, then you need to make sure that MessageTextFragment was added by the FragmentManager with the id of sms_message and was done before you called it.
You need to change:
Fragment fragment = getFragmentManager().findFragmentById(R.id.sms_message);
((MessageTextFragment)fragment).setActionButtonStateListener(bAction);
smsEditText = (EditText) fragment.getView().findViewById(R.id.message_edit_text);
to something like:
Fragment fragment = new MessageTextFragment();
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.add(R.id.sms_message, fragment).commit();
Fragment fragment2 = getChildFragmentManager().findFragmentById(R.id.sms_message);
((MessageTextFragment) fragment2).setActionButtonStateListener(bAction);
smsEditText = (EditText) fragment2.getView().findViewById(R.id.message_edit_text);
来源：https://stackoverflow.com/questions/28512939/how-can-i-use-set-fragment-inside-my-class-which-extends-the-fragment-class