android.content.ContextWrapper 处的 NullPointerException [英] NullPointerException at android.content.ContextWrapper
本文介绍了android.content.ContextWrapper 处的 NullPointerException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
当我尝试在正常活动中通过 getResources().getColor(R.color.yellow) 获取颜色时，出现此异常:
When I try to get a color via getResources().getColor(R.color.yellow) in a normal Activity I get this exception:
07-12 11:58:38.019: E/AndroidRuntime(3233): FATAL EXCEPTION: main
07-12 11:58:38.019: E/AndroidRuntime(3233): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.moveinblue.planner/com.moveinblue.planner.controller.plan.PlanDayScreen}: java.lang.NullPointerException
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1993)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2104)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread.access$600(ActivityThread.java:132)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1157)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.os.Handler.dispatchMessage(Handler.java:99)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.os.Looper.loop(Looper.java:137)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread.main(ActivityThread.java:4575)
07-12 11:58:38.019: E/AndroidRuntime(3233): at java.lang.reflect.Method.invokeNative(Native Method)
07-12 11:58:38.019: E/AndroidRuntime(3233): at java.lang.reflect.Method.invoke(Method.java:511)
07-12 11:58:38.019: E/AndroidRuntime(3233): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:789)
07-12 11:58:38.019: E/AndroidRuntime(3233): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:556)
07-12 11:58:38.019: E/AndroidRuntime(3233): at dalvik.system.NativeStart.main(Native Method)
07-12 11:58:38.019: E/AndroidRuntime(3233): Caused by: java.lang.NullPointerException
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.content.ContextWrapper.getResources(ContextWrapper.java:81)
07-12 11:58:38.019: E/AndroidRuntime(3233): at com.moveinblue.planner.controller.plan.PlanDayScreen$4.<init>(PlanDayScreen.java:408)
07-12 11:58:38.019: E/AndroidRuntime(3233): at com.moveinblue.planner.controller.plan.PlanDayScreen.<init>(PlanDayScreen.java:406)
07-12 11:58:38.019: E/AndroidRuntime(3233): at java.lang.Class.newInstanceImpl(Native Method)
07-12 11:58:38.019: E/AndroidRuntime(3233): at java.lang.Class.newInstance(Class.java:1319)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
07-12 11:58:38.019: E/AndroidRuntime(3233): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1984)
07-12 11:58:38.019: E/AndroidRuntime(3233): ... 11 more
有人可以给我一些事后的看法吗?我完全迷路了.
Can anybody give me some hindsight here? I'm totally lost.
活动中的代码:
package com.moveinblue.planner.controller.plan;
import java.text.SimpleDateFormat;
import java.util.BitSet;
import java.util.Calendar;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.AsyncTask;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.AutoCompleteTextView;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.Toast;
import com.moveinblue.api.Login;
import com.moveinblue.api.Planner;
import com.moveinblue.api.UnauthorizedException;
import com.moveinblue.api.io.InvalidURLException;
import com.moveinblue.api.io.OfflineException;
import com.moveinblue.api.model.ModelObject;
import com.moveinblue.api.model.Plan;
import com.moveinblue.api.model.time.Day;
import com.moveinblue.api.model.time.ScheduledThingToDo;
import com.moveinblue.api.model.time.ScheduledTime;
import com.moveinblue.api.model.time.ScheduledTime.TimeOfDay;
import com.moveinblue.planner.R;
import com.moveinblue.planner.controller.GenericPlannerScreen;
import com.moveinblue.planner.controller.thingtodo.ThingsToDoListScreen;
import com.moveinblue.planner.controller.user.LoginScreen;
import com.moveinblue.planner.ui.actionbar.ActionBar;
import com.moveinblue.planner.ui.draganddroplist.DragListener;
import com.moveinblue.planner.ui.draganddroplist.DragNDropListView;
import com.moveinblue.planner.ui.draganddroplist.DropListener;
import com.moveinblue.planner.ui.draganddroplist.RemoveListener;
import com.moveinblue.planner.utils.CommonActionStorage;
import com.moveinblue.planner.utils.CurrentItemsStorage;
import com.moveinblue.planner.utils.adapter.DragNDropAdapter;
import com.moveinblue.planner.utils.adapter.listeners.OnCheckListener;
public class PlanDayScreen extends GenericPlannerScreen {
DragNDropListView lista;
AutoCompleteTextView actv;
String[] dests;
DragNDropAdapter adapter;
private Boolean idDroppedOrDeleted = false;
private BitSet checkedBoxes = new BitSet();
private boolean firstLoad = true;
Day day;
@SuppressWarnings("unused")
private static final String LOG_TAG = PlanDayScreen.class
.getCanonicalName();
@Override
public void load() {
setContentView(R.layout.plan_day_list);
setUpList();
setUpBottomLayout(false);
lista.requestFocus();
}
@Override
protected void loadActionBar() {
Plan p = CurrentItemsStorage.currentPlan;
Calendar c = CurrentItemsStorage.currentDay;
ab = new ActionBar(this, ActionBar.TYPE_LIST);
String date = new SimpleDateFormat("MMM dd, yyyy").format(c.getTime());
date = Character.toUpperCase(date.charAt(0)) + date.substring(1);
date = "(" + date + ")";
String title;
title = (p != null) ? p.name + " " + date : "Draft plan";
ab.setTitle(title);
ab.setBackAction(R.drawable.back, new OnClickListener() {
@Override
public void onClick(View arg0) {
Intent intent = new Intent(PlanDayScreen.this,
PlanTabsScreen.class);
intent.putExtra("tab", 2);
startActivity(intent);
overridePendingTransition(android.R.anim.slide_in_left,
android.R.anim.fade_out);
}
});
CommonActionStorage.setUpActionBar(ab);
}
private void addNewTTD() {
if (getIntent().getBooleanExtra("schedule", false) && firstLoad) {
try {
Calendar c = CurrentItemsStorage.currentDay;
TimeOfDay tod = CurrentItemsStorage.currentTimeOfDaySelectedOption;
Planner.schedule(
CurrentItemsStorage.getCurrentThingToDo().ttdId,
new ScheduledTime(c, tod));
} catch (Exception ex) {
ex.getStackTrace();
}
}
firstLoad = false;
}
/**
* Sets up a bottom bar button
*
* @param id
* The bottom bar button id you want to set
*/
private void setUpBottomButton(int id) {
ImageButton b = (ImageButton) findViewById(id);
switch (id) {
case R.id.buttonBottom1:
if (!areThereCheckedBoxes()) {
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Add TTD to plan
Intent intent = new Intent(PlanDayScreen.this,
ThingsToDoListScreen.class);
startActivity(intent);
}
});
} else {
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Date
}
});
}
break;
case R.id.buttonBottom2:
if (!areThereCheckedBoxes()) {
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Map
if (day != null) {
CurrentItemsStorage.mapModelObjects = new ModelObject[0];
CurrentItemsStorage.mapModelObjects[1] = day;
Intent intent = new Intent(PlanDayScreen.this,
PlanTabsScreen.class);
startActivity(intent);
}
}
});
} else {
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Confirm
new AlertDialog.Builder(PlanDayScreen.this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle(
"Remove " + checkedCount()
+ " things to do")
.setMessage(
"Do you really wish to remove "
+ checkedCount()
+ " things to do from your plan?")
.setPositiveButton("Yes",
new DialogInterface.OnClickListener() {
@Override
public void onClick(
DialogInterface dialog,
int which) {
// Remove
for (int i = 0; i < lista
.getCount(); i++) {
if (checkedBoxes.get(i)) {
// Get checked item
Object ttd = adapter
.getItem(i);
if (ttd instanceof ScheduledThingToDo) {
try {
// Remove it
ScheduledThingToDo tTD = (ScheduledThingToDo) ttd;
Planner.unschedule(
tTD.ttdId,
tTD.time);
} catch (OfflineException ex) {
Toast.makeText(
PlanDayScreen.this,
getResources()
.getString(
R.string.unschedule_error),
Toast.LENGTH_SHORT)
.show();
} catch (InvalidURLException e) {
}
}
}
}
// Reset checkedBoxes and
// BottomLayout
checkedBoxes = new BitSet();
setUpBottomLayout(false);
// Redraws the list
setUpList();
}
}).setNegativeButton("No", null).show();
}
});
}
break;
case R.id.buttonBottom3:
b.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// Update
}
});
break;
}
}
/**
* Sets up the list
*/
private void setUpList() {
lista = (DragNDropListView) findViewById(R.id.listViewAgenda);
new LoadList();
}
/**
* Counts the number of checked boxes
*
* @return the number of checked boxes
*/
private int checkedCount() {
int x = 0;
for (int i = 0; i < checkedBoxes.length(); i++) {
x += checkedBoxes.get(i) ? 1 : 0;
}
return x;
}
/**
* Changes the buttoms on the bottom action bar. If you pass true, you get
* the "delete items" action bar. Else, you get the "add items" action bar.
*
* @param isAnythingMarked
* True if you want to delete items, false if you want to add
* them.
*/
private void setUpBottomLayout(boolean isAnythingMarked) {
ImageButton b1 = (ImageButton) findViewById(R.id.buttonBottom1);
ImageButton b2 = (ImageButton) findViewById(R.id.buttonBottom2);
ImageButton b3 = (ImageButton) findViewById(R.id.buttonBottom3);
b1.setImageDrawable(getResources().getDrawable(
isAnythingMarked ? R.drawable.action_plans
: R.drawable.action_add));
b2.setImageDrawable(getResources().getDrawable(
isAnythingMarked ? R.drawable.action_delete
: R.drawable.action_map));
b3.setImageDrawable(getResources()
.getDrawable(R.drawable.action_reload));
setUpBottomButton(R.id.buttonBottom1);
setUpBottomButton(R.id.buttonBottom2);
setUpBottomButton(R.id.buttonBottom3);
}
private boolean areThereCheckedBoxes() {
for (int i = 0; i < checkedBoxes.length(); i++) {
if (checkedBoxes.get(i)) {
return true;
}
}
return false;
}
public void clickControlRowHandler(View v) {
Intent intent = new Intent(PlanDayScreen.this,
ThingsToDoListScreen.class);
startActivity(intent);
}
/**
* Drop Listener for the DragNDropListView
*/
private DropListener mDropListener = new DropListener() {
public void onDrop(final int from, int to) {
if (to == 0)
to = 1;
// If initial position is the same as final position, do nothing.
if (to != from) {
if (adapter instanceof DragNDropAdapter) {
if (adapter.getItem(from) instanceof ScheduledThingToDo) {
new DropCall(from, to);
((DragNDropAdapter) adapter).onDrop(from, to);
}
}
}
}
};
public OnClickListener onClickSave = new OnClickListener() {
public void onClick(View v) {
try {
if (Login.isRegistered()) {
if (Planner.loadPlan().name == null) {
CurrentItemsStorage.shallGoAfterCreatePlan = PlanDayScreen.class;
if (idDroppedOrDeleted) {
manageListChanges();
}
Intent intent = new Intent(PlanDayScreen.this,
SavePlanScreen.class);
startActivity(intent);
return;
}
} else {
CurrentItemsStorage.currentPlan = Planner.loadPlan();
CurrentItemsStorage.shallGoAfterLogin = PlanDayScreen.class;
Intent intent = new Intent(PlanDayScreen.this,
LoginScreen.class);
startActivity(intent);
}
} catch (OfflineException e) {
Toast.makeText(PlanDayScreen.this,
getResources().getString(R.string.plan_error),
Toast.LENGTH_SHORT).show();
}
if (idDroppedOrDeleted) {
manageListChanges();
}
}
};
/**
* Unschedules every TTD, then schedules it again.
*/
private void manageListChanges() {
for (int i = 0; i < adapter.getCount(); i++) {
Object item = adapter.getItem(i);
if (item instanceof ScheduledThingToDo) {
try {
ScheduledThingToDo scheduled = (ScheduledThingToDo) item;
Planner.unschedule(scheduled.getId(), scheduled.time);
} catch (Exception e) {
e.printStackTrace();
}
}
}
int state = 0;
for (int it = 0; it < adapter.getCount(); it++) {
Object item = adapter.getItem(it);
TimeOfDay tod = TimeOfDay.morning;
if (item instanceof ScheduledThingToDo) {
switch (state) {
case 1:
tod = TimeOfDay.morning;
break;
case 2:
tod = TimeOfDay.afternoon;
break;
case 3:
tod = TimeOfDay.evening;
break;
}
try {
Planner.schedule(((ScheduledThingToDo) item).ttdId,
new ScheduledTime(CurrentItemsStorage.currentDay,
tod));
} catch (OfflineException e) {
Toast.makeText(PlanDayScreen.this, "No connection",
Toast.LENGTH_SHORT).show();
}
} else {
state++;
}
}
}
/**
* RemoveListener for the DragNDropListView
*/
private RemoveListener mRemoveListener = new RemoveListener() {
public void onRemove(int which) {
// ListAdapter adapter = getListAdapter();
if (adapter instanceof DragNDropAdapter) {
((DragNDropAdapter) adapter).onRemove(which);
lista.invalidateViews();
}
}
};
/**
* DragListener for the DragNDropListView
*/
private DragListener mDragListener = new DragListener() {
int backgroundColor = getResources().getColor(R.color.yellow);
int defaultBackgroundColor = getResources().getColor(R.color.blue_bg);
public void onDrag(int x, int y, ListView listView) {
// TODO Auto-generated method stub
}
public void onStartDrag(View itemView) {
itemView.setVisibility(View.INVISIBLE);
itemView.setBackgroundColor(backgroundColor);
ImageView iv = (ImageView) itemView.findViewById(R.id.imageView1);
if (iv != null)
iv.setVisibility(View.INVISIBLE);
}
public void onStopDrag(View itemView) {
itemView.setVisibility(View.VISIBLE);
itemView.setBackgroundColor(defaultBackgroundColor);
ImageView iv = (ImageView) itemView.findViewById(R.id.imageView1);
if (iv != null)
iv.setVisibility(View.VISIBLE);
}
};
private class LoadList extends AsyncTask<Void, Void, Void> {
public LoadList() {
execute();
}
@Override
protected void onPreExecute() {
String[] x = { "Loading..." };
addNewTTD();
ArrayAdapter<String> asdf = new ArrayAdapter<String>(
PlanDayScreen.this, R.layout.add_more, x);
lista.setAdapter(asdf);
}
@Override
protected Void doInBackground(Void... arg0) {
ScheduledThingToDo[] ttds;
try {
try {
// Loads current day
day = Planner.loadDay(CurrentItemsStorage.currentDay);
ttds = day.ttds;
} catch (NullPointerException ex) {
// No current day: Loads today
Day day = Planner.loadDay(Calendar.getInstance());
ttds = day.ttds;
}
} catch (OfflineException e) {
// Offline
Toast.makeText(PlanDayScreen.this,
getResources().getString(R.string.day_error),
Toast.LENGTH_SHORT).show();
ttds = new ScheduledThingToDo[0];
} catch (UnauthorizedException e) {
// Something strange happened
ttds = new ScheduledThingToDo[0];
} catch (Exception e) {
// Something even more strange happened
ttds = new ScheduledThingToDo[0];
}
adapter = new DragNDropAdapter(PlanDayScreen.this,
new int[] { R.layout.dragitemttd }, ttds);
adapter.setOnCheckListener(new OnCheckListener() {
@Override
public void onCheck(boolean isChecked, int position) {
checkedBoxes.set(position, isChecked);
setUpBottomLayout(areThereCheckedBoxes());
}
});
return null;
}
@Override
protected void onPostExecute(Void result) {
lista.setAdapter(adapter);
lista.setDropListener(mDropListener);
lista.setRemoveListener(mRemoveListener);
lista.setDragListener(mDragListener);
}
}
private class DropCall extends AsyncTask<Void, Void, Void> {
private int from, to;
public DropCall(int from, int to) {
this.from = from;
this.to = to;
execute();
lista.invalidateViews();
}
@Override
protected Void doInBackground(Void... arg0) {
changeScheduledTTD(from, to);
return null;
}
/**
* Unschedules a TTD and then re-schedules it in its proper place
*
* @param from
* The position the TTD came from
* @param to
* The position the TTD has been dragged to
*/
protected void changeScheduledTTD(int from, int to) {
ScheduledThingToDo currentTTD;
if (adapter.getItem(to) instanceof ScheduledThingToDo)
currentTTD = (ScheduledThingToDo) adapter.getItem(to);
else
return;
int indexMorning = 0;
int indexAfternoon = 0;
int indexEvening = 0;
Object item = null;
String currentTime = null;
// Gets the indexes for Morning, Afternoon and Evening
for (int i = 0; i < adapter.getCount(); i++) {
item = adapter.getItem(i);
if (item instanceof String) {
currentTime = (String) item;
if (currentTime.equals("MORNING")) {
indexMorning = i;
}
if (currentTime.equals("AFTERNOON")) {
indexAfternoon = i;
}
if (currentTime.equals("EVENING")) {
indexEvening = i;
}
}
}
TimeOfDay tod = null;
if (to >= indexEvening) {
tod = TimeOfDay.evening;
} else if (to >= indexAfternoon) {
tod = TimeOfDay.afternoon;
} else if (to >= indexMorning) {
tod = TimeOfDay.morning;
}
if (!currentTTD.time.getTimeOfDay().equals(tod)) {
try {
Planner.unschedule(currentTTD.ttdId, currentTTD.time);
Planner.schedule(currentTTD.ttdId, new ScheduledTime(
CurrentItemsStorage.currentDay, tod));
} catch (OfflineException e) {
e.printStackTrace();
}
}
}
}
}
推荐答案
你的 mDragListener 是一个成员变量.在初始化 Activity 对象/实例时可能还没有准备好.所以调用Activity的getResource()会失败.
Your mDragListener is a member variable. At the point of initializing the Activity object/instance might not be ready. So calling getResource() of the Activity will fail.
// inner class or normal class ... change scope if needed
private class DragListener {
int color = 0;
public DragListener(Context context) {
color = context.getResource().getColor(R.color.yellow);
}
}
// activity
private DragListener mDragListener;
public void onCreate(...) {
mDragListener = new DragListener(this);
// more code
}
这篇关于android.content.ContextWrapper 处的 NullPointerException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！
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