我有一个片段：
public class TodayVerse extends Fragment
{
TextView textView;
DailyQuranMethods dailyQuranMethods;
public TodayVerse() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState)
{
// Inflate the layout for this fragment
View view = inflater.inflate(R.layout.fragment_today_verse, container, false);
textView = (TextView) view.findViewById(R.id.verse);
// setChapterVerse();
textView.setText(dailyQuranMethods.getVerseToday(dailyQuranMethods.DateToday(),getActivity().getApplicationContext()) + "\nChapter:" + dailyQuranMethods.getChapterTodayName(dailyQuranMethods.DateToday(),getActivity().getApplicationContext()));
return view;
}
}
此片段调用非活动类： dailyQuranMethods ，它使用sharedPrefrences。为此，我必须传递Context作为参数。我通过了：
getActivity（）。getApplicationContext（）
dailyQuranMethods中的方法如下：
public String getVerseToday(String today,Context context){
...
}
在运行应用程序时，我有以下logcat：
06-19 06：07：56.587 9887-9887 /？ E / AndroidRuntime：致命异常： 主要 显示java.lang.NullPointerException 在com.example.shiza.dailyquranverses.TodayVerse.onCreateView（TodayVerse.java:35） 在android.support.v4.app.Fragment.performCreateView（Fragment.java:1789） 在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:955） 在android.support.v4.app.FragmentManagerImpl.moveToState（FragmentManager.java:1138） 在android.support.v4.app.BackStackRecord.run（BackStackRecord.java:740） 在android.support.v4.app.FragmentManagerImpl.execPendingActions（FragmentManager.java:1501） 在android.support.v4.app.FragmentManagerImpl.executePendingTransactions（FragmentManager.java:490） 在android.support.v4.app.FragmentTabHost.onAttachedToWindow（FragmentTabHost.java:283） 在android.view.View.dispatchAttachedToWindow（View.java:9788） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2198） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2206） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2206） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2206） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2206） 在android.view.ViewGroup.dispatchAttachedToWindow（ViewGroup.java:2206） 在android.view.ViewRootImpl.performTraversals（ViewRootImpl.java:971） 在android.view.ViewRootImpl.handleMessage（ViewRootImpl.java:2467） 在android.os.Handler.dispatchMessage（Handler.java:99） 在android.os.Looper.loop（Looper.java:137） 在android.app.ActivityThread.main（ActivityThread.java:4424） at java.lang.reflect.Method.invokeNative（Native Method） 在java.lang.reflect.Method.invoke（Method.java:511） 在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run（ZygoteInit.java:784） 在com.android.internal.os.ZygoteInit.main（ZygoteInit.java:551） 在dalvik.system.NativeStart.main（本地方法）
错误如下：
textView.setText（dailyQuranMethods.getVerseToday（dailyQuranMethods.DateToday（），getActivity（）。getApplicationContext（）） +＆＃34; \ n第章：＆＃34; + dailyQuranMethods.getChapterTodayName（dailyQuranMethods.DateToday（），getActivity（）。getApplicationContext（）））;
看起来，我无法在非活动类中获取Context。我尝试了很多，但没有任何帮助。请帮我解决这个问题。
编辑1：非活动类是：
package com.example.shiza.dailyquranverses;
import android.content.Context;
import android.content.SharedPreferences;
import android.database.MatrixCursor;
import android.preference.PreferenceManager;
import android.provider.BaseColumns;
import android.widget.SimpleCursorAdapter;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Random;
import com.example.shiza.dailyquranverses.TodayChapter;
import android.preference.Preference;
/**
* Created by Shiza on 19-06-2015.
*/
public class DailyQuranMethods {
// generate a random number.
SharedPreferences sharedPreferencesChapter;
SharedPreferences sharedPreferencesVerse;
private static String TODAY_CHAPTER = "TODAY_CHAPTER";
private static String TODAY_VERSE = "TODAY_VERSE";
Context context;
public int GetRandom(int min, int max) {
Random ran = new Random();
return ran.nextInt((max - min) + 1) + min;
}
public void setChapterVerseOfToday(Context context)
{
sharedPreferencesChapter = context.getSharedPreferences(TODAY_CHAPTER, Context.MODE_PRIVATE);
sharedPreferencesVerse = context.getApplicationContext().getSharedPreferences(TODAY_VERSE, Context.MODE_PRIVATE);
SharedPreferences.Editor editor_chapter = sharedPreferencesChapter.edit();
SharedPreferences.Editor editor_verse = sharedPreferencesVerse.edit();
int chapter_no = GetRandom(1, 114);
String chapter_array_name = "chapter_" + chapter_no;
String verse = sharedPreferencesVerse.getString(DateToday(),null);
if ( verse == null )
{
editor_verse.putString(DateToday(), getVerse(context,chapter_array_name));
editor_verse.apply();
}
int chapter_number = sharedPreferencesChapter.getInt(DateToday(),0);
if ( chapter_number == 0 )
{
editor_chapter.putInt(DateToday(),chapter_no);
editor_chapter.apply();
}
}
public String getVerseToday(String today,Context context)
{
sharedPreferencesVerse = context.getSharedPreferences(TODAY_VERSE, Context.MODE_PRIVATE);
return sharedPreferencesVerse.getString(today,"7. The Way of those on whom You have bestowed Your Grace, not (the way) of those who earned Your Anger (such as the Jews), nor of those who went astray (such as the Christians).");
}
public String getVerse(Context context,String chapter_array_name)
{
int id = context.getResources().getIdentifier(chapter_array_name, "array", context.getPackageName());
String[] chapter = context.getResources().getStringArray(id);
int random_verse = GetRandom(1, chapter.length - 1);
return chapter[random_verse];
}
public String[] getChapterTodayContent(String today,Context context)
{
sharedPreferencesChapter = context.getSharedPreferences(TODAY_CHAPTER, Context.MODE_PRIVATE);
int chapter_no = sharedPreferencesChapter.getInt(today, 2);
String chapter_array_name = "chapter_" + chapter_no;
int id = context.getResources().getIdentifier(chapter_array_name, "array", context.getApplicationContext().getPackageName());
return context.getResources().getStringArray(id);
}
public String getChapterTodayName(String today,Context context)
{
sharedPreferencesChapter = context.getApplicationContext().getSharedPreferences(TODAY_CHAPTER,Context.MODE_PRIVATE);
int chapter_no = sharedPreferencesChapter.getInt(today, 0);
String[] chapterName = context.getResources().getStringArray(R.array.chapters);
return chapterName[chapter_no - 1];
}
public String DateToday()
{
Calendar c = Calendar.getInstance();
SimpleDateFormat df = new SimpleDateFormat("ddMMyyyy");
return df.format(c.getTime());
}
// Get quran verses in android
public String[] getQuranVerses(Context context) {
String[] whole_quran = new String[7000];
String[] current_chapter;
String chapterSize = "";
String[] chapter_names;
String chapter_array_name;
int total_verse = 0, verse_in_current_chapter, chapter_number;
chapter_names = context.getResources().getStringArray(R.array.chapters);
for (chapter_number = 1; chapter_number < 114; chapter_number++) {
// Grab each chapter containing verse from Quran
chapter_array_name = "chapter_" + chapter_number;
int id = context.getResources().getIdentifier(chapter_array_name, "array", context.getPackageName());
current_chapter = context.getResources().getStringArray(id);
for (verse_in_current_chapter = 1; verse_in_current_chapter < current_chapter.length - 1; verse_in_current_chapter++) {
whole_quran[total_verse] = current_chapter[verse_in_current_chapter] + "," + chapter_names[chapter_number - 1];
total_verse++;
}
chapterSize += chapter_number + ":" + chapter_names[chapter_number - 1] + ":" + current_chapter.length + "\n";
}
return whole_quran;
}
// public void search()
// {
// // Use search view on the top of your app
//
// search = (SearchView) findViewById(R.id.mySearchView);
// search.setQueryHint("Search Qur'an");
//
//// create a suggestion adapter for dropdown
// final String[] from = new String[] {"cityName"};
// final int[] to = new int[] {android.R.id.text1};
// mAdapter = new SimpleCursorAdapter(this,
// android.R.layout.simple_list_item_2,
// null,
// from,
// to,
// CursorAdapter.FLAG_REGISTER_CONTENT_OBSERVER);
//
// search.setSuggestionsAdapter(mAdapter);
//
// search.setOnSuggestionListener(new SearchView.OnSuggestionListener() {
// @Override
// public boolean onSuggestionClick(int position) {
// // Your code here
//
//
// Cursor theCursor = (Cursor) mAdapter.getCursor();
// String selectedItem = theCursor.getString(position);
//// Toast.makeText(getBaseContext(), " on suggestion click position and item is" + position + selectedItem, Toast.LENGTH_LONG).show();
//
//
// startActivity(new Intent(getBaseContext(), MainActivity.class));
//
// return true;
// }
//
// @Override
// public boolean onSuggestionSelect(int position) {
// // Your code here
//// Toast.makeText(getBaseContext(), " on suggestion select position is" + position, Toast.LENGTH_LONG).show();
//
// startActivity(new Intent(getBaseContext(), MainActivity.class));
//
// return true;
// }
// });
//
// search.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
//
//
// @Override
// public boolean onQueryTextSubmit(String query) {
// startActivity(new Intent(getBaseContext(), MainActivity.class));
//
// return false;
// }
//
// @Override
// public boolean onQueryTextChange(String newText) {
// //
// dailyQuranMethods.populateAdapter(newText,getApplicationContext());
//
// return false;
// }
//
//
// });
//
//
//
// }
public void populateAdapter(String query, Context context, SimpleCursorAdapter mAdapter) {
String[] SUGGESTIONS = getQuranVerses(context);
final MatrixCursor c = new MatrixCursor(new String[]{BaseColumns._ID, "cityName"});
int j = 0;
int k = 0;
if (query.length() > 3) {
k = GetRandom(0, 60);
// Toast.makeText(getApplicationContext(),"K is " + k,Toast.LENGTH_LONG).show();
for (int i = 0; i < 6144; i++) {
if (SUGGESTIONS[i].toLowerCase().contains(query.toLowerCase()) && SUGGESTIONS[i].length() > 0) {
c.addRow(new Object[]{i, SUGGESTIONS[i]});
j++;
if (j > 100) {
break;
}
}
}
if (j == 0) {
c.addRow(new Object[]{0, "No results found."});
}
} else {
c.addRow(new Object[]{0, "Please enter at least 3 characters."});
c.addRow(new Object[]{1, "Please be patient, we have to find in more than 6,000 verses"});
}
mAdapter.changeCursor(c);
}
}
答案 0 :(得分：0)
调用getActivity（）很好，它将解析为Context。你不需要完整的getActivity().getApplicationContext()。这可能会导致问题，因为您告诉Android使用应用程序的上下文而不是当前的Activity。总有一天你会对此表示赞赏。
除此之外，您还需要创建 dailyQuranMethods 的实例。在Java中，除非对象为new，否则始终需要使用static进行创建。这很好记住。
代码示例：
public TodayVerse() {
DailyQuranMethods dailyQuranMethods = new DailyQuranMethods();
}
Android Java好运......