用NPE片段活动 [英] Fragment Activity with a NPE
问题描述
您好我想创建我的第一个片段活动和日Thnx从纳塔利(续从这个线程)一的帮助>。我convertied的正常工作为我做了它这一点上fragmentand一个类,但现在我有臭名昭著的NPE,我不能决心。
它看起来像从我的名单片段类,但我不能弄明白。我敢肯定它的一个简单的办法。(?),我也换成硬code一些变量,使其更容易一点点地运行。
下面是我的LogCat中和副本活动。日Thnx为您的帮助提前!!
编辑: 正确的日志文件:的
LogCat中:
10月2日至3日:21:14.410:E / AndroidRuntime(29792):致命异常:主要
10月2日至3日:21:14.410:E / AndroidRuntime(29792):了java.lang.RuntimeException:无法启动活动ComponentInfo {com.andaero.test / com.andaero.test.fragments.MainActivity}:显示java.lang.NullPointerException
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread.access $ 500(ActivityThread.java:122)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:1024)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.os.Handler.dispatchMessage(Handler.java:99)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.os.Looper.loop(Looper.java:132)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread.main(ActivityThread.java:4123)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在java.lang.reflect.Method.invokeNative(本机方法)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在java.lang.reflect.Method.invoke(Method.java:491)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:841)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在dalvik.system.NativeStart.main(本机方法)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):致:显示java.lang.NullPointerException
。十月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteProgram<&初始化GT;(SQLiteProgram.java:99)
。十月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteProgram<&初始化GT;(SQLiteProgram.java:94)
。十月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteQuery<&初始化GT;(SQLiteQuery.java:46)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1539)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1508)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在com.andaero.test.fragments.ListFragment.loadQuery(ListFragment.java:72)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在com.andaero.test.fragments.ListFragment.onActivityCreated(ListFragment.java:60)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.FragmentManagerImpl.moveToState(FragmentManager.java:795)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.FragmentManagerImpl.moveToState(FragmentManager.java:977)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.FragmentManagerImpl.moveToState(FragmentManager.java:960)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1674)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.Activity.performCreate(Activity.java:4400)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
10月2日至3日:21:14.410:E / AndroidRuntime(29792):... 11个
MainActivity类别:
公共类MainActivity延伸活动{ / **当第一次创建活动调用。 * / @覆盖
公共无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.main);
}该ListFragment类:
公共类ListFragment扩展android.app.ListFragment { 布尔mDualPane;
INT mCurCheckPosition = 0;
保护的TextView activityTitle; 布尔mExternalStorageAvailable = FALSE;
布尔mExternalStorageWriteable = FALSE; 字符串extStorageDirectory = Environment.getExternalStorageDirectory()
的ToString();
文件DBFILE =新的文件(extStorageDirectory +/myApp/dB/myApp.db);
SQLiteDatabase DB = SQLiteDatabase.openOrCreateDatabase(DBFILE,NULL); 私有静态最后弦乐QUERY_KEY =SELECT * FROM Regulatory_List
私有静态最后弦乐QUERY_ORDER =ASC; 私人视图布局; @覆盖
公共查看onCreateView(LayoutInflater充气器,容器的ViewGroup,
捆绑savedInstanceState){
布局= inflater.inflate(R.layout.listview,NULL);
返回布局; } @覆盖
公共无效onActivityCreated(捆绑savedInstanceState){
super.onActivityCreated(savedInstanceState); 捆绑额外= getActivity()getIntent()getExtras()。 串Q = NULL;
如果(临时演员!= NULL){
Q = extras.getString(QUERY_KEY);
}
loadquery子(Q); } 公共无效loadquery子(串Q){ 如果(Environment.getExternalStorageState()。等于(
Environment.MEDIA_MOUNTED)){ 串QO = getActivity()getIntent()getStringExtra(QUERY_ORDER)。。 光标C = db.rawQuery(Q +ORDER BY`_id`+ QO,NULL);
setListAdapter(新QueryAdapter(getActivity(),C));
db.close(); }其他{
Alerts.sdCardMissing(getActivity());
}
} 公共类QueryAdapter扩展的CursorAdapter { 公共QueryAdapter(上下文的背景下,光标C){
超(背景下,C);
LayoutInflater.from(上下文);
} @覆盖
公共无效bindView(视图V,上下文的背景下,最终的光标C){ INT tvLabel = c.getColumnIndexOrThrow(标签);
字符串标签= c.getString(tvLabel);
最终的TextView labelTxt =(TextView中)v.findViewById(R.id.label); 如果(labelTxt!= NULL){
labelTxt.setText((+标签+));
} INT tvTitle = c.getColumnIndexOrThrow(标题);
最后弦乐标题= c.getString(tvTitle);
TextView的titleTxt =(TextView中)v.findViewById(R.id.listTitle); 如果(titleTxt!= NULL){
titleTxt.setText(职称);
} INT tvDescription = c.getColumnIndexOrThrow(说明);
字符串描述= c.getString(tvDescription);
TextView的descriptionTxt =(TextView中)v.findViewById(R.id.caption); 如果(descriptionTxt!= NULL){
descriptionTxt.setText(介绍);
} INT tvDate = c.getColumnIndexOrThrow(日期);
字符串日期= c.getString(tvDate);
TextView的dateTxt =(TextView中)v.findViewById(R.id.dateAdded); 如果(dateTxt!= NULL){
dateTxt.setText(日期);
} INT tvGoto = c.getColumnIndexOrThrow(gotoURL);
最后弦乐gotoURL = c.getString(tvGoto);
TextView的gotoTxt =(TextView中)v.findViewById(R.id.dummy); 如果(gotoTxt!= NULL){
gotoTxt.setText(gotoURL);
} gotoTxt.setVisibility(View.GONE);
v.setTag(gotoURL); 最终的ListView LV = getListView();
lv.setEnabled(真);
lv.setClickable(真); lv.setOnItemClickListener(新OnItemClickListener(){ 公共无效onItemClick(适配器视图<>为arg0,视图V,INT ARG2,
长ARG3){ 字符串URL =;
URL =(字符串)v.getTag(); INT NI = c.getColumnIndexOrThrow(意图);
字符串意图= c.getString(NI);
类<> myIntent = NULL;
尝试{
myIntent =的Class.forName(com.andaero.test.fragments
+意向);
}赶上(ClassNotFoundException的E){
// TODO自动生成catch块
e.printStackTrace();
} INT tvTitle = c.getColumnIndexOrThrow(标题);
字符串title = c.getString(tvTitle); INT tvLabel = c.getColumnIndexOrThrow(标签);
字符串标签= c.getString(tvLabel); 字符串queryKey =SELECT * FROM+标签;
c.close();
db.close(); 意图I =新意图();
i.putExtra(QUERY_KEY,queryKey);
i.putExtra(KEY_URL,URL);
i.putExtra(KEY_SUBTITLE称号);
i.putExtra(KEY_LABEL标签);
i.putExtra(KEY_INTENT,意图);
i.putExtra(QUERY_ORDER,ASC);
i.putExtra(KEY_YPOS,0.0);
startActivity(ⅰ);
}
});
} @覆盖
公共查看NewView的(上下文的背景下,光标光标的ViewGroup父){
最后的视图V = LayoutInflater.from(上下文).inflate(
R.layout.list_item,父母,假);
返回伏;
}
} }
产生的原因:java.lang.IllegalArgumentException异常:列'_id'不存在
意味着你没有一个叫_id列在表中你
请参阅此链接。
适配器,从游标到ListView控件公开数据,光标必须包含一个名为列_id或本级将无法正常工作。
编辑:
貌似查询可能是无效的。我想你想要的是:
光标C = db.rawQuery(QUERY_KEY +ORDER BY`_id`+ QUERY_ORDER,NULL);
如果您仍然有问题,添加更多的信息登录:
Log.e(查询,Q +ORDER BY`_id`+ QO);
编辑:
为什么要这么做 Q = extras.getString(QUERY_KEY);
是查询是从另一个活动通行证?看起来像你想 loadquery子(QUERY_KEY);
Hi I'm trying to create my first fragment activities and thnx for the help from Natali (Cont from this thread). I convertied a class that worked fine into a fragmentand I've made it to this point but now I have the infamous NPE that I cant resolve.
It looks like its from my list-fragment class but I cant figure it out. I'm sure its an easy fix..(?) and I also replaced some variables with hard-code to make it a little easier to run.
Below is a copy of my LogCat and the activities. Thnx for your help in advance!!
EDIT: The correct log file: LogCat:
02-03 10:21:14.410: E/AndroidRuntime(29792): FATAL EXCEPTION: main
02-03 10:21:14.410: E/AndroidRuntime(29792): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.andaero.test/com.andaero.test.fragments.MainActivity}: java.lang.NullPointerException
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread.access$500(ActivityThread.java:122)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.os.Handler.dispatchMessage(Handler.java:99)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.os.Looper.loop(Looper.java:132)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread.main(ActivityThread.java:4123)
02-03 10:21:14.410: E/AndroidRuntime(29792): at java.lang.reflect.Method.invokeNative(Native Method)
02-03 10:21:14.410: E/AndroidRuntime(29792): at java.lang.reflect.Method.invoke(Method.java:491)
02-03 10:21:14.410: E/AndroidRuntime(29792): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
02-03 10:21:14.410: E/AndroidRuntime(29792): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
02-03 10:21:14.410: E/AndroidRuntime(29792): at dalvik.system.NativeStart.main(Native Method)
02-03 10:21:14.410: E/AndroidRuntime(29792): Caused by: java.lang.NullPointerException
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:99)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:94)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:46)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:47)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1539)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1508)
02-03 10:21:14.410: E/AndroidRuntime(29792): at com.andaero.test.fragments.ListFragment.loadQuery(ListFragment.java:72)
02-03 10:21:14.410: E/AndroidRuntime(29792): at com.andaero.test.fragments.ListFragment.onActivityCreated(ListFragment.java:60)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:795)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:977)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:960)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.FragmentManagerImpl.dispatchActivityCreated(FragmentManager.java:1674)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.Activity.performCreate(Activity.java:4400)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
02-03 10:21:14.410: E/AndroidRuntime(29792): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
02-03 10:21:14.410: E/AndroidRuntime(29792): ... 11 more
The MainActivity Class:
public class MainActivity extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
The ListFragment Class:
public class ListFragment extends android.app.ListFragment {
boolean mDualPane;
int mCurCheckPosition = 0;
protected TextView activityTitle;
boolean mExternalStorageAvailable = false;
boolean mExternalStorageWriteable = false;
String extStorageDirectory = Environment.getExternalStorageDirectory()
.toString();
File dbfile = new File(extStorageDirectory + "/myApp/dB/myApp.db");
SQLiteDatabase db = SQLiteDatabase.openOrCreateDatabase(dbfile, null);
private static final String QUERY_KEY = "SELECT * FROM Regulatory_List";
private static final String QUERY_ORDER = "ASC";
private View layout;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
layout = inflater.inflate(R.layout.listview, null);
return layout;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Bundle extras = getActivity().getIntent().getExtras();
String q = null;
if (extras != null) {
q = extras.getString(QUERY_KEY);
}
loadQuery(q);
}
public void loadQuery(String q) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {
String qO = getActivity().getIntent().getStringExtra("QUERY_ORDER");
Cursor c = db.rawQuery(q + " ORDER BY `_id` " + qO, null);
setListAdapter(new QueryAdapter(getActivity(), c));
db.close();
} else {
Alerts.sdCardMissing(getActivity());
}
}
public class QueryAdapter extends CursorAdapter {
public QueryAdapter(Context context, Cursor c) {
super(context, c);
LayoutInflater.from(context);
}
@Override
public void bindView(View v, Context context, final Cursor c) {
int tvLabel = c.getColumnIndexOrThrow("label");
String label = c.getString(tvLabel);
final TextView labelTxt = (TextView) v.findViewById(R.id.label);
if (labelTxt != null) {
labelTxt.setText("(" + label + ")");
}
int tvTitle = c.getColumnIndexOrThrow("title");
final String title = c.getString(tvTitle);
TextView titleTxt = (TextView) v.findViewById(R.id.listTitle);
if (titleTxt != null) {
titleTxt.setText(title);
}
int tvDescription = c.getColumnIndexOrThrow("description");
String description = c.getString(tvDescription);
TextView descriptionTxt = (TextView) v.findViewById(R.id.caption);
if (descriptionTxt != null) {
descriptionTxt.setText(description);
}
int tvDate = c.getColumnIndexOrThrow("date");
String date = c.getString(tvDate);
TextView dateTxt = (TextView) v.findViewById(R.id.dateAdded);
if (dateTxt != null) {
dateTxt.setText(date);
}
int tvGoto = c.getColumnIndexOrThrow("gotoURL");
final String gotoURL = c.getString(tvGoto);
TextView gotoTxt = (TextView) v.findViewById(R.id.dummy);
if (gotoTxt != null) {
gotoTxt.setText(gotoURL);
}
gotoTxt.setVisibility(View.GONE);
v.setTag(gotoURL);
final ListView lv = getListView();
lv.setEnabled(true);
lv.setClickable(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> arg0, View v, int arg2,
long arg3) {
String url = "";
url = (String) v.getTag();
int nI = c.getColumnIndexOrThrow("intent");
String intent = c.getString(nI);
Class<?> myIntent = null;
try {
myIntent = Class.forName("com.andaero.test.fragments"
+ intent);
} catch (ClassNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
int tvTitle = c.getColumnIndexOrThrow("title");
String title = c.getString(tvTitle);
int tvLabel = c.getColumnIndexOrThrow("label");
String label = c.getString(tvLabel);
String queryKey = "SELECT * FROM " + label;
c.close();
db.close();
Intent i = new Intent();
i.putExtra("QUERY_KEY", queryKey);
i.putExtra("KEY_URL", url);
i.putExtra("KEY_SUBTITLE", title);
i.putExtra("KEY_LABEL", label);
i.putExtra("KEY_INTENT", intent);
i.putExtra("QUERY_ORDER", "ASC");
i.putExtra("KEY_YPOS", "0.0");
startActivity(i);
}
});
}
@Override
public View newView(Context context, Cursor cursor, ViewGroup parent) {
final View v = LayoutInflater.from(context).inflate(
R.layout.list_item, parent, false);
return v;
}
}
}
Caused by: java.lang.IllegalArgumentException: column '_id' does not exist
Means you don't have a column named _id in you table.
See this link.
"Adapter that exposes data from a Cursor to a ListView widget. The Cursor must include a column named "_id" or this class will not work."
EDIT:
Looks like the query may be invalid. I think what you want is:
Cursor c = db.rawQuery(QUERY_KEY + " ORDER BY `_id` " + QUERY_ORDER, null);
If you still have issues add more info to log:
Log.e("QUERY", q + " ORDER BY `_id` " + qO);
EDIT:
Why are you doing this q = extras.getString(QUERY_KEY);
Is the query being pass from another activity? Seem like you want loadQuery(QUERY_KEY);
这篇关于用NPE片段活动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!