我正在Eclipse中创建一个Android应用程序，而我遇到问题的部分是我尝试使用SQLite数据库中的数据填充ListView。
当我运行应用程序并尝试打开此特定片段时，应用程序崩溃。当我在BreakfastMenuFragment.java的第4行最后一行注释掉行newDB.close()时，它将加载，但不会填充列表视图。
我试图找到问题，但没有运气，任何帮助将不胜感激。
BreakfastMenuFragment.java
package info.androidhive.slidingmenu;
import java.io.IOException;
import java.util.ArrayList;
import android.app.Fragment;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ListView;
public class BreakfastMenuFragment extends Fragment {
public BreakfastMenuFragment(){}
private ArrayList<String> results = new ArrayList<String>();
private String tableName = DBHelper.tableName;
private SQLiteDatabase newDB;
/** Called when the activity is first created.
* @return */
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
View rootView = inflater.inflate(R.layout.menu_layout, container, false);
ListView listView = (ListView) rootView.findViewById(R.id.menuList);
try {
openAndQueryDatabase();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
displayResultList(listView);
return rootView;
}
private void displayResultList(ListView listView) {
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this.getActivity().getApplicationContext(),
android.R.layout.simple_list_item_1, results);
listView.setAdapter(adapter);
}
private void openAndQueryDatabase() throws IOException {
try {
DBHelper dbHelper = new DBHelper(this.getActivity().getApplicationContext());
newDB = dbHelper.getWritableDatabase();
Cursor c = newDB.rawQuery("SELECT itemdesc, itemprice FROM " + tableName + " WHERE menu LIKE 'Breakfast'", null);
if (c != null ) {
if (c.moveToFirst()) {
do {
String itemDesc = c.getString(c.getColumnIndex("itemdesc"));
double itemPrice = c.getDouble(c.getColumnIndex("itemprice"));
results.add("" + itemDesc + " - Price: £"+ itemPrice +"");
}while (c.moveToNext());
}
}
} catch (SQLiteException se ) {
Log.e(getClass().getSimpleName(), "Could not create or Open the database");
} finally {
if (newDB != null)
newDB.execSQL("DELETE FROM " + tableName);
newDB.close();
}
}
}
DBHelper.java
package info.androidhive.slidingmenu;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DBHelper extends SQLiteOpenHelper{
public SQLiteDatabase DB;
public String DBPath;
public static String DBName = "orchard.sqlite";
public static final int version = '1';
public static Context currentContext;
public static String tableName = "menuitems";
public DBHelper(Context context) throws IOException {
super(context, DBName, null, version);
currentContext = context;
DBPath = "/data/data/" + context.getPackageName() + "/databases";
createDatabase();
}
private void createDatabase() throws IOException {
boolean dbExists = checkDbExists();
if (dbExists) {
// do nothing
} else {
// Open your local db as the input stream
String dbname = "orchard.sqlite";
InputStream myInput = currentContext.getAssets().open(dbname);
// Path to the just created empty db
String outFileName = currentContext.getFilesDir().getPath() + dbname;
// Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
// transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0) {
myOutput.write(buffer, 0, length);
}
// Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
}
private boolean checkDbExists() {
SQLiteDatabase checkDB = null;
try {
String myPath = DBPath + DBName;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READONLY);
} catch (SQLiteException e) {
// database does't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null ? true : false;
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
}
}
------------- EDIT --------------------
04-25 03:00:31.485: D/dalvikvm(31817): GC_FOR_ALLOC freed 147K, 15% free 3288K/3828K, paused 20ms, total 20ms
04-25 03:00:31.805: E/SQLiteLog(31817): (1) no such table: menuitems
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): Could not create or Open the database
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): android.database.sqlite.SQLiteException: no such table: menuitems (code 1): , while compiling: SELECT itemdesc, itemprice FROM menuitems WHERE menu LIKE 'Breakfast'
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at info.androidhive.slidingmenu.BreakfastMenuFragment.openAndQueryDatabase(BreakfastMenuFragment.java:72)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at info.androidhive.slidingmenu.BreakfastMenuFragment.onCreateView(BreakfastMenuFragment.java:38)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.Fragment.performCreateView(Fragment.java:1700)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.BackStackRecord.run(BackStackRecord.java:684)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.os.Handler.handleCallback(Handler.java:733)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.os.Handler.dispatchMessage(Handler.java:95)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.os.Looper.loop(Looper.java:136)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at android.app.ActivityThread.main(ActivityThread.java:5021)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at java.lang.reflect.Method.invokeNative(Native Method)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at java.lang.reflect.Method.invoke(Method.java:515)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
04-25 03:00:31.815: E/BreakfastMenuFragment(31817): at dalvik.system.NativeStart.main(Native Method)
04-25 03:05:53.795: E/SQLiteLog(31817): (1) no such table: menuitems
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): Could not create or Open the database
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): android.database.sqlite.SQLiteException: no such table: menuitems (code 1): , while compiling: SELECT itemdesc, itemprice FROM menuitems WHERE menu LIKE 'Breakfast'
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:889)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:500)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at info.androidhive.slidingmenu.BreakfastMenuFragment.openAndQueryDatabase(BreakfastMenuFragment.java:72)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at info.androidhive.slidingmenu.BreakfastMenuFragment.onCreateView(BreakfastMenuFragment.java:38)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.Fragment.performCreateView(Fragment.java:1700)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:890)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1062)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.BackStackRecord.run(BackStackRecord.java:684)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1447)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.FragmentManagerImpl$1.run(FragmentManager.java:443)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.os.Handler.handleCallback(Handler.java:733)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.os.Handler.dispatchMessage(Handler.java:95)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.os.Looper.loop(Looper.java:136)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at android.app.ActivityThread.main(ActivityThread.java:5021)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at java.lang.reflect.Method.invokeNative(Native Method)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at java.lang.reflect.Method.invoke(Method.java:515)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
04-25 03:05:53.795: E/BreakfastMenuFragment(31817): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
ROWLOCKnewDB.close（）;正在执行，无论它是否为null。如果newDB为空，这可能会导致崩溃。
答案 1 :(得分：0)
我的猜测是这行newDB = dbHelper.getWritableDatabase();如果抛出异常。
反过来调用finally块，在那里你错过了＆＃39; {＆＃39;和＆＃39;}＆＃39;对于if声明。
所以你会在NullPointerException上得到无法newDB.close();，因为newDB为null且app会崩溃......
将catch块中的日志更新为Log.e(getClass().getSimpleName(), "Could not create or Open the database", se);并检查LogCat以获取有关出错的更多信息。