Sqlite不会读取多个游标
我是Android新手。我有应用程序，它与sqlite专家数据库连接。我在assets文件夹中添加了我的数据库。我的问题是第一个光标是读取但程序从不读取第二个光标。
我正在看这个问题，但我找不到答案 problem about sqlite database, no such table:
package com.qozix.data;
import java.sql.Date;
import java.util.ArrayList;
import java.util.List;
import com.qozix.sqlite.DataBaseHelper;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
public class ClassRepository {
private List<ClassData> classDataList=new ArrayList<ClassData>();
private List<EventData> EventDataList=new ArrayList<EventData>();
private Context myContext;
private DataBaseHelper dataBaseHelper;
public ClassRepository(Context context) {
myContext=context;
dataBaseHelper=new DataBaseHelper(context);
loadData();
loadData2();
}
public void loadData(){
try {
dataBaseHelper.openDataBase();
SQLiteDatabase database=dataBaseHelper.getMyDataBase();
String[] columns={"_id","name","x","y"};
Cursor cursor=database.query("classroom", columns,null , null, null, null, null, null);
while(cursor.moveToNext()){
int _id=cursor.getInt(cursor.getColumnIndexOrThrow("_id"));
String name=cursor.getString(cursor.getColumnIndexOrThrow("name"));
String codename= name;
int x=cursor.getInt(cursor.getColumnIndexOrThrow("x"));
int y=cursor.getInt(cursor.getColumnIndexOrThrow("y"));
String message=""+_id+" "+name+" "+x+" "+y;
Log.i("[InDoorMap]", message);
classDataList.add(new ClassData(codename,name,x,y));
}
} catch (Exception e) {
Log.e("[InDoorMap]", "Database exception first cursor ",e);
}
}
public void loadData2(){
try {
dataBaseHelper.openDataBase();
SQLiteDatabase database=dataBaseHelper.getMyDataBase();
String[] column2={"_id","description","hour","name"};
Cursor cursor2=database.query("events", column2,null , null, null, null, null, null);
while(cursor2.moveToNext()){
int _id1=cursor2.getInt(cursor2.getColumnIndexOrThrow("_id"));
String description=cursor2.getString(cursor2.getColumnIndexOrThrow("description"));
String hour = cursor2.getString(cursor2.getColumnIndexOrThrow("hour"));
String nameevent = cursor2.getString(cursor2.getColumnIndexOrThrow("name"));
String message2=""+_id1+" "+description+" "+hour+" "+nameevent;
Log.i("[event]", message2);
System.out.println(message2);
EventDataList.add(new EventData(nameevent,hour,description));
Log.e("[InDoorMap]", "Evente girmedi");
}
} catch (Exception e) {
Log.e("[InDoorMap]", "Database exception secon cursor ",e);
}
}
}
采取资产文件夹
�StableeventseventsCREATETABLE[events]（
这是log cat
05-06 00:12:33.598: (29244): Database already exists
05-06 00:12:33.598: (29244): Database opened.
05-06 00:12:44.910: (29244): 1 PigastroCafe 1336 1688 // it read other table
05-06 00:12:44.910: (29244): 2 Pigastro 540 344
05-06 00:12:44.910: E/SQLiteLog(29244): (1) no such table: events
05-06 00:12:44.926: (29244): Database exception secon cursor
05-06 00:12:44.926: (29244): android.database.sqlite.SQLiteException: no such table: events (code 1): , while compiling: SELECT _id, description, hour, name FROM events
05-06 00:12:44.926: (29244): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
05-06 00:12:44.926: (29244): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1013)
这是我的databasehelper类在这个页面上的连接。我真的没有发现问题：（（
package com.qozix.sqlite;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteQueryBuilder;
import android.util.Log;
public class DataBaseHelper extends SQLiteOpenHelper{
//The Android's default system path of your application database.
private static String DB_NAME = "KhasIndoor6";
private SQLiteDatabase myDataBase;
private final Context myContext;
/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 3);
this.myContext = context;
}
public SQLiteDatabase getMyDataBase() {
return myDataBase;
}
/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException{
boolean dbExist = checkDataBase();
if(dbExist){
Log.i("[InDoorMap]", "Database already exists ");
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
Log.i("[InDoorMap]", "Database created ");
try {
copyDataBase();
Log.i("[InDoorMap]", "Database copied ");
} catch (IOException e) {
Log.e("[InDoorMap]", "Database exception ",e);
throw new Error("Error copying database");
}
}
}
/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){
SQLiteDatabase checkDB = null;
try{
String myPath = myContext.getFilesDir().getPath() +"/"+ DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
myDataBase=checkDB;
}catch(SQLiteException e){
//database does't exist yet.
}
if(checkDB != null){
checkDB.close();
}
return checkDB != null ? true : false;
}
/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = myContext.getFilesDir().getPath()+"/" + DB_NAME;
//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();
File outFile=new File(outFileName);
Log.i("[InDoorMap]", "Output file "+outFile.getAbsolutePath()+" "+outFile.exists()+" "+outFile.length());
}
public void openDataBase() throws SQLException{
//Open the database
String myPath = myContext.getFilesDir().getPath()+"/" + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close() {
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
1 个答案:
答案 0 :(得分：0)
操作完成后关闭光标和数据库句柄。更改您的查询，如下面的代码所示。 使用以下代码。
package com.qozix.data;
import java.sql.Date;
import java.util.ArrayList;
import java.util.List;
import com.qozix.sqlite.DataBaseHelper;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
public class ClassRepository {
private List<ClassData> classDataList=new ArrayList<ClassData>();
private List<EventData> EventDataList=new ArrayList<EventData>();
private Context myContext;
private DataBaseHelper dataBaseHelper;
public ClassRepository(Context context) {
myContext=context;
dataBaseHelper=new DataBaseHelper(context);
loadData();
loadData2();
}
public void loadData(){
try {
dataBaseHelper.openDataBase();
SQLiteDatabase database=dataBaseHelper.getMyDataBase();
String[] columns={"_id","name","x","y"};
Cursor cursor=database.rawQuery("select _id,name,x,y from classroom",null);
while(cursor.moveToNext()){
int _id=cursor.getInt(cursor.getColumnIndexOrThrow("_id"));
String name=cursor.getString(cursor.getColumnIndexOrThrow("name"));
String codename= name;
int x=cursor.getInt(cursor.getColumnIndexOrThrow("x"));
int y=cursor.getInt(cursor.getColumnIndexOrThrow("y"));
String message=""+_id+" "+name+" "+x+" "+y;
Log.i("[InDoorMap]", message);
classDataList.add(new ClassData(codename,name,x,y));
}
} catch (Exception e) {
Log.e("[InDoorMap]", "Database exception first cursor ",e);
}
dataBaseHelper.close();
cursor.close();
}
public void loadData2(){
try {
dataBaseHelper.openDataBase();
SQLiteDatabase database=dataBaseHelper.getMyDataBase();
String[] column2={"_id","description","hour","name"};
Cursor cursor=database.rawQuery("select _id,description,hour,name from events",null);
while(cursor2.moveToNext()){
int _id1=cursor2.getInt(cursor2.getColumnIndexOrThrow("_id"));
String description=cursor2.getString(cursor2.getColumnIndexOrThrow("description"));
String hour = cursor2.getString(cursor2.getColumnIndexOrThrow("hour"));
String nameevent = cursor2.getString(cursor2.getColumnIndexOrThrow("name"));
String message2=""+_id1+" "+description+" "+hour+" "+nameevent;
Log.i("[event]", message2);
System.out.println(message2);
EventDataList.add(new EventData(nameevent,hour,description));
Log.e("[InDoorMap]", "Evente girmedi");
}
} catch (Exception e) {
Log.e("[InDoorMap]", "Database exception secon cursor ",e);
}
dataBaseHelper.close();
cursor2.close();
}
}
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