我的旧SQLitedatabase没有按照我想要的方式工作，所以我想删除我的旧DBAdapter文件夹和DBHelper文件夹并从头开始创建一个新的数据库，包含2个新表，新列名和一个新的DATABASE_NAME，但在我使用新的字符串和游标将所有内容链接到我的应用程序之后，我收到了一个nullpoint崩溃，我在logcat中收到了这些错误。
更新： 我已经将onCreate参数更改为db并且我解决了无效表错误但现在我有一个表“Players”（MyFirstTable）不存在错误。
更新：新LOGCAT
04-19 19:56:02.781: E/AndroidRuntime(9179): FATAL EXCEPTION: main
04-19 19:56:02.781: E/AndroidRuntime(9179): android.database.sqlite.SQLiteException: no such table: PLAYERS (code 1): , while compiling: SELECT _id, USERNAME FROM PLAYERS
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:882)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:493)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1161)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1032)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1200)
04-19 19:56:02.781: E/AndroidRuntime(9179): at com.fullfrontalgames.numberfighter.DBAdapter.getUsername(DBAdapter.java:143)
04-19 19:56:02.781: E/AndroidRuntime(9179): at com.fullfrontalgames.numberfighter.Findfriends$1.onClick(Findfriends.java:39)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.view.View.performClick(View.java:4106)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.view.View$PerformClick.run(View.java:17052)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.os.Handler.handleCallback(Handler.java:615)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.os.Handler.dispatchMessage(Handler.java:92)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.os.Looper.loop(Looper.java:137)
04-19 19:56:02.781: E/AndroidRuntime(9179): at android.app.ActivityThread.main(ActivityThread.java:5059)
04-19 19:56:02.781: E/AndroidRuntime(9179): at java.lang.reflect.Method.invokeNative(Native Method)
04-19 19:56:02.781: E/AndroidRuntime(9179): at java.lang.reflect.Method.invoke(Method.java:511)
04-19 19:56:02.781: E/AndroidRuntime(9179): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
04-19 19:56:02.781: E/AndroidRuntime(9179): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555)
04-19 19:56:02.781: E/AndroidRuntime(9179): at dalvik.system.NativeStart.main(Native Method)
DBAdapter类
package com.fullfrontalgames.numberfighter;
import android.content.ContentValues;
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.util.Log;
public class DBAdapter {
static final String KEY_ROWID = "_id";
static final String KEY_USERNAME = "USERNAME";
static final String KEY_PASSWORD = "PASSWORD";
static final String KEY_EMAIL = "EMAIL";
static final String KEY_NUMBERINPUT = "NUMBERINPUT";
static final String KEY_SCORE = "SCORE";
static final String KEY_FRIENDS = "FRIENDS";
static final String TAG = "DBAdapter";
static final String DATABASE_NAME = "NFDatabase";
static final String DATABASE_TABLE1 = "PLAYERS";
static final String DATABASE_TABLE2 = "FRIENDSLIST";
static final int DATABASE_VERSION = 1;
static final String DATABASE_CREATE_TABLE1 = "create table PLAYERS (_id integer primary key autoincrement,"
+ "USERNAME text not null,PASSWORD text not null,EMAIL text not null,NUMBERINPUT text not null,,SCORE text not null;";
static final String DATBASE_CREATE_TABLE2 = "create table FRIENDSLIST (_id integer primary key autoincrement,"
+ "FRIENDS text not null,USERNAME text not null,NUMBERINPUT text not null,SCORE text not null;";
final Context context;
DatabaseHelper DBHelper;
static SQLiteDatabase db;
public DBAdapter(Context ctx) {
this.context = ctx;
DBHelper = new DatabaseHelper(context);
}
private static class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper(Context context) {
// TODO Auto-generated constructor stub
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
// TODO Auto-generated method stub
try {
db.execSQL(DATABASE_CREATE_TABLE1);
db.execSQL(DATABASE_CREATE_TABLE2);
} catch (SQLException e) {
e.printStackTrace();
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub
Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion
+ ", which will destroy all old data");
db.execSQL("DROP TABLE IF EXISTS PLAYERS,FRIENDSLIST");
onCreate(db);
}
}
public DBAdapter open() throws SQLiteException {
db = DBHelper.getWritableDatabase();
return this;
}
public void close() {
DBHelper.close();
}
// PLAYERS TABLE CRUD
public void insertPlayer(String Username, String Password, String Email) {
ContentValues initialValues = new ContentValues();
initialValues.put("USERNAME", Username);
initialValues.put("PASSWORD", Password);
initialValues.put("EMAIL", Email);
}
public boolean deletePlayer(String username) {
return db.delete("PLAYERS", KEY_ROWID + " = " + "_id", null) > 0;
}
public Cursor getAllPlayers() {
return db.query(null, new String[] {
"_id", "USERNAME", "PASSWORD", "EMAIL"
}, null, null, null, null, null, null);
}
public String getData() {
String[] columns = new String[] {
"_id", "USERNAME", "PASSWORD"
};
Cursor mCursor = db.query("PLAYERS", columns, null, null, null, null, null);
String result = "";
int iRow = mCursor.getColumnIndex(KEY_ROWID);
int iName = mCursor.getColumnIndex(KEY_USERNAME);
for (mCursor.moveToFirst(); !mCursor.isAfterLast(); mCursor.moveToNext()) {
result = mCursor.getString(iRow) + " " + mCursor.getString(iName) + "/n";
}
return result;
}
public Cursor getPlayer(long rowid) throws SQLException {
Cursor mCursor = db.query(true, "PLAYERS", new String[] {
"_id", "USERNAME"
}, KEY_ROWID + " = " + "_id", null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public String getUsername(String username) {
// TODO Auto-generated method stub
String[] columns = new String[] {
"_id", "USERNAME"
};
Cursor mCursor = db.query("PLAYERS", columns, null, null, null, null, null);
String result = "";
int iRow = mCursor.getColumnIndex(KEY_ROWID);
int iName = mCursor.getColumnIndex(KEY_USERNAME);
for (mCursor.moveToFirst(); !mCursor.isAfterLast(); mCursor.moveToNext()) {
result = mCursor.getString(iRow) + " " + mCursor.getString(iName) + "/n";
}
return result;
}
public String getSinlgeEntry(String Username) {
Cursor cursor = db.query("PLAYERS", null, " USERNAME=?", new String[] {
Username
}, null, null, null);
if (cursor.getCount() < 1) // UserName Not Exist
{
cursor.close();
return "NOT EXIST";
}
cursor.moveToFirst();
String password = cursor.getString(cursor.getColumnIndex("PASSWORD"));
cursor.close();
return password;
}
public boolean updatePlayer(long _id, String Username, String Password, String Email) {
ContentValues args = new ContentValues();
args.put("USERNAME", Username);
args.put("PASSWORD", Password);
args.put("EMAIL", Email);
return db.update("PLAYERS", args, KEY_ROWID + " = " + _id, null) > 0;
}
// FRIENDS TABLE CRUD
public void insertFriend(String Friend) {
ContentValues initialValues = new ContentValues();
initialValues.put("FRIENDS", Friend);
db.insert("FRIENDSLIST", null, null);
}
public boolean deleteFriend(String deletedfriend) {
return db.delete("FRIENDSLIST", KEY_ROWID + " = " + "_id", null) > 0;
}
public Cursor getAllFriends() {
return db.query(null, new String[] {
"_id", "FRIENDS"
}, null, null, null, null, null, null);
}
public Cursor getFriend(long rowid) throws SQLException {
Cursor mCursor = db.query(true, "FRIENDSLIST", new String[] {
"_id", "FRIENDS"
}, KEY_ROWID + " = " + "_id", null, null, null, null, null);
if (mCursor != null) {
mCursor.moveToFirst();
}
return mCursor;
}
public boolean updateFriend(long _id, String Friends) {
ContentValues args = new ContentValues();
args.put("FRIENDS", Friends);
return db.update("FRIENDSLIST", args, KEY_ROWID + " = " + _id, null) > 0;
}
}
答案 0 :(得分：1)
在这里，你没有像其他方法那样命名你的方法参数db，所以我猜它是静态变量DBAdapter.db。
public void onCreate(SQLiteDatabase arg0) {
// TODO Auto-generated method stub
try {
db.execSQL(DATABASE_CREATE_TABLE1);
db.execSQL(DATBASE_CREATE_TABLE2);
} catch (SQLException e) {
e.printStackTrace();
}
}
尝试将arg0更改为db。