java - 新建的 SQLitedatabase 表不存在

Question

我的旧 SQLite 数据库没有按照我想要的方式工作，所以我想删除旧的 DBAdapter 文件夹和 DBHelper 文件夹，并从头开始创建一个新数据库，其中包含 2 个新表、新列名和一个新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后，我遇到了空点崩溃，并且在我的 logcat 中收到了这些错误。

更新:我已将 onCreate 参数更改为 db，并解决了无效表错误，但现在我有一个表“Players”(MyFirstTable) 不存在错误。

更新:新的 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;
    }

}

Answer 1

在这里，您没有像其他方法一样命名您的方法参数db，所以我猜它正在隐藏静态变量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。