java - 拒绝对先前失败的类 java.lang.Class 重新初始化android studio sqlite 数据库

Question

`package com.example.wheresnapped;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class DataManager {

    // the actual apps database
    private SQLiteDatabase db;

    // public static final string for each row of the table that we need
    // to refer both inside and outside this class

    public static final String TABLE_ROW_ID = "_id";
    public static final String TABLE_ROW_TITLE = "image_title";
    public static final String TABLE_ROW_URI = "image_uri";

    // private ones that we need to refer to just from within this class

    private static final String DB_NAME = "w_snap_db";
    private static final int DB_VERSION = 1;
    private static final String TABLE_PHOTOS = "ws_table_photos";
    private static final String TABLE_TAGS = "ws_table_tags";
    private static final String TABLE_ROW_TAG1 = "tag1";
    private static final String TABLE_ROW_TAG2 = "tag2";
    private static final String TABLE_ROW_TAG3 = "tag3";
    public static final String TABLE_ROW_TAG = "tag";      // for the tags table

    public DataManager(Context context){
        CustomSQLITEOpenHelper helper = new CustomSQLITEOpenHelper(context);

        // get a writable database
        db = helper.getWritableDatabase();
    }

    public void addPhoto(Photo photo){
        // add all the details to the photos table
        String query = "INSERT INTO " + TABLE_PHOTOS +" (" +
                TABLE_ROW_TITLE + ", " +
                TABLE_ROW_URI + ", " +
                TABLE_ROW_TAG1 + ", " +
                TABLE_ROW_TAG2 + ", " +
                TABLE_ROW_TAG3 + ") " +
                "VALUES (" +
                "'" + photo.getTitle() +"'" + ", " +
                "'" + photo.getStorageLocation() + "'" + ", " +
                "'" + photo.getTag1() + "'" + ", " +
                "'" + photo.getTag2() + "'" + ", " +
                "'" + photo.getTag3() + "'" + ", " +
                ");";

        Log.i("addPhoto()", query);
        db.execSQL(query);

        // add any new tags to the tags table

        query = "INSERT INTO " + TABLE_TAGS + "(" +
                TABLE_ROW_TAG + ") " +
                "SELECT '" + photo.getTag1() + "' " +
                "WHERE NOT EXISTS (SELECT 1 FROM )" +
                TABLE_TAGS +
                " WHERE " + TABLE_ROW_TAG + " = " +
                "'" + photo.getTag1() +"');";

        db.execSQL(query);

        query = "INSERT INTO " + TABLE_TAGS + "(" +
                TABLE_ROW_TAG + ") " +
                "SELECT '" + photo.getTag2() + "' " +
                "WHERE NOT EXISTS (SELECT 1 FROM )" +
                TABLE_TAGS +
                " WHERE " + TABLE_ROW_TAG + " = " +
                "'" + photo.getTag2() +"');";

        db.execSQL(query);

        query = "INSERT INTO " + TABLE_TAGS + "(" +
                TABLE_ROW_TAG + ") " +
                "SELECT '" + photo.getTag3() + "' " +
                "WHERE NOT EXISTS (SELECT 1 FROM )" +
                TABLE_TAGS +
                " WHERE " + TABLE_ROW_TAG + " = " +
                "'" + photo.getTag3() +"');";

        db.execSQL(query);

    }

    public Cursor getTitles(){
        Cursor c = db.rawQuery("SELECT " + TABLE_ROW_ID + ", " +
                TABLE_ROW_TITLE + "from " + TABLE_PHOTOS, null);

        c.moveToFirst();
        return c;
    }

    public Cursor getTitlesWithTag(String tag){
        Cursor c = db.rawQuery("SELECT " + TABLE_ROW_ID + ", " +
                TABLE_ROW_TITLE + " from " +
                TABLE_PHOTOS + " WHERE " +
                TABLE_ROW_TAG1 + " = '" + tag + "' or " +
                TABLE_ROW_TAG2 + " = '" + tag + "' or " +
                TABLE_ROW_TAG3 + " = '" + tag + "';", null);

        c.moveToFirst();
        return c;
    }

    public Cursor getPhoto(int id){

        Cursor c = db.rawQuery("SELECT * from " +
                TABLE_PHOTOS +
                " WHERE " +
                TABLE_ROW_ID + " = " + id, null);

        c.moveToFirst();
        return c;
    }

    // returns all the tags for our fragment class
    public Cursor getTags(){
        Cursor c = db.rawQuery("SELECT " + TABLE_ROW_ID + ", " +
                TABLE_ROW_TAG + " from " + TABLE_TAGS, null);

        c.moveToFirst();
        return c;
    }

    // class is created when our DataManager is initialized
    private class CustomSQLITEOpenHelper extends SQLiteOpenHelper {

        public CustomSQLITEOpenHelper(Context context){
            super(context, DB_NAME, null, DB_VERSION);
        }

        // only runs the first time the database is created
        @Override
        public void onCreate(SQLiteDatabase db) {

            // create table for photos and all their details
            String newTableQueryString = "create table "
                    + TABLE_PHOTOS + " ("
                    +TABLE_ROW_ID
                    + " integer primary key autoincrement not null,"
                    + TABLE_ROW_TITLE
                    + " text not null,"
                    + TABLE_ROW_URI
                    + " text not null,"
                    + TABLE_ROW_TAG1
                    + " text not null,"
                    + TABLE_ROW_TAG2
                    + " text not null,"
                    + TABLE_ROW_TAG3
                    + " text not null" + ");";

            db.execSQL(newTableQueryString);

            // create a separate table for tags
            newTableQueryString = "create table "
                    + TABLE_TAGS + " ("
                    + TABLE_ROW_ID
                    + " integer primary key autoincrement not null,"
                    + TABLE_ROW_TAG
                    + " text not null" + ");";

            db.execSQL(newTableQueryString);
        }

        // method only runs when we increment db version
        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        }
    }
}

`

我正在开发一个从 sqlite 数据库 android 获取数据的应用程序，我的代码没有错误或警告，但应用程序在启动时崩溃，日志窗口上显示图像上的消息。我搜索了与 sql 相关的错误，但似乎找不到与我还附加的数据库创建代码有关的任何错误。对此的任何帮助都将不胜感激

标签： javaandroid-studioandroid-sqlite