android - 当我更正 SQL 表名称中的拼写错误时，为什么我的应用程序会崩溃？

Question

 private static final String TABLE_USERS = "Registerd_Accounts";

当我把它改成这个时私有(private)静态最终字符串TABLE_USERS =“Registered_Accounts”;

当我按下按钮或任何使用数据库的东西时，它崩溃了。当我将其改回拼写错误时，它就可以工作。但是“Registerd_Accounts”仅在处理程序中使用，所以怎么了？在此输入代码。

 package com.set.ultimax.login;

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHandler extends SQLiteOpenHelper {

// All Static variables
// Database Version
private static final int DATABASE_VERSION = 1;

// Database Name
private static final String DATABASE_NAME = "All_Accounts";

private static final String TABLE_USERS = "Registered_Accounts";

// Contacts Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_USERS = "userName";
private static final String KEY_PASS = "passWord";

public DatabaseHandler(Context context) {
    super(context, DATABASE_NAME, null, DATABASE_VERSION);
}

// Creating Tables
@Override
public void onCreate(SQLiteDatabase db) {
    String CREATE_ACCOUNT_TABLE = "CREATE TABLE " + TABLE_USERS + "("
            + KEY_ID + " INTEGER PRIMARY KEY," + KEY_USERS + " TEXT,"
            + KEY_PASS + " TEXT" + ")";
    db.execSQL(CREATE_ACCOUNT_TABLE);
}

// Upgrading database
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // Drop older table if existed
    db.execSQL("DROP TABLE IF EXISTS " + TABLE_USERS);
    onCreate(db);// Create tables again
}

// Adding new User
void addUsers(Users users) {
    SQLiteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_USERS, users.getUser()); // User Name
    values.put(KEY_PASS, users.getPassword()); // Password

    // Inserting Row
    db.insert(TABLE_USERS, null, values);
    db.close(); // Closing database connection
}
public void deleteAll() //Deletes all data in the database
{
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_USERS,null,null);
}

public boolean validateUser(String username, String password){
    Cursor c = getReadableDatabase().rawQuery(
            "SELECT * FROM " + TABLE_USERS + " WHERE "
                    + KEY_USERS + "='" + username +"'AND "+KEY_PASS+"='"+password+"'" ,  null);
    if (c.getCount() > 0) {
        return true;
    }
    else{return false;}

}
public boolean sameUser(String username){
    Cursor c = getReadableDatabase().rawQuery(
            "SELECT * FROM " + TABLE_USERS + " WHERE "
                    + KEY_USERS + "='" + username  + "'" ,  null);
    if (c.getCount() > 0) {
        return true;
    }
    else{return false;}
}

}

这是我的访问器方法

 package com.set.ultimax.login;

  public class Users {

//private variables
int _id; // Just to have it.
String _userName;
String _passWord;

// Empty constructor
public Users(){

}
// constructor
public Users(String userName, String _passWord){
    this._userName = userName;
    this._passWord = _passWord;
}
// getting User
public String getUser(){
    return this._userName;
}

// getting Password
public String getPassword(){
    return this._passWord;
}
}

Answer 1

您应该从设备中卸载该应用程序，然后再次安装并检查它。这可能对您有帮助，因为当我们安装应用程序时，我们的应用程序也会创建本地数据库和数据库表。因此，当您安装时，您的本地数据库已使用拼写错误的表名创建，并且您的应用程序尝试找到正确的拼写表。