HarmonyOS 鸿蒙Next 使用Preferences存储数据，重新打开元服务后数据没有了

HarmonyOS 鸿蒙Next 使用Preferences存储数据，重新打开元服务后数据没有了

使用Preferences保存数据，TS代码有变动，重启打开元服务后数据没了，请问是什么原因导致的？

const PREFERENCES_NAME = 'theme.db'
const THEME_NAMES: string[] = ['default', 'simplicity', 'pomeloWhtie']
let preferenceTheme: preferences.Preferences | null = null
async testPrefenrence(){
//从内存中获取轻量级存储db文件
await this.getPreferencesFromStorage()
//从轻量级存储db文件中获取键名为theme的键值
this.nowTheme = await this.getPreference()
console.info(`nowTheme__get ${this.nowTheme}`)
}
async getPreferencesFromStorage() {
let context = getContext(this) as Context
preferenceTheme = await preferences.getPreferences(context, PREFERENCES_NAME)
}

async putPreference(data: string) {
Logger.info(TAG, `Put begin`)
if (preferenceTheme !== null) {
await preferenceTheme.put('theme', data)
await preferenceTheme.flush()
}
}

async getPreference(): Promise<string> {
Logger.info(TAG, `Get begin`)
let theme: string = ''
if (preferenceTheme !== null) {
theme = await preferenceTheme.get('theme', 'default') as string
return theme
}
return theme
}