sharedPreferences.getString() 返回 null [英] sharedPreferences.getString() return null

问题描述

我正在尝试使用 SharedPreferences 在 textView 中显示用户电子邮件.

Im trying to display the user email in a textView using SharedPreferences.

在 loginActivity 中创建共享首选项.我尝试从 mainActivity 访问它.

Shared preferences is created in loginActivity. I try to access it from mainActivity.

我使用 sharedPreference 的会话运行良好(登录布尔值保存在 sharedPreferences 文件中).

My session using sharedPreference work well (with a login boolean saved in sharedPreferences files).

怎么了?- 上下文错误?- 因为我尝试从另一个活动访问数据?

So what's wrong? - A context error? - Because I try to access the data from an another activity?

请帮忙:) 非常感谢！

Please help :) Thanks a lot!

这是我使用的代码:

• 登录活动:

• Login Activity :

@Override
   protected void onResume() {
     super.onResume();
//In onresume fetching value from sharedpreference
SharedPreferences sharedPreferences =   getSharedPreferences(Config.SHARED_PREF_NAME,Context.MODE_PRIVATE);

//Fetching the boolean value form sharedpreferences
loggedIn = sharedPreferences.getBoolean(Config.LOGGEDIN_SHARED_PREF,   false);

//If we will get true
if(loggedIn){
    //We will start the Profile Activity
    Intent intent = new Intent(LoginActivity.this, MainActivity.class);
    startActivity(intent);
 }
}

...

//Creating a shared preference in a login()
SharedPreferences sharedPreferences = getSharedPreferences(Config.SHARED_PREF_NAME, Context.MODE_PRIVATE);

//Creating editor to store values to shared preferences
SharedPreferences.Editor editor = sharedPreferences.edit();

//Adding values to editor
editor.putBoolean(Config.LOGGEDIN_SHARED_PREF, true);
editor.putString(Config.EMAIL_SHARED_PREF, email);

//Saving values to editor
editor.commit();
...

主要活动:

Main Activity :

@Override
protected void onResume() {
super.onResume();
//In onresume fetching value from sharedpreference
SharedPreferences sharedPreferences = getSharedPreferences(Config.SHARED_PREF_NAME,Context.MODE_PRIVATE);

//Fetching the boolean value form sharedpreferences
email_session = sharedPreferences.getString(Config.EMAIL_SHARED_PREF, "Private");
usernameText.setText(email_session);


}

推荐答案

读取存储的首选项你需要做的:

to read the stored preferences you need to do:

SharedPreferences spref = getSharedPreferences("your_prefs_name", Activity.MODE_PRIVATE);
SharedPreferences.Editor editor = spref.edit();
editor.putString("myTextViewValue", prefVal); //
editor.commit();

阅读

SharedPreferences preferences = getPreferences(Activity.MODE_PRIVATE);
String storedPreference = preferences.getStr("myTextViewValue", null);

这篇关于sharedPreferences.getString() 返回 null的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！