不同 activity 中的 SharedPreferences

Question

我用下面的代码从 activity A 中加载 SharedPreferences：

private void SavePreferences(String key, String value){
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);

    SharedPreferences.Editor editor = sharedPreferences.edit();
    editor.putString(key, value);
    editor.commit();
   }

在 activity B 中我想加载 SharedPreferences。下面是一个异常 NullPointerException:

private void LoadPreferences(){   
       SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
       data = sharedPreferences.getString("name", "08:00") ;
   }

我用下面的代码，得到这个编译错误："No enclosing instance of the type A is accessible in scope"

 private void LoadPreferences(){   
       SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(A.this);
       data = sharedPreferences.getString("name", "08:00") ;
   }

如何访问数据？谢谢！

Answer 1

在两个 Activities 中把 this 替换为 getApplicationContext()
在Activity A 的 SharedPreferences 是下面的方式：

private void SavePreferences(String key, String value){
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());

        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putString(key, value);
        editor.commit();
        Intent sd=new Intent(this,Secongtess.class);
        startActivity(sd);
       }

Activity B 中按下面的方式获取值：

 private void LoadPreferences(){   
       SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
     String  data = sharedPreferences.getString("name", "08:00") ;
     Toast.makeText(this,data, Toast.LENGTH_LONG).show();
   }