SharedPerferences似乎不起作用

Question

I'm trying to use SharedPreferences in my app but it just doesn't seem to be working.

First, I declare SharedPreferences as a global variable in the activity where I'm planning to use them:

SharedPreferences prefs;

Then I set the default SharedPreferences in onCreate:

prefs = getSharedPreferences("urnikSp", 0);
SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("schudeleDownloaded", false);
editor.commit();

I then change the boolean value when a certain action is completed:

prefs.edit().putBoolean("schudeleDownloaded", true).commit();

And then in the same activity (when it is restarted), I check for the boolean value in onCreate like this:

boolean schudeleDownloaded = prefs.getBoolean("schudeleDownloaded", false);
if (!schudeleDownloaded){
    new PopulateDatabase().execute();
}

And even though I clearly set the new value to "true" upon completing a certain action, the IF statement you see above still executes because the boolean value still seems to be false.

What am I doing wrong?

Answer 1

Let me do a wild guess. Because when you restart, you set it to false again.... It is in onCreate function.

Answer 2

如果您正在重新创建活动，则将再次调用onCreate（）方法，因此我认为您将其值改回false

Answer 3

You have to create a separate SharedPreferences.Editor instance. So instead of doing this:

prefs.edit().putBoolean("schudeleDownloaded", true).commit();

Try this:

SharedPreferences.Editor editor = prefs.edit();
editor.putBoolean("schedeleDownloaded", true);
editor.commit();