Android共享偏好强制关闭

Question

I am trying to use sharedpreferences in a PreferenceActivity, but unfortunately it force closes. Part of it:

public class EditPreferences extends PreferenceActivity {

String ListPreference;
boolean CheckboxPreference;
SharedPreferences mprefs;
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences);


final CheckBoxPreference checkboxPref = (CheckBoxPreference) getPreferenceManager().findPreference("checkboxPref");

checkboxPref.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {            
public boolean onPreferenceChange(Preference preference, Object newValue) {
    if (newValue.toString().equals("true"))
    {  
        Toast.makeText(getApplicationContext(), "CB: " + "true", Toast.LENGTH_SHORT).show();
        SharedPreferences.Editor edit = mprefs.edit();
        edit.putString("cbstate", "true");
        edit.commit();
    } 
    else 
    {  
        Toast.makeText(getApplicationContext(), "CB: " + "false", Toast.LENGTH_SHORT).show();
    SharedPreferences.Editor edit = mprefs.edit(); //this line force closes
        edit.putString("cbstate", "false");
        edit.commit();
    }
    return true;
}

});

What is wrong with the code? Thanks, B

Answer 1

它看起来不像mprefs被分配了一个值（除非它发生在其他地方）

Answer 2

You should look at the log to see the stack crawl of the exception, which tells you why your code is crashing.

I am not adding this as a question for clarification, because the fact that a stack crawl is not included in the question is a strong indication that you haven't actually looked at it, and if that is the case then the answer to your question and most likely solution to your problem is to go look at that and see why it says you are crashing.