Java – why can’t I add the first header to getpreferencescreen?

The standard setting activity from Google Android studio now displays the first title "general" So I modified the code, but when getpreferencescreen () first appeared, I got Java lang.NullPointerException. addPreference(fakeHeader);

private void setupSimplePreferencesScreen() {
    if (!isSimplePreferences(this)) {
        return;
    }


    PreferenceCategory fakeHeader = new PreferenceCategory(this);
    fakeHeader.setTitle(R.string.pref_header_notifications);
    getPreferenceScreen().addPreference(fakeHeader);
    addPreferencesFromResource(R.xml.pref_general);



      fakeHeader = new PreferenceCategory(this);
    fakeHeader.setTitle(R.string.pref_header_notifications);
    getPreferenceScreen().addPreference(fakeHeader);
    addPreferencesFromResource(R.xml.pref_notification);

    bindPreferenceSummaryToValue(findPreference("username"));
    bindPreferenceSummaryToValue(findPreference("password"));
    bindPreferenceSummaryToValue(findPreference("server"));

}

    @Override
@TargetApi(Build.VERSION_CODES.HONEYCOMB)
public void onBuildHeaders(List<Header> target) {
    if (!isSimplePreferences(this)) {
        loadHeadersFromResource(R.xml.pref_headers,target);
    }
}

<header
    android:fragment="com.example.eslam.rottapharm.SettingsActivity$GeneralPreferenceFragment"
    android:title="@string/pref_header_general" />
</preference-headers>

Solution

Well, I figured it out, because it's annoying for me, too Therefore, in order to display the title of the first preference section (for example, general), I added another XML file (preferencescreen) as a container I call it Pref_ container. XML, which is located in the XML directory along with other preference header files, such as Pref_ general. xml,pref_ notification. XML, etc Code:

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android">
</PreferenceScreen>

Then, in settingsactivity In Java, I have:

// Add container
addPreferencesFromResource(R.xml.pref_container);

// Add 'general' preferences,and a corresponding header.
PreferenceCategory fakeHeader = new PreferenceCategory(this);
fakeHeader.setTitle(R.string.pref_header_general);
getPreferenceScreen().addPreference(fakeHeader);
addPreferencesFromResource(R.xml.pref_general);

// Add 'backup' preferences,and a corresponding header.
fakeHeader = new PreferenceCategory(this);
fakeHeader.setTitle(R.string.pref_header_backup);
getPreferenceScreen().addPreference(fakeHeader);
addPreferencesFromResource(R.xml.pref_backup);

This is very useful to me