How do I call a specific PreferenceFragment from a PreferenceActivity?

Question

I have a PreferenceActivity with several fragments:

R.xml.preferences: (shortened for better readability):

<?xml version="1.0" encoding="utf-8"?>
<preference-headers xmlns:android="http://schemas.android.com/apk/res/android">
    <header android:fragment="fragments.Fragment1" android:id="@+id/fragment1" [...] />
    <header android:fragment="fragments.Fragment2" android:id="@+id/fragment2" [...] />
    [...]
</preference-headers>

SettingsActivity :

public class SettingsActivity extends PreferenceActivity {
    @Override
    public void onBuildHeaders(List<Header> target) {
        loadHeadersFromResource(R.xml.preferences, target);
    }
}

This will show a list entry with fragments.Fragment1 , fragments.Fragment2 , ... if SettingsActivity is started.

But now I want to pass a Bundle such that a specific PreferenceFragment is opened when starting the activity:

so I added this to SettingsActivity :

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    if (savedInstanceState != null && savedInstanceState.getBoolean("shortcut")) {
        // directly jump to fragments.Fragment1
    }
}

I tried to load the fragment via getFragmentManager().findFragmentById(R.id.fragment1) , but this returns null . But even if I had the correct instance, I would not know how to invoke it. Also, calling loadHeadersFromResource(R.xml.preferences_fragment1, target); does not work - This will throw a RuntimeException " XML document must start with tag; foundPreferenceScreen at Binary XML file ". I have no ideas left and also a search on SO and Google did not return any relevant results.

So my question is: Is it possible to directly load a PreferenceFragment (eg fragments.Fragment1) from the Activitiy's onCreate method? If so, how?

Answer 1

According to: http://developer.android.com/reference/android/preference/PreferenceActivity.html#EXTRA_SHOW_FRAGMENT

public static final String EXTRA_SHOW_FRAGMENT

Added in API level 11 When starting this activity, the invoking Intent can contain this extra string to specify which fragment should be initially displayed.

Constant Value: ":android:show_fragment"

intent = new Intent( this, SettingsActivity.class );
intent.putExtra( PreferenceActivity.EXTRA_SHOW_FRAGMENT, Fragment1.class.getName() );
intent.putExtra( PreferenceActivity.EXTRA_NO_HEADERS, true );

Answer 2

只需在onCreate中的PreferenceActivity和PreferenceFragment中使用以下代码即可

addPreferencesFromResource(R.xml.**YOUR PREFERENCE FRAGMENT XML**);

Answer 3

Or use PreferenceActivity.switchToHeader . When starting the PreferenceActivity, the header/overview of all settings pages is loaded first and then the fragment. When finishing the fragment, you will return to the overview.

MyPreferenceActivity:

@Override
public void onBuildHeaders(List<Header> headers) {

    loadHeadersFromResource(R.xml.preference_headers, headers);

    int headerId = getIntent() != null ? getIntent().getIntExtra("header", 0) : 0;
    if (headerId > 0) {
        getIntent().removeExtra("header");
        switchToHeader(findHeaderById(headerId));
    }
}

private Header findHeaderById(long id) {

    if (headers != null)
        for (Header header : headers)
            if (header.id == id) return header;

    return null;
}

This shows how to call the PreferenceActivity together with the fragment in your MainActivity :

Intent intent = new Intent(context, MyPreferenceActivity.class);
intent.putExtra("header", R.id.header1);
intent.putExtra("key", "pref1");
startActivity(intent);

If necessary, you can open the respective preference right away in PreferenceFragment1 :

@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    addPreferencesFromResource(R.xml.preferences_1);  

    String key = getActivity().getIntent() != null ? getActivity().getIntent().getStringExtra("key") : null;

    if (key != null) {
         getActivity().getIntent().removeExtra(key);
         openPreference(key);
    }
}

private void openPreference(String key) {

    PreferenceScreen preferenceScreen = getPreferenceScreen();
    ListAdapter listAdapter = preferenceScreen.getRootAdapter();

    for (int position = 0; position < listAdapter.getCount(); position++) {

        Preference preference = (Preference) listAdapter.getItem(position);

        if (preference.equals(findPreference(key))) {
            preferenceScreen.onItemClick(null, null, position, 0);
            break;
        }
    }
}

preference_headers.xml:

<?xml version="1.0" encoding="utf-8"?>

<preference-headers
    xmlns:android="http://schemas.android.com/apk/res/android">

    <header android:id="@+id/headers1"
        android:fragment="de.almisoft.PreferenceFragment1"
        android:title="Title1"
        android:summary="Summary1">
    </header>

    <header android:id="@+id/headers2"
        android:fragment="de.almisoft.PreferenceFragment2"
        android:title="Title2"
        android:summary="Summary2">
    </header>

</preference-headers>

preferences_1.xml:

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

    <Preference
        android:key="pref1"
        android:title="title"/>

</PreferenceScreen>