PreferenceFragment frag = new PreferenceFragment() gives a warning

Question

I have the below code and the line PreferenceFragment frag = new PreferenceFragment() returns a warning, which I don't know how to resolve:

import android.content.Intent;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceFragment;
import android.util.Log;
import android.widget.Toast;

import com.time.myapplication.NotificationCenter;
import com.time.myapplication.R;
import com.time.myapplication.data.DeadlinesUtils;

public class Settings extends PreferenceActivity {
private static final int RESULT_RECOVER_PICK = 1;
private static final String TAG = "Settings";

@Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);

   PreferenceFragment frag = new PreferenceFragment(){
       @Override
       public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       addPreferencesFromResource(R.xml.preferences);

      Preference prefPersis = findPreference(getString(R.string.pref_key_notif_persist));
   prefPersist.setOnPreferenceChangeListener(new Preference.OnPreferenceChangeListener() {
                public boolean onPreferenceChange(Preference preference, Object newValue) {
                    String act = (Boolean) newValue
                            ? NotificationCenter.ACTION_SHOW
                            : NotificationCenter.ACTION_HIDE;
                    sendBroadcast(new Intent(act));
                    return true;
                }
            });

            Preference prefToggle = findPreference(getString(R.string.pref_key_notif_toggle));
            prefToggle.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
                public boolean onPreferenceClick(Preference preference) {
                    sendBroadcast(new Intent(NotificationCenter.ACTION_TOGGLE));
                    return true;
                }
            });

            Preference prefBackup = findPreference(getString(R.string.pref_key_backup_do));
            prefBackup.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
                public boolean onPreferenceClick(Preference preference) {
                    Intent i = new Intent();
                    i.setAction(Intent.ACTION_SEND);
                    i.setType("text/plain");
                    i.putExtra(Intent.EXTRA_STREAM, DeadlinesUtils.performBackup(getApplicationContext()));
                    startActivity(i);
                    return true;
                }
            });

            Preference prefRecover = findPreference(getString(R.string.pref_key_recover_do));
            prefRecover.setOnPreferenceClickListener(new Preference.OnPreferenceClickListener() {
                @Override
                public boolean onPreferenceClick(Preference preference) {
                    Intent i = new Intent(Intent.ACTION_GET_CONTENT);
                    i.setType("*/*");
                    Settings.this.startActivityForResult(i, RESULT_RECOVER_PICK);
                    return true;
                }
            });

            Preference prefVersion = findPreference(getString(R.string.pref_key_about_version));
            try {
                PackageInfo pkgInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
                prefVersion.setSummary(pkgInfo.versionName);
            } catch (PackageManager.NameNotFoundException ex) {
                Log.e(TAG, "Failed to retrieve version number", ex); // FIXME translate
            }
        }
    };

    getFragmentManager().beginTransaction()
            .replace(android.R.id.content, frag)
            .commit();
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (RESULT_RECOVER_PICK == requestCode) {
        if (RESULT_OK == resultCode)
            DeadlinesUtils.performRecover(getApplicationContext(), data.getData());
        else
            Toast.makeText(this, "Failed to perform recover", Toast.LENGTH_SHORT).show(); // FIXME translate
    }
}
}

The warning message is

Fragments should be static such that they can be re-instantiated by the system, and anonymous classes are not static less... (Ctrl+F1)

Inspection info:From the Fragment documentation: Every fragment must have an empty constructor, so it can be instantiated when restoring its activity's state. It is strongly recommended that subclasses do not have other constructors with parameters, since these constructors will not be called when the fragment is re-instantiated; instead, arguments can be supplied by the caller with setArguments(Bundle) and later retrieved by the Fragment with getArguments().

Note that this is no longer true when you are using androidx.fragment.app.Fragment; with the FragmentFactory you can supply any arguments you want (as of version androidx version 1.1). Issue id: ValidFragment

What am I doing wrong?

The warning message seems pretty self-explantory and detailed. What don't you understand? — Aiyuni, Jul 30 '19 at 18:10
@Aiyuni I dont understand the warning and I try many different solution but still getting this error. — Jay Leee, Jul 30 '19 at 18:19
Please edit your question to include your attempted solutions — Aiyuni, Jul 30 '19 at 18:26

Ramees Thattarath · Answer 1 · 2019-07-30T19:18:44.733

Fragment is designed in such a way that fragment transactions will be remembered by the system across activity instances (such as when orientation change happens...), that is the last fragment transaction is recommitted by the system after creating a fragment instance internally.

In short it should be possible for the system to instantiate your fragment object.

The current PreferenceFragment that you have created does not support this use case as you have created the PreferenceFragment as an anonymous object inside onCreate method .

Refer this link on same issue

Solution is to create an independent class or static inner class extending PreferenceFragment and override required hook methods. If you want to pass any data from activity to fragment use arguments for the same

PreferenceFragment frag = new PreferenceFragment() gives a warning

1 Answers1