SettingsActivity.java

package moe.kurumi.moegallery.activity;

import android.content.pm.PackageManager;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceFragment;
import android.support.annotation.Nullable;

import moe.kurumi.moegallery.R;

public class SettingsActivity extends PreferenceActivity {

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

        if (savedInstanceState == null) {
            getFragmentManager().beginTransaction()
                    .add(android.R.id.content, new SettingsFragment())
                    .commit();
        }
    }

    public static class SettingsFragment extends PreferenceFragment {
        Preference version;

        @Override
        public void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            addPreferencesFromResource(R.xml.settings);
            initPrefs();
        }

        void initPrefs() {
            try {
                PackageManager packageManager = getActivity().getPackageManager();
                String versionString = packageManager.getPackageInfo(getActivity().getPackageName(),
                        0).versionName;
                version = findPreference(getString(R.string.version_key));
                version.setSummary(versionString);
            } catch (PackageManager.NameNotFoundException e) {
                e.printStackTrace();
            }
        }
    }

}