SettingsActivity.java

package com.frozendevs.periodictable.activity;

import android.content.res.Configuration;
import android.os.Bundle;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.support.annotation.LayoutRes;
import android.support.annotation.Nullable;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatDelegate;
import android.support.v7.widget.Toolbar;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebView;

import com.frozendevs.periodictable.R;

public class SettingsActivity extends PreferenceActivity {
    private final static String ACTION_SETTINGS_ABOUT = "com.frozendevs.periodictable.SETTINGS_ABOUT";

    private AppCompatDelegate mDelegate;

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

        super.onCreate(savedInstanceState);

        String action = getIntent().getAction();

        if (action != null && action.equals(ACTION_SETTINGS_ABOUT)) {
            addPreferencesFromResource(R.xml.settings_about);

            String versionName;
            try {
                versionName = getPackageManager().getPackageInfo(getPackageName(), 0).versionName;
            } catch (Exception e) {
                versionName = getString(R.string.preference_version_number_unknown);
            }
            findPreference("version").setSummary(versionName);

            findPreference("licences").setOnPreferenceClickListener(
                    new Preference.OnPreferenceClickListener() {
                        @Override
                        public boolean onPreferenceClick(Preference preference) {
                            WebView webView = new WebView(getApplicationContext());
                            webView.loadUrl("file:///android_asset/html/licenses.html");

                            AlertDialog dialog = new AlertDialog.Builder(SettingsActivity.this).
                                    create();
                            dialog.setTitle(R.string.preference_open_source_licences);
                            dialog.setView(webView);
                            dialog.show();

                            return true;
                        }
                    });
        } else {
            addPreferencesFromResource(R.xml.settings);
        }
    }

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

        getDelegate().onPostCreate(savedInstanceState);
    }

    public ActionBar getSupportActionBar() {
        return getDelegate().getSupportActionBar();
    }

    public void setSupportActionBar(@Nullable Toolbar toolbar) {
        getDelegate().setSupportActionBar(toolbar);
    }

    @Override
    public MenuInflater getMenuInflater() {
        return getDelegate().getMenuInflater();
    }

    @Override
    public void setContentView(@LayoutRes int layoutResID) {
        getDelegate().setContentView(layoutResID);
    }

    @Override
    public void setContentView(View view) {
        getDelegate().setContentView(view);
    }

    @Override
    public void setContentView(View view, ViewGroup.LayoutParams params) {
        getDelegate().setContentView(view, params);
    }

    @Override
    public void addContentView(View view, ViewGroup.LayoutParams params) {
        getDelegate().addContentView(view, params);
    }

    @Override
    protected void onPostResume() {
        super.onPostResume();

        getDelegate().onPostResume();
    }

    @Override
    protected void onTitleChanged(CharSequence title, int color) {
        super.onTitleChanged(title, color);

        getDelegate().setTitle(title);
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);

        getDelegate().onConfigurationChanged(newConfig);
    }

    @Override
    protected void onStop() {
        super.onStop();

        getDelegate().onStop();
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();

        getDelegate().onDestroy();
    }

    public void invalidateOptionsMenu() {
        getDelegate().invalidateOptionsMenu();
    }

    private AppCompatDelegate getDelegate() {
        if (mDelegate == null) {
            mDelegate = AppCompatDelegate.create(this, null);
        }

        return mDelegate;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
            case android.R.id.home:
                finish();
                return true;
        }

        return super.onOptionsItemSelected(item);
    }
}