SettingsActivity.java

package com.pedrocarrillo.expensetracker.ui.settings;

import android.content.SharedPreferences;
import android.os.Bundle;
import android.preference.ListPreference;
import android.preference.Preference;
import android.preference.PreferenceActivity;
import android.preference.PreferenceManager;
import android.support.annotation.LayoutRes;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatDelegate;
import android.support.v7.widget.Toolbar;
import android.view.View;

import com.pedrocarrillo.expensetracker.R;

/**
 * Created by pcarrillo on 22/09/2015.
 */
public class SettingsActivity  extends PreferenceActivity
        implements Preference.OnPreferenceChangeListener, SharedPreferences.OnSharedPreferenceChangeListener {

    private AppCompatDelegate mDelegate;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        // Add 'general' preferences, defined in the XML file
        getDelegate().installViewFactory();
        getDelegate().onCreate(savedInstanceState);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.settings_activity);
        setToolbar((Toolbar) findViewById(R.id.toolbar));
        addPreferencesFromResource(R.xml.pref_general);

        // For all preferences, attach an OnPreferenceChangeListener so the UI summary can be
        // updated when the preference changes.
        bindPreferenceSummaryToValue(findPreference(getString(R.string.pref_country_key)));
        bindPreferenceSummaryToValue(findPreference(getString(R.string.date_format_key)));
    }

    private void setToolbar(Toolbar mToolbar) {
        setSupportActionBar(mToolbar);
        getDelegate().getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        mToolbar.setNavigationIcon(getResources().getDrawable(R.drawable.abc_ic_ab_back_mtrl_am_alpha));
        mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                onBackPressed();
            }
        });
    }

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

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

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

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

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

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

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


    // Registers a shared preference change listener that gets notified when preferences change
    @Override
    protected void onResume() {
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
        sp.registerOnSharedPreferenceChangeListener(this);
        super.onResume();
    }

    // Unregisters a shared preference change listener
    @Override
    protected void onPause() {
        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(this);
        sp.unregisterOnSharedPreferenceChangeListener(this);
        super.onPause();
    }

    // This gets called before the preference is changed
    @Override
    public boolean onPreferenceChange(Preference preference, Object value) {
        setPreferenceSummary(preference, value);
        return true;
    }

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {

    }

    private void bindPreferenceSummaryToValue(Preference preference) {

        preference.setOnPreferenceChangeListener(this);
        setPreferenceSummary(preference,
                PreferenceManager
                        .getDefaultSharedPreferences(preference.getContext())
                        .getString(preference.getKey(), ""));
    }

    private void setPreferenceSummary(Preference preference, Object value) {
        String stringValue = value.toString();
        String key = preference.getKey();

        if (preference instanceof ListPreference) {
            // For list preferences, look up the correct display value in
            // the preference's 'entries' list (since they have separate labels/values).
            ListPreference listPreference = (ListPreference) preference;
            int prefIndex = listPreference.findIndexOfValue(stringValue);
            if (prefIndex >= 0) {
                preference.setSummary(listPreference.getEntries()[prefIndex]);
            }
        }

    }
}