Java tutorial
/* * Copyright (C) 2012 - 2013 Niall 'Rivernile' Scott * * This software is provided 'as-is', without any express or implied * warranty. In no event will the authors or contributors be held liable for * any damages arising from the use of this software. * * The aforementioned copyright holder(s) hereby grant you a * non-transferrable right to use this software for any purpose (including * commercial applications), and to modify it and redistribute it, subject to * the following conditions: * * 1. This notice may not be removed or altered from any file it appears in. * * 2. Any modifications made to this software, except those defined in * clause 3 of this agreement, must be released under this license, and * the source code of any modifications must be made available on a * publically accessible (and locateable) website, or sent to the * original author of this software. * * 3. Software modifications that do not alter the functionality of the * software but are simply adaptations to a specific environment are * exempt from clause 2. */ package uk.org.rivernile.edinburghbustracker.android.fragments.dialogs; import android.app.Activity; import android.app.AlertDialog; import android.app.Dialog; import android.content.DialogInterface; import android.os.Bundle; import android.support.v4.app.DialogFragment; import uk.org.rivernile.edinburghbustracker.android.R; /** * This DialogFragment allows the user to select bus services from a list and * store the user's selection. This may be used to ask the user to filter bus * services or to say which services they are interested in. * * @author Niall Scott */ public class ServicesChooserDialogFragment extends DialogFragment { /** The argument name for services. */ private static final String ARG_SERVICES = "services"; /** The argument name for the default selected services. */ private static final String ARG_SELECTED_SERVICES = "selectedServices"; /** The argument name for the dialog title. */ private static final String ARG_TITLE = "dialogTitle"; /** The argument name for check boxes, stored in the instance state. */ private static final String ARG_CHECK_BOXES = "checkBoxes"; private Callbacks callbacks; private String[] services; private boolean[] checkBoxes; /** * Create a new instance of this Fragment, providing a list of services to * select from, a list of services to select by default and a title for the * Dialog. * * @param services The list of services to show to the user. * @param selectedServices The services to select by default, null if none. * @param dialogTitle The title to use for the Dialog. * @return A new instance of this Fragment. */ public static ServicesChooserDialogFragment newInstance(final String[] services, final String[] selectedServices, final String dialogTitle) { final ServicesChooserDialogFragment f = new ServicesChooserDialogFragment(); final Bundle b = new Bundle(); b.putStringArray(ARG_SERVICES, services); b.putStringArray(ARG_SELECTED_SERVICES, selectedServices); b.putString(ARG_TITLE, dialogTitle); f.setArguments(b); return f; } /** * {@inheritDoc} */ @Override public void onAttach(final Activity activity) { super.onAttach(activity); try { callbacks = (Callbacks) activity; } catch (ClassCastException e) { throw new IllegalStateException( activity.getClass().getName() + " does not implement " + Callbacks.class.getName()); } } /** * {@inheritDoc} */ @Override public void onCreate(final Bundle savedInstanceState) { super.onCreate(savedInstanceState); final Bundle args = getArguments(); services = args.getStringArray(ARG_SERVICES); // Do sanity checks. if (services == null || services.length == 0) { throw new IllegalArgumentException("A list of services must " + "be supplied."); } if (savedInstanceState != null) { // If there is a previous instance, get the args from the saved // instance state. checkBoxes = savedInstanceState.getBooleanArray(ARG_CHECK_BOXES); } else { final String[] selectedServices = args.getStringArray(ARG_SELECTED_SERVICES); checkBoxes = new boolean[services.length]; if (selectedServices != null && selectedServices.length > 0) { int i; final int len = services.length; for (i = 0; i < len; i++) { for (String s : selectedServices) { if (services[i].equals(s)) { checkBoxes[i] = true; break; } } } } } } /** * {@inheritDoc} */ @Override public void onSaveInstanceState(final Bundle outState) { super.onSaveInstanceState(outState); // Save the state. outState.putBooleanArray(ARG_CHECK_BOXES, checkBoxes); } /** * {@inheritDoc} */ @Override public Dialog onCreateDialog(final Bundle savedInstanceState) { // Build the Dialog. final AlertDialog.Builder builder = new AlertDialog.Builder(getActivity()); builder.setTitle(getArguments().getString(ARG_TITLE)); builder.setMultiChoiceItems(services, checkBoxes, new DialogInterface.OnMultiChoiceClickListener() { @Override public void onClick(final DialogInterface dialog, final int which, boolean isChecked) { // Change the flag for that service. checkBoxes[which] = isChecked; } }); builder.setPositiveButton(R.string.close, null); return builder.create(); } /** * {@inheritDoc} */ @Override public void onDismiss(final DialogInterface dialog) { super.onDismiss(dialog); // Tell the listener that there may be changes. callbacks.onServicesChosen(getChosenServices()); } /** * Get the list of services that was supplied to the constructor. * * @return A list of bus services to choose from. */ public String[] getServices() { return services; } /** * Get a String array of the chosen services. * * @return A String array of the chosen services. */ public String[] getChosenServices() { int counter = 0; // Firstly, count the number of chosen services so we know how big to // make the String array. for (boolean b : checkBoxes) { if (b) counter++; } // If there's no chosen services, return an empty array. if (counter == 0) return new String[] {}; // Create the array of the determined size. final String[] items = new String[counter]; int i = 0; final int len = checkBoxes.length; // Loop through the check boxes, if it is selected, add it to the output // String array. for (int j = 0; j < len; j++) { if (checkBoxes[j]) { items[i] = services[j]; i++; } } return items; } /** * Get a String representation of the chosen services. * * @return A String representation of the chosen services. */ public String getChosenServicesAsString() { return getChosenServicesAsString(getChosenServices()); } /** * Get a String representation of the chosen services. * * @param chosenServices A String array of chosen services. * @return A String representation of the chosen services. */ public static String getChosenServicesAsString(final String[] chosenServices) { // If there are no chosen services, return an empty String. if (chosenServices == null || chosenServices.length == 0) { return ""; } final StringBuilder sb = new StringBuilder(); boolean isFirst = true; for (String s : chosenServices) { if (isFirst) { // Used to format the String correctly. sb.append(s); isFirst = false; } else { sb.append(',').append(' ').append(s); } } return sb.toString(); } /** * Any Activities which host this Fragment must implement this interface to * handle navigation events. */ public static interface Callbacks { /** * This is called when the user dismisses the service chooser dialog. * This will get called even when no services are chosen, and may not * necessarily mean that the user has made a new selection. * * @param chosenServices A String array of chosen services. */ public void onServicesChosen(String[] chosenServices); } }