Кюветы Android, Часть 1: SDK

/*
 * Copyright 2012 David Cesarino de Sousa
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.davidcesarino.android.common.ui;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.DatePickerDialog;
import android.app.DatePickerDialog.OnDateSetListener;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.DialogFragment;
import android.widget.DatePicker;

/**
 * <p>Provides a usable {@link DatePickerDialog} wrapped as a {@link DialogFragment},
 * using the compatibility package v4. Its main advantage is handling Issue 34833 
 * automatically for you.</p>
 * 
 * <p>Current implementation (because I wanted that way =) ):</p>
 * 
 * <ul>
 * <li>Only two buttons, a {@code BUTTON_POSITIVE} and a {@code BUTTON_NEGATIVE}.
 * <li>Buttons labeled from {@code android.R.string.ok} and {@code android.R.string.cancel}.
 * </ul>
 * 
 * <p><strong>Usage sample:</strong></p>
 * 
 * <pre>class YourActivity extends Activity implements OnDateSetListener
 * 
 * // ...
 * 
 * Bundle b = new Bundle();
 * b.putInt(DatePickerDialogFragment.YEAR, 2012);
 * b.putInt(DatePickerDialogFragment.MONTH, 6);
 * b.putInt(DatePickerDialogFragment.DATE, 17);
 * DialogFragment picker = new DatePickerDialogFragment();
 * picker.setArguments(b);
 * picker.show(getActivity().getSupportFragmentManager(), "fragment_date_picker");</pre>
 * 
 * @author davidcesarino@gmail.com
 * @version 2015.0904
 * @see <a href="http://code.google.com/p/android/issues/detail?id=34833">Android Issue 34833</a>
 * @see <a href="http://stackoverflow.com/q/11444238/489607"
 * >Jelly Bean DatePickerDialog — is there a way to cancel?</a>
 *
 */
public class DatePickerDialogFragment extends DialogFragment {
    
    public static final String YEAR = "Year";
    public static final String MONTH = "Month";
    public static final String DATE = "Day";
    
    private OnDateSetListener mListener;
    
    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        this.mListener = (OnDateSetListener) activity;
    }
    
    @Override
    public void onDetach() {
        this.mListener = null;
        super.onDetach();
    }
    
    @TargetApi(11)
    @Override
    public Dialog onCreateDialog(Bundle savedInstanceState) {
        Bundle b = getArguments();
        int y = b.getInt(YEAR);
        int m = b.getInt(MONTH);
        int d = b.getInt(DATE);
        
        // Jelly Bean introduced a bug in DatePickerDialog (and possibly 
        // TimePickerDialog as well), and one of the possible solutions is 
        // to postpone the creation of both the listener and the BUTTON_* .
        // 
        // Passing a null here won't harm because DatePickerDialog checks for a null
        // whenever it reads the listener that was passed here. >>> This seems to be 
        // true down to 1.5 / API 3, up to 4.1.1 / API 16. <<< No worries. For now.
        //
        // See my own question and answer, and details I included for the issue:
        //
        // http://stackoverflow.com/a/11493752/489607
        // http://code.google.com/p/android/issues/detail?id=34833
        //
        // Of course, suggestions welcome.
        
        final DatePickerDialog picker = new DatePickerDialog(getActivity(),
                getConstructorListener(), y, m, d);

        if (isAffectedVersion()) {
            picker.setButton(DialogInterface.BUTTON_POSITIVE,
                    getActivity().getString(android.R.string.ok),
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            DatePicker dp = picker.getDatePicker();
                            mListener.onDateSet(dp,
                                    dp.getYear(), dp.getMonth(), dp.getDayOfMonth());
                        }
                    });
            picker.setButton(DialogInterface.BUTTON_NEGATIVE,
                    getActivity().getString(android.R.string.cancel),
                    new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {}
                    });
        }
        return picker;
    }

    private static boolean isAffectedVersion() {
        return Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN
                && Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP;
    }

    private OnDateSetListener getConstructorListener() {
        return isAffectedVersion() ? null : mListener;
    }
}

import android.content.Context;
import android.database.DataSetObserver;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListAdapter;
import android.widget.SpinnerAdapter;

/**
 * Decorator Adapter to allow a Spinner to show a 'Nothing Selected...' initially
 * displayed instead of the first choice in the Adapter.
 */
public class NothingSelectedSpinnerAdapter implements SpinnerAdapter, ListAdapter {

    protected static final int EXTRA = 1;
    protected SpinnerAdapter adapter;
    protected Context context;
    protected int nothingSelectedLayout;
    protected int nothingSelectedDropdownLayout;
    protected LayoutInflater layoutInflater;

    /**
     * Use this constructor to have NO 'Select One...' item, instead use
     * the standard prompt or nothing at all.
     * @param spinnerAdapter wrapped Adapter.
     * @param nothingSelectedLayout layout for nothing selected, perhaps
     * you want text grayed out like a prompt...
     * @param context
     */
    public NothingSelectedSpinnerAdapter(
      SpinnerAdapter spinnerAdapter,
      int nothingSelectedLayout, Context context) {

        this(spinnerAdapter, nothingSelectedLayout, -1, context);
    }

    /**
     * Use this constructor to Define your 'Select One...' layout as the first
     * row in the returned choices.
     * If you do this, you probably don't want a prompt on your spinner or it'll
     * have two 'Select' rows.
     * @param spinnerAdapter wrapped Adapter. Should probably return false for isEnabled(0)
     * @param nothingSelectedLayout layout for nothing selected, perhaps you want
     * text grayed out like a prompt...
     * @param nothingSelectedDropdownLayout layout for your 'Select an Item...' in
     * the dropdown.
     * @param context
     */
    public NothingSelectedSpinnerAdapter(SpinnerAdapter spinnerAdapter,
            int nothingSelectedLayout, int nothingSelectedDropdownLayout, Context context) {
        this.adapter = spinnerAdapter;
        this.context = context;
        this.nothingSelectedLayout = nothingSelectedLayout;
        this.nothingSelectedDropdownLayout = nothingSelectedDropdownLayout;
        layoutInflater = LayoutInflater.from(context);
    }

    @Override
    public final View getView(int position, View convertView, ViewGroup parent) {
        // This provides the View for the Selected Item in the Spinner, not
        // the dropdown (unless dropdownView is not set).
        if (position == 0) {
            return getNothingSelectedView(parent);
        }
        return adapter.getView(position - EXTRA, null, parent); // Could re-use
                                                 // the convertView if possible.
    }

    /**
     * View to show in Spinner with Nothing Selected
     * Override this to do something dynamic... e.g. "37 Options Found"
     * @param parent
     * @return
     */
    protected View getNothingSelectedView(ViewGroup parent) {
        return layoutInflater.inflate(nothingSelectedLayout, parent, false);
    }

    @Override
    public View getDropDownView(int position, View convertView, ViewGroup parent) {
        // Android BUG! http://code.google.com/p/android/issues/detail?id=17128 -
        // Spinner does not support multiple view types
        if (position == 0) {
            return nothingSelectedDropdownLayout == -1 ?
              new View(context) :
              getNothingSelectedDropdownView(parent);
        }

        // Could re-use the convertView if possible, use setTag...
        return adapter.getDropDownView(position - EXTRA, null, parent);
    }

    /**
     * Override this to do something dynamic... For example, "Pick your favorite
     * of these 37".
     * @param parent
     * @return
     */
    protected View getNothingSelectedDropdownView(ViewGroup parent) {
        return layoutInflater.inflate(nothingSelectedDropdownLayout, parent, false);
    }

    @Override
    public int getCount() {
        int count = adapter.getCount();
        return count == 0 ? 0 : count + EXTRA;
    }

    @Override
    public Object getItem(int position) {
        return position == 0 ? null : adapter.getItem(position - EXTRA);
    }

    @Override
    public int getItemViewType(int position) {
        return 0;
    }

    @Override
    public int getViewTypeCount() {
        return 1;
    }

    @Override
    public long getItemId(int position) {
        return position >= EXTRA ? adapter.getItemId(position - EXTRA) : position - EXTRA;
    }

    @Override
    public boolean hasStableIds() {
        return adapter.hasStableIds();
    }

    @Override
    public boolean isEmpty() {
        return adapter.isEmpty();
    }

    @Override
    public void registerDataSetObserver(DataSetObserver observer) {
        adapter.registerDataSetObserver(observer);
    }

    @Override
    public void unregisterDataSetObserver(DataSetObserver observer) {
        adapter.unregisterDataSetObserver(observer);
    }

    @Override
    public boolean areAllItemsEnabled() {
        return false;
    }

    @Override
    public boolean isEnabled(int position) {
        return position != 0; // Don't allow the 'nothing selected'
                                             // item to be picked.
    }

}

Spinner spinner = (Spinner) findViewById(R.id.spinner);
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.planets_array, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spinner.setPrompt("Select your favorite Planet!");

    spinner.setAdapter(
      new NothingSelectedSpinnerAdapter(
            adapter,
            R.layout.contact_spinner_row_nothing_selected,
            // R.layout.contact_spinner_nothing_selected_dropdown, // Optional
            this));