ListView中利用另一方法AdapterView.setOnItemClickListener来设置列表项的点击事件监听器

对比之间在自定义适配器中设置列表项点击事件监听器的方法, 这里说明第二种方法, 这种办法相对更好,更省内存资源

同是Miwok项目, 举个例子, 在NumbersActivity中可以用一种方法设置列表项的点击事件监听器, 之间在NumbersActivity中利用listView.setOnItemClickListener()设置;

另外注意: 在播放完后, 一旦该MediaPlayer对象再被使用,应该调用release()方法将这些资源释放.

public class NumbersActivity extends AppCompatActivity { 
    MediaPlayer mediaPlayer;
    //This listener gets triggered when the {@link MediaPlayer} has completed
    //playing the audio files.
    private MediaPlayer.OnCompletionListener completionListener = new MediaPlayer.OnCompletionListener(){ 
        public void onCompletion(MediaPlayer mediaPlayer){ 
            //Toast.makeText(NumbersActivity.this, "I'm done" , Toast.LENGTH_SHORT).show();
            //Now that the sound file has finished playing, release the media player resources.
            releaseMediaPlayer();
        }
    };
    @Override
    protected void onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_numbers);
        //create a list of Word
        final ArrayList<Word> words = new ArrayList<Word>();
        words.add(new Word("lutti", "one", R.drawable.number_one, R.raw.number_one));
        words.add(new Word("otiiko", "two", R.drawable.number_two,R.raw.number_two));
        words.add(new Word("tolookosu", "three", R.drawable.number_three, R.raw.number_three));
        words.add(new Word("oyyisa", "four", R.drawable.number_four, R.raw.number_four));
        words.add(new Word("massokka", "five", R.drawable.number_five, R.raw.number_five));
        words.add(new Word("temmokka", "six", R.drawable.number_six, R.raw.number_six));
        words.add(new Word("kenekaku", "seven", R.drawable.number_seven, R.raw.number_seven));
        words.add(new Word("kawinta", "eight", R.drawable.number_eight, R.raw.number_eight));
        words.add(new Word("wo'e", "nine", R.drawable.number_nine, R.raw.number_nine));
        words.add(new Word("na'aacha", "ten", R.drawable.number_ten, R.raw.number_ten));
        WordAdapter wordAdapter = new WordAdapter(this, words);
        ListView listView  = (ListView)findViewById(R.id.numbers_list);
        listView.setAdapter(wordAdapter);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener(){ 
            @Override
            //AdapterView: the AdapterView where the Click happened.
            //view: the view within the AdapterView that was clicked(this will be view provided by the adapter).
            //position: the position of the view int the adapter.
            //id: the row id of the item that was clicked.
            public void onItemClick(AdapterView<?> AdapterView, View view, int position, long id) { 
                //Release the media player if it currently exists because we are about to
                //play a different sound file.
                releaseMediaPlayer();
                Word currentWord = words.get(position);
                mediaPlayer = MediaPlayer.create(view.getContext(), currentWord.getAudioResourceId());
                mediaPlayer.start();
                //Setup a listener on the media player, so that we can stop and release the
                //media player once the sounds has finished playing.
                mediaPlayer.setOnCompletionListener(completionListener);
            }
        });
    }
    /** * Clean up the media player by releasing its resources. */
    private void releaseMediaPlayer(){ 
        //If the media player is not null, the it may be currently playing a sound.
        if(mediaPlayer != null){ 
            //Regardless of the current state of the media, release its resources.
            //because wo no longer need it.
            mediaPlayer.release();
            //Set the mediaPlayer back to null.For our code, we've decided that
            //setting the media player to null is an easy way to tell that the media player
            //is not configured to play an audio file at the moment.
            mediaPlayer = null;
        }
    }
}

注意:ListView 和GridView 同是AdapterView的子类
删除第一种设置列表项点击事件监听器的方法, 即在适配器中设置点击事件监听器

public class WordAdapter extends ArrayAdapter<Word> { 
    /** * This is our own custom constructor (it doesn't mirror a superclass constructor). * The context is used to inflate the layout file, and the list is the data we want * to populate into the lists. * * @param context The current context. Used to inflate the layout file. * @param words A List of word objects to display in a list */
    public WordAdapter(Activity context, ArrayList<Word> words){ 
        super(context, 0, words);
    }
    /** * Provides a view for an AdapterView (ListView, GridView, etc.) * * @param position The position in the list of data that should be displayed in the list item view. * @param convertView The recycled view to populate. * @param parent The parent ViewGroup that is used for inflation. * @return The View for the position in the AdapterView. */
    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) { 
        //return super.getView(position, convertView, parent);
        // Check if the existing view is being reuse,otherwise inflate the view
        // (if convertView is null,there is no view to reuse, In this case we will need to inflate
        // one from the list item layout from scratch)
        View listItemView = convertView;
        if(listItemView == null){ 
            //LayoutInflater is an abstract class,and have no static method :inflate(),so
            //we should use LayoutInflater.from(getContext()) method to obtain a LayoutInflater
            //from the given context
            //
            //The third param false, because we don't want to attach the list item view to the parent list view.
            //The'getContext()' parameter is defined in ArrayAdapter.
            listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false);
        }
        //Get the object located at this position in the list. getItem() method from the super class ArrayAdapter
        final Word currentWord =  getItem(position);
        //Find the TextView in the list_item.xml layout with the id.
        //ArrayAdapter don't have the method of 'findViewById()',
        //so must have to use the method of 'View.findViewById()' to find the TextView
        TextView defaultTextView =  (TextView)listItemView.findViewById(R.id.default_text_view);
        defaultTextView.setText(currentWord.getDefaultTranslation());
        //Find the TextView in the list_item.xml layout with the id
        TextView miwokTextView = (TextView)listItemView.findViewById(R.id.miwok_text_view);
        miwokTextView.setText(currentWord.getMiwokTranslation());
        if (currentWord.checkImageResource()) { 
            //Find the ImageView in the list_item.xml layout with the id
            ImageView imageView = (ImageView)listItemView.findViewById(R.id.image_view);
            imageView.setImageResource(currentWord.getImageResourceId());
        }else{ 
            ImageView imageView = (ImageView)listItemView.findViewById(R.id.image_view);
            imageView.setVisibility(View.GONE);
        }
        RelativeLayout textLinearLayout = (RelativeLayout)listItemView.findViewById(R.id.text_relative_layout);
        textLinearLayout.setBackgroundResource(R.color.category_numbers);
// textLinearLayout.setOnClickListener(new View.OnClickListener(){ 
// public void onClick(final View view){ 
// MediaPlayer mediaPlayer = MediaPlayer.create(getContext(), currentWord.getAudioResourceId());
// Toast.makeText(view.getContext(), "Play", Toast.LENGTH_SHORT).show();
// mediaPlayer.start();
// mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener(){ 
//
// public void onCompletion(MediaPlayer mediaPlayer){ 
// //Toast.makeText(view.getContext(),"I'm done!", Toast.LENGTH_SHORT).show();
// mediaPlayer.release();
// }
// });
// }
// });
        return listItemView;
    }
}