ListView中notifyDataSetChanged()刷新数据不更新原因分析

标题 : 不作死就不会死!!!!!!

类 : ActivityA,ActivityB,BookListAdapter,Book,HttpManager

测试顺序 : ActivityA >> ActivityB >> ActivityA(ActivityB"销毁") >> ActivityB

嘿嘿!!!! 出现如下:

Bug :

每次点击按钮都是从异步获取数据显示到listview中，运行时第一次点击没问题，数据获取并都显示正常，但是这个listview所在的ActivityB关闭掉后，重新点击按钮时，listview竟然没任何数据了 ...WTF...

解决方法:

1.(渣渣方案)把HttpManager 中 asyncBooks方法中的

       if (mListener == null) {
            mListener = listener;
        }

改为

      mListener = listener;

2.把 HttpManager 中的方法改为非static的,在ActivityB中直接new HttpManager()一个对象:

public class ActivityB extends AppCompatActivity implements HttpManager.LoadBookListener {
    ......
    HttpManager httpManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        ......
        httpManager = new HttpManager();
    }
    @Override
    protected void onResume() {
        ......
        httpManager.asyncBooks(this);
    }
    ......
}

总结: 如非必要,不要使用static做方法及参数的修饰符!!!!! 会引起一些不为人知的内存泄漏

ActivityA

public class ActivityA extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_A);
    }
    public void onClick(View view) {
        startActivity(new Intent(this, ActivityB.class));
    }
}

ActivityB

public class ActivityB extends AppCompatActivity implements HttpManager.LoadBookListener {
    private BookListAdapter adapter;
    private ListView list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_B);
        initView();
    }
    private void initView() {
        listView = (ListView) findViewById(R.id.listView);
        adapter = new BookListAdapter();
        listView.setAdapter(adapter);
    }
    @Override
    protected void onResume() {
        super.onResume();
        HttpManager.asyncBooks(this);
    }
    @Override
    public void onLoadBooksEnd(final List books) {
        adapter.addAll(books, true);
    }
}

BookListAdapter

class BookListAdapter extends MyBaseAdapter {
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        ViewHolder viewHolder;
        if (view == null) {
            view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.inflate_book_list, viewGroup, false);
            viewHolder = new ViewHolder(view);
            view.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) view.getTag();
        }Book book = getItem(i);
        viewHolder.imgBook.setImageResource(R.mipmap.ic_launcher);
        viewHolder.tvBookName.setText(book.getTitle());
        viewHolder.tvBookSub.setText(book.getSub());
        viewHolder.tvBookAuthor.setText(book.getAuthor());
        viewHolder.tvBookReading.setText(book.getReading());
        return view;
    }
    private static class ViewHolder {
        ImageView imgBook;
        TextView tvBookName;
        TextView tvBookSub;
        TextView tvBookAuthor;
        TextView tvBookReading;
        ViewHolder(View view) {
            do....findViewById...
        }
    }
}

Book

public class Book implements Serializable{
    private int id;
    private String img;//封面
    private int img1;
    private String title;//书名
    private String sub;//简介
    private String author;
    private String reading;//阅读人数
    private String online;
    private String bytime;//上线时间
    do...get...
    do...set...
}

HttpManager

class HttpManager {
    private static LoadBookListener mListener;
    interface LoadBookListener {
        void onLoadBooksEnd(List books);
    }
    static void asyncBooks(LoadBookListener listener) {
        //罪魁祸首在这!!!!!!!
        if (mListener == null) {
            mListener = listener;
        }
        AsyncBooksTask task = new AsyncBooksTask();
        task.execute();
    }
    private static class AsyncBooksTask extends AsyncTask> {
        @Override
        protected List doInBackground(Void... params) {
            List books = new ArrayList<>();
            return getBooks(books);
        }
        @Override
        protected void onPostExecute(List books) {
            listener.onLoadBooksEnd(books);
        }
    }
    private static List getBooks(List books) {
        for (int i = 0; i < 12; i++) {
            String title = "title" + i;
            String author = "author" + i;
            String sub = "sub" + i;
            String img = "img" + i;
            String reading = "reading" + i;
            String online = "online" + i;
            String byTime = "byTime" + i;
            Book book = new Book(i + 1, img, title, sub, author, reading, online, byTime);
            books.add(book);
        }
        return books;
    }
}