Android RecyclerView-在for循环中逐个更新项目imageView可见性

我正在从for循环调用

notifyItemChanged（position）

以设置

ImageViewVisibility=inVisible

，但在

for

循环结束后，所有图像视图都会立即显示。而我希望一次显示/隐藏一个imageView。 我需要做什么来解决这个问题

当前输出：

当for循环结束时，所有图像视图同时可见。（我是说 OnBindviewHolder方法仅在

for

循环结束后调用`

预期输出：

对于为每个索引执行的循环，我想逐个显示/隐藏每一行的imageView（我的意思是

OnBindviewHolder

方法应该在调用每个

for

循环时调用）

我尝试过的：

我尝试了

notifyItemChanged（pos）；

，

notifyDataSetChanged（）；

，

notifyItemInserted（pos）；

，但都没有帮助我获得预期的输出。我也尝试了，但仍然是相同的输出

活动

private List<Multiples> items = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_display_result); 
    recyclerView = (RecyclerView) findViewById(R.id.my_recycler_view); 

    // use a linear layout manager
    layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);

    // specify an adapter (see also next example)
    items.addAll(DataGenerator.getPeopleData(this, of, value));
    mAdapter = new MyAdapter(items);
    recyclerView.setAdapter(mAdapter);


    //----------now give few seconds untill all default data is loaded in the recyclerView----------------
    final Handler handler = new Handler();
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            //--------------Now call for loop on every 2 seconds so that we can hide or show ImageViews in each 2 seconds 
            MyAdapter m= (MyAdapter) mAdapter;
            for (Multiples item : items) {
                Multiples multiples1=items.get(items.indexOf(item));
                multiples1.setImageShow(true);  // set true to hide loop 

                Log.i("ms","----------in activity--------"+items.indexOf(item));

                m.updateItem(item,items.indexOf(item));  // forward each row to adapter to take effect

                try {   // sleep for 2 seconds so that we can see the effect of above code(hide/show imageView for this row index  items.indexOf(item)
                    Log.i("s","#####################  going to sleep #######################"+items.indexOf(item) );
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

        }
    }, 2500);

}

---

您的问题是，您在尝试更改所有可见性时阻塞了主线程。因此，尽管您尝试睡眠以在操作之间设置延迟，但前面的操作无法执行，因为线程被阻塞。换句话说，您正在排队等待所有操作，但在释放主线程之前，这些操作无法生效线程和系统可以处理它们，然后同时发生

public void run() {
    // THIS IS HAPPENING ON THE MAIN THREAD - ANDROID CAN'T CONTINUE DRAWING
    // UNTIL THIS METHOD FINISHES
        //--------------Now call for loop on each 2 seconds so that we can hide or show ImageViews in each 2 seconds 
        MyAdapter m= (MyAdapter) mAdapter;
        for (Multiples item : items) {
            Multiples multiples1=items.get(items.indexOf(item));
            multiples1.setImageShow(true);  // set true to hide loop 

            Log.i("ms","----------in activity--------"+items.indexOf(item));

            m.updateItem(item,items.indexOf(item));  // forward each row to adapter to take effect

            try {   // sleep for 2 seconds so that we can see the effect of above code(hide/show imageView for this row index  items.indexOf(item)
                Log.i("s","#####################  going to sleep #######################"+items.indexOf(item) );

                // THIS SLEEP IS BLOCKING THE MAIN THREAD - ANDROID CAN'T DRAW
                // UNTIL THE OUTER FUNCTION IS DONE
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

    } // THE END OF THE RUN BLOCK - NOW ANDROID CAN RUN THE INSTRUCTIONS THAT
      // HAVE BEEN QUEUED UP, WHICH WILL APPEAR INSTANT

您可以做的一件事是在for循环中启动runnables，就像您已经在使用main函数一样

public void run() {
        //--------------Now call for loop on each 2 seconds so that we can hide or show ImageViews in each 2 seconds 
        MyAdapter m= (MyAdapter) mAdapter;

        int index = 0;
        for (Multiples item : items) {
            // DO NOT SLEEP TO NOT BLOCK THE MAIN THREAD - SCHEDULE WORK FOR LATER INSTEAD
            handler.postDelayed(new Runnabled() {
                Multiples multiples1=items.get(items.indexOf(item));
                multiples1.setImageShow(true);  // set true to hide loop 

                // OTHER LOGIC FOR THIS ITEM HERE

            }, 2000 * index++); // SCHEDULE EACH ITEM TO BE 2 SECONDS LATER THAN THE PREVIOUS
        }
    } // THE LOOP FINISHES INSTANTLY AND DOES NOT BLOCK THE MAIN THREAD

通过这种方式，您可以计划所有更新在您想要的时间发生，并立即释放主线程。稍后，在计划的时间，主线程可以自由处理指令并根据需要制作动画

---

希望这有帮助！

why-ve vote，请写一篇评论谢谢，它根据问题进行。现在，我要写的是，如果我想让TTS阅读每行项目标题，那么现在我想播放基于发言（文本到演讲）的每段文字，而不是时间延迟完成，&一旦TTS播放一行，我就想显示/隐藏图像视图。所以一旦TTS移动到下一行，我就想显示/隐藏下一行的图像视图等。示例：请查看此屏幕截图：我建议创建一个全新的问题（您可以链接到此问题作为参考）而不是试图继续解决这些评论中的不同问题。谢谢！请查看此链接。您可以在这个全新的问题上帮助我：

public void run() {
        //--------------Now call for loop on each 2 seconds so that we can hide or show ImageViews in each 2 seconds 
        MyAdapter m= (MyAdapter) mAdapter;

        int index = 0;
        for (Multiples item : items) {
            // DO NOT SLEEP TO NOT BLOCK THE MAIN THREAD - SCHEDULE WORK FOR LATER INSTEAD
            handler.postDelayed(new Runnabled() {
                Multiples multiples1=items.get(items.indexOf(item));
                multiples1.setImageShow(true);  // set true to hide loop 

                // OTHER LOGIC FOR THIS ITEM HERE

            }, 2000 * index++); // SCHEDULE EACH ITEM TO BE 2 SECONDS LATER THAN THE PREVIOUS
        }
    } // THE LOOP FINISHES INSTANTLY AND DOES NOT BLOCK THE MAIN THREAD