Android Recycler+CardView with Icon and Spinner - 排序问题

Question

所以我现在的申请遇到了更大的问题。

首先让我总结一下整体设置:

我正在为我的数据库使用 Room，我的实体称为 Sub - 一列是关于“numUsage”(使用次数)的。 Activity 的 UI 是一个带有 CardView 的 RecyclerView - 更好的说法是每行两张卡片加一个心形图标。

• 第一张卡片:显示子名
• 第二张卡片:显示 Sub 的使用次数
• 心形图标:如果点击这个图标，它应该变成一个充满心形的心形(如 Instagram)并计算其 Sub 的使用点数(这个想法也是让它每天只能点击一次，这是一个 future 的问题)

在顶部，我有一个微调器，让用户可以对他获得的列表进行“排序”。他可以在“entry”(按照 Subs 如何进入数据库的顺序)、“top”(numUsage DESC)和“flop”(numUsage ASC)之后对其进行排序

排序本身通过数据库中的 DAO 发生，但是微调器的选择是， Activity 调用“合适的”DAO(在下面的代码中显示)。

排序有效。此外，每当我点击 Sub 的心形图标时，numUsage 就会加一，实体也会更新。

现在我们来解决问题:当我点击心形图标时，它会发生变化(就像我想要的那样) - 但是当我现在将微调器设置为另一种“排序方式”(例如从“入口”到“顶部”)时，两个 CardViews 更新/排序但心形图标保持在完全相同的位置(但它也应该移动，因为我想看看哪个 Sub 已经计数了)

我知道这是因为我实际上并没有对卡片进行排序，而只是将数据从数据库中取出并编写新卡片的方式(因此心形图标保持在其原始位置)。但我只是错过了如何解决这个问题的正确想法。

如果你能帮助我，那就太棒了!

---

这是一张小图来说明我的问题:

---

子DAO:

//Get all subs
@Query("SELECT * FROM subscriptions")
LiveData<List<Sub>> getAllSubs();

//Get sub with less used points (=worst/flop Sub)
@Query("SELECT * FROM subscriptions ORDER BY numUsage ASC")
LiveData<List<Sub>> getAllFlopSubs();

//Get sub with most used points (=top Sub)
@Query("SELECT * FROM subscriptions ORDER BY numUsage DESC")
LiveData<List<Sub>> getAllTopSubs();

---

UsageActivity - 微调器会发生什么:

@Override
public void onItemSelected(AdapterView<?> parent, View v, int position, long id){
    switch (position){
        case 0:
            ((TextView) parent.getChildAt(0)).setTextColor(getResources().getColor(R.color.midBlue));
            setupListViewEntry();
            break;
        case 1:
            ((TextView) parent.getChildAt(0)).setTextColor(getResources().getColor(R.color.midBlue));
            setupListViewTop();
            break;
        case 2:
            ((TextView) parent.getChildAt(0)).setTextColor(getResources().getColor(R.color.midBlue));
            setupListViewFlop();
            break;

    }
}


@Override
public void onNothingSelected(AdapterView<?> arg0){
    setupListViewEntry();
}






private void setupListViewEntry() {
    mSubViewModel.getAllSubs().observe(this, new Observer<List<Sub>>() {
        @Override
        public void onChanged(@Nullable List<Sub> subs) {
            mAdapter.setSubs(subs);

        }
    });
}






private void setupListViewTop() {
    mSubViewModel.getAllTopSubs().observe(this, new Observer<List<Sub>>() {
        @Override
        public void onChanged(@Nullable List<Sub> subs) {
            mAdapter.setSubs(subs);

        }
    });
}






private void setupListViewFlop() {
    mSubViewModel.getAllFlopSubs().observe(this, new Observer<List<Sub>>() {
        @Override
        public void onChanged(@Nullable List<Sub> subs) {
            mAdapter.setSubs(subs);

        }
    });
}

---

使用适配器:

公共(public)类 UsageSubAdapter 扩展 RecyclerView.Adapter{

List<Sub> subList;
Context context;
private final LayoutInflater mInflater;

UsageSubAdapter (Context context) {
    mInflater = LayoutInflater.from(context);
}


public class ViewHolder extends  RecyclerView.ViewHolder {
    public TextView subUsage_name_cv_dummy;
    public TextView subUsage_times_cv_dummy;
    public View clickable;
    public ImageView plus_usage;
    public ViewHolder(View itemView) {
        super(itemView);
        subUsage_name_cv_dummy = itemView.findViewById(R.id.usage_name_dummy);
        subUsage_times_cv_dummy = itemView.findViewById(R.id.usage_times_dummy);
        clickable = itemView.findViewById(R.id.usage_cv_left);
        plus_usage = itemView.findViewById(R.id.usage_like_btn);
    }
}

@Override
public UsageSubAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType){
    View subview = mInflater.inflate(R.layout.cv_usage, parent, false);

    return new UsageSubAdapter.ViewHolder(subview);
}


@Override
public void onBindViewHolder (final UsageSubAdapter.ViewHolder holder, int position) {

    //Set Texts for CardViews
    if (subList!= null){
        final Sub current = subList.get(position);

        holder.subUsage_name_cv_dummy.setText(current.getSubName());
        holder.subUsage_times_cv_dummy.setText(Integer.toString(current.getNumUsage()));

        holder.clickable.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Click on left CV to open up InfoFragment
                ShowInfoFragment currentFrag = ShowInfoFragment.newInstance(current);
                UsageActivity.fragmentManager.beginTransaction().replace(R.id.compLayout, currentFrag).addToBackStack(null).commit();
                Log.d("Clicking: ", current.getSubName() + " was clicked - Listener worked");
            }
        });

        holder.plus_usage.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //Count up usage point
                int currentUsage = current.getNumUsage();
                int newUsage = currentUsage + 1;
                current.setNumUsage(newUsage);
                updateNumUsage(current);

                //change icon so the user knows it was clicked (for today)
                holder.plus_usage.setImageResource(R.drawable.ic_usage_point_given);
                //make it only clickable once a day

            }
        });
    }
    else {
        holder.subUsage_name_cv_dummy.setText("Create a new Sub!");
        holder.subUsage_times_cv_dummy.setText("00");
    }

}



//Updating the number of Usages
private void updateNumUsage (final Sub sub){
    new Thread(new Runnable() {
        @Override
        public void run() {
            Looper.prepare();
            SubDatabase.getInstance(context)
                    .getsubDAO()
                    .updateSub(sub);
        }
    }).start();
}




public void setSubs(List<Sub> subs){
    this.subList = subs;
    notifyDataSetChanged();
}



@Override
public int getItemCount(){
    if(subList!=null){
        return subList.size();
    } else
    {
        return 0;
    }
}

Answer 1

问题是您目前没有存储心形图标的值。如果没有这些信息，您将无法告诉 RecyclerView 如何呈现它。

查看您的 onBindViewHolder，您正在更新名称和计数的值，但不是心脏。您仅在单击时将心设置为 Activity 状态。

final Sub current = subList.get(position);

holder.subUsage_name_cv_dummy.setText(current.getSubName());
holder.subUsage_times_cv_dummy.setText(Integer.toString(current.getNumUsage()));

// TODO - Set the current state of the heart icon.

holder.clickable.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
       // ...
    }
});
holder.plus_usage.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        holder.plus_usage.setImageResource(R.drawable.ic_usage_point_given);
    }
});

您需要做的是保存一个值，并在渲染时使用它。对于此示例，我们假设您已将 boolean isActive = false; 添加到您的 Sub 类。

首先，由于我们需要在两个地方(渲染和 onClick)更新图标，我会创建一个像这样的小函数。

void updateUsageIcon(UsageSubAdapter.ViewHolder holder, Sub sub) {
    if( sub.isActive ) {
        holder.plus_usage.setImageResource(R.drawable.ic_usage_point_given);
    } else {
        // TODO show inactive state
    }
}

然后，在您的 ViewHolder 中，您可以执行类似的操作。

final Sub current = subList.get(position);

holder.subUsage_name_cv_dummy.setText(current.getSubName());
holder.subUsage_times_cv_dummy.setText(Integer.toString(current.getNumUsage()));

// Set the current value.
updateUsageIcon(holder, sub);

holder.plus_usage.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {

        // Add logic to check if the user is allowed to set this to true today.
        sub.isActive = true;

        // Update the current value.
        updateUsageIcon(holder, sub);
    }
});