如何在 RecyclerView OnClickListener 中管理多个位置

Question

I want to know how I can get access to other elements of the array in this onclicklistener for a Recycler view. Specifically, I want to be able to change the enabled state of a position other than the current Listener position, but within the click event.

I'm trying to make it such that if three colors are checked (those are check boxes) every box not checked will be disabled until the number of boxes checked is < 3.

The for-loops I have I wrote make sense, but I can't programmatically change the enabled state within the onClickListener for some reason.

  private void buildRecyclerView() {

            mRecyclerView = findViewById(R.id.recyclerView);
            mRecyclerView.setHasFixedSize(true);
            mLayoutManager = new LinearLayoutManager(this);
            mAdapter = new ExampleAdapter(mExampleList);

            mRecyclerView.setLayoutManager(mLayoutManager);
            mRecyclerView.setAdapter(mAdapter);

            mAdapter.setOnItemClickListener(new ExampleAdapter.OnItemClickListener() {
                @Override
                public void onItemClick(int position) {

                    boolean checkedState;

                    if (mExampleList.get(position).getChecked1() == false) {

                        checkedState = true;

                    } else {

                        checkedState = false;

                    }

                    changeItem(position, checkedState);

                    int sum = 0;

                    for (int i = 0; i < stringArray.length; i++) {

                        Boolean checked = mExampleList.get(i).getChecked1();

                        if (checked == true) {

                            sum = sum + 1;

                        }

                    }

                    for (int i = 0; i < stringArray.length; i++) {

                        Boolean checked = mExampleList.get(i).getChecked1();

                        if (!checked && sum == 3) {

                            mExampleList.get(i).setEnabled1(false);

                        } else {

                            mExampleList.get(i).setEnabled1(true);

                        }

                    }

                }

            });

        }

adapter

public class ExampleAdapter extends RecyclerView.Adapter<ExampleAdapter.ExampleViewHolder> {

    private ArrayList<ExampleItem> mExampleList;
    private OnItemClickListener mListener;

    public interface OnItemClickListener {

        void onItemClick(int position);

    }

    public void setOnItemClickListener(OnItemClickListener listener) {

        mListener = listener;

    }

    public static class ExampleViewHolder extends RecyclerView.ViewHolder {

        public CheckBox mCheckBox;

        public ExampleViewHolder(@NonNull View itemView, final OnItemClickListener listener) {
            super(itemView);

            mCheckBox = itemView.findViewById(R.id.checkBox);

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

                    if (listener != null){

                        int position = getAdapterPosition();

                        if (position != RecyclerView.NO_POSITION);
                        listener.onItemClick(position);

                    }

                }
            });

        }
    }

    public ExampleAdapter(ArrayList<ExampleItem> exampleList) {

        mExampleList = exampleList;

    }

    @NonNull
    @Override
    public ExampleViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.example_item, parent, false);
        ExampleViewHolder evh = new ExampleViewHolder(v, mListener);
        return evh;

    }

    @Override
    public void onBindViewHolder(@NonNull ExampleViewHolder holder, int position) {

        ExampleItem currentItem = mExampleList.get(position);

        holder.mCheckBox.setText(currentItem.getCheckText());
        holder.mCheckBox.setEnabled(currentItem.getEnabled1());
        holder.mCheckBox.setChecked(currentItem.getChecked1());

    }

    @Override
    public int getItemCount() {

        return mExampleList.size();

    }
}

Item Class

public class ExampleItem {

    public String mCheckText;
    public Boolean mEnabled;
    public Boolean mChecked;

    public ExampleItem(String mCheckText, Boolean mEnabled, Boolean mChecked) {

        this.mCheckText = mCheckText;
        this.mEnabled = mEnabled;
        this.mChecked = mChecked;
    }

    public ExampleItem(String mCheckText) {
        this.mCheckText = mCheckText;
    }

    public String getCheckText() {
        return mCheckText;
    }

    public void setCheckText(String mCheckText) {
        this.mCheckText = mCheckText;
    }

    public Boolean getEnabled1() {
        return mEnabled;
    }

    public void setEnabled1(Boolean mEnabled) {
        this.mEnabled = mEnabled;
    }

    public Boolean getChecked1() {
        return mChecked;
    }

    public void setChecked1(Boolean mChecked) {
        this.mChecked = mChecked;
    }

}

In other words, I am trying to make everything below blue disabled until I uncheck Red, Green, or Blue!

Answer 1

You would need to create a setter function for your 'mExampleList' in your Adpater class, to update the dataset that the adapter is using. It obviously does not change anything, if you make changes to 'mExampleList' in your activity, without updating the list used by the Adapter.

So at the end of your click listener you would have something like that:

mAdapter.setExampleList(mExampleList)
mAdapter.notifyDataSetChanged()

Answer 2

Try the following:

In adapter, add below codes:

private int selectedCount = 0;

public int getSelectedCount() {
    return selectedCount;
}

public void setSelectedCount(int selectedCount) {
    this.selectedCount = selectedCount;
    notifyDataSetChanged();
}

and change onBindViewHolder() to:

@Override
public void onBindViewHolder(@NonNull ExampleViewHolder holder, int position) {

    ExampleItem currentItem = mExampleList.get(position);

    holder.mCheckBox.setText(currentItem.getCheckText());
    holder.mCheckBox.setChecked(currentItem.getChecked1());
    if ((selectedCount == 3)) holder.mCheckBox.setEnabled(currentItem.getChecked1());
    else holder.mCheckBox.setEnabled(true);
}

Then in Activity/Fragment, change mAdapter.setOnItemClickListener(new ExampleAdapter.OnItemClickListener()... to:

    mAdapter.setOnItemClickListener(new ExampleAdapter.OnItemClickListener() {
        @Override
        public void onItemClick(int position) {
            boolean checkedState;
            int selectedCount = mAdapter.getSelectedCount();

            if ((selectedCount != 3) || (mExampleList.get(position).getChecked1())) {
                if (mExampleList.get(position).getChecked1() == false) {
                    checkedState = true;
                    selectedCount++;
                } else {
                    checkedState = false;
                    selectedCount--;
                }
                changeItem(position, checkedState);
                mAdapter.setSelectedCount(selectedCount);
            }
        }
    });

Pls note that no need to have mEnabled field in the ExampleItem class. Hope that helps!

Explanantion: About the onClick:- This is because CheckBox totally covered the layout, so itemView cannot recieve the click event. About RecyclerView:- The idea is simple, after modified the data set [not list, here I refer to the mExampleList and also the selectedCount], then call notifyDataSetChanged() which will redraw all recycler item views.