我无法解决我在RecyclerView中执行CHECKBOX的错误

Question

package com.example.project.Holder;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.request.RequestOptions;
import com.example.project.Model.User;
import com.example.project.R;

import java.util.List;

public class AttendanceViewHolder {

    private Context mContext;
    private UserAdapter userAdapter;


    public void setConfig(RecyclerView recyclerView,Context context,List<User> users,List<String> keys){
        mContext=context;
        userAdapter=new UserAdapter(users,keys);
        recyclerView.setLayoutManager(new LinearLayoutManager(context));
        recyclerView.setAdapter(userAdapter);
    }
    class UserItemView extends RecyclerView.ViewHolder {
        public ImageView attendanceitem_imageview;
        private TextView attendanceitem_textview;
        private String key;
        public CheckBox attendance_checkBox;

        public UserItemView(ViewGroup parent) {
            super(LayoutInflater.from(mContext).
                    inflate(R.layout.item_attendance_bottom, parent, false));
            attendanceitem_imageview = (ImageView) itemView.findViewById(R.id.attendanceitem_imageview);
            attendanceitem_textview = (TextView) itemView.findViewById(R.id.attendanceitem_textview);
            attendance_checkBox =(CheckBox) itemView.findViewById(R.id.attendance_checkBox);
        }

        public void bind(User user, String key) {

            attendanceitem_textview.setText(user.getUsername());

            this.key = key;
        }

    }
    class UserAdapter extends RecyclerView.Adapter<UserItemView> {
             List<User> userList;
            private  List<String> mkeys;

            public UserAdapter(List<User> userList, List<String> mkeys) {
                this.userList = userList;
                this.mkeys = mkeys;


            }

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

                return new UserItemView(parent);
            }

            @Override
            public void onBindViewHolder(@NonNull UserItemView holder, int position) {
                final int pos = position;
                holder.attendance_checkBox.setChecked(userList.get(position).isCheckBox());
                holder.attendance_checkBox.setTag(userList.get(position));
                holder.bind(userList.get(position),mkeys.get(position));
                Glide.with(holder.attendanceitem_imageview.getContext())
                        .load(userList.get(position).profileImageUrl)
                        .apply(new RequestOptions())
                        .into(holder.attendanceitem_imageview);
                holder.attendance_checkBox.setOnClickListener(new View.OnClickListener() {
                    public void onClick(View view) {
                        CheckBox attendance_checkBox = (CheckBox) view;
                        User contact = (User) attendance_checkBox.getTag();

                        contact.setCheckBox(attendance_checkBox.isChecked());
                        userList.get(pos).setCheckBox(attendance_checkBox.isChecked());
                    }
                });
            }

            @Override
            public int getItemCount() {
                return userList.size();
            }
        }
}




package com.example.project.Model;

import android.net.Uri;
import android.widget.ImageView;

public class User {
    public String email;
    public String profileImageUrl;
    public String username;
    public String uid;
    public String pushToken;
    public String job;
    public String comment;
    public Boolean checkBox;

    public User() {
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }


    public String getProfileImageUrl() {
        return profileImageUrl;
    }

    public void setProfileImageUrl(String profileImageUrl) {
        this.profileImageUrl = profileImageUrl;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getUid() {
        return uid;
    }

    public void setUid(String uid) {
        this.uid = uid;
    }

    public String getPushToken() {
        return pushToken;
    }

    public void setPushToken(String pushToken) {
        this.pushToken = pushToken;
    }

    public String getJob() {
        return job;
    }

    public void setJob(String job) {
        this.job = job;
    }

    public String getComment() {
        return comment;
    }

    public void setComment(String comment) {
        this.comment = comment;
    }

    public boolean isCheckBox() {
        return checkBox;
    }

    public void setCheckBox(Boolean chechBox) {
        this.checkBox = chechBox;
    }
}




'''
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.lang.Boolean.booleanValue()' on a null object reference
        at com.example.project.Model.User.isCheckBox(User.java:77)
        at com.example.project.Holder.AttendanceViewHolder$UserAdapter.onBindViewHolder(AttendanceViewHolder.java:80)
        at com.example.project.Holder.AttendanceViewHolder$UserAdapter.onBindViewHolder(AttendanceViewHolder.java:58)
        at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6937)
        at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6979)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5896)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6163)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6002)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5998)
        at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2226)
        at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1558)
        at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1518)
        at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:613)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4033)
        at androidx.recyclerview.widget.RecyclerView.dispatchLayout(RecyclerView.java:3750)
        at androidx.recyclerview.widget.RecyclerView.onLayout(RecyclerView.java:4303)
        at android.view.View.layout(View.java:21927)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
        at android.view.View.layout(View.java:21927)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at android.view.View.layout(View.java:21927)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1829)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1673)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1582)
        at android.view.View.layout(View.java:21927)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:332)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:270)
        at com.android.internal.policy.DecorView.onLayout(DecorView.java:779)
        at android.view.View.layout(View.java:21927)
        at android.view.ViewGroup.layout(ViewGroup.java:6260)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:3080)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2590)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1721)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7598)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:966)
        at android.view.Choreographer.doCallbacks(Choreographer.java:790)
        at android.view.Choreographer.doFrame(Choreographer.java:725)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:951)
        at android.os.Handler.handleCallback(Handler.java:883)
        at android.os.Handler.dispatchMessage(Handler.java:100)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
'''

Answer 1

onClick内的样板代码太多。

仅使用

public void onClick(View view) {
   userList.get(pos).setCheckBox(holder.attendance_checkBox.isChecked());
}

代替

public void onClick(View view) {
    CheckBox attendance_checkBox = (CheckBox) view;
    User contact = (User) attendance_checkBox.getTag();

    contact.setCheckBox(attendance_checkBox.isChecked());
    userList.get(pos).setCheckBox(attendance_checkBox.isChecked());
}

Answer 2

我认为您需要尝试以下代码
用于初始化活动中的适配器

UserAdapter userAdapter = new UserAdapter(MainActivity.this, userList);
recyclerView.setLayoutManager(new LinearLayoutManager(context));
recyclerView.setAdapter(userAdapter); 

，对于UserAdapter来说，

public class UserAdapter extends RecyclerView.Adapter<UserAdapter.Holder> {

private Context mContext;
private List<User> userList;

public UserAdapter(Context mContext, List<User> userList) {
    this.mContext = mContext;
    this.userList = userList;
}

@Override
public Holder onCreateViewHolder(ViewGroup parent, int viewType) {
    View rowView = LayoutInflater.from(mContext).inflate(R.layout.item_attendance_bottom, parent, false);
    return new Holder(rowView);
}

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

    User userModel = userList.get(position);

    if (userModel.isCheckBox()) {
        holder.attendance_checkBox.setChecked(true);
    } else {
        holder.attendance_checkBox.setChecked(false);
    }

    /* further set date to textview*/

}

@Override
public int getItemCount() {
    return userList.size();
}

public class Holder extends RecyclerView.ViewHolder {

    public ImageView attendanceitem_imageview;
    private TextView attendanceitem_textview;
    public CheckBox attendance_checkBox;

    public Holder(View itemView) {
        super(itemView);

        attendanceitem_imageview = (ImageView) itemView.findViewById(R.id.attendanceitem_imageview);
        attendanceitem_textview = (TextView) itemView.findViewById(R.id.attendanceitem_textview);
        attendance_checkBox = (CheckBox) itemView.findViewById(R.id.attendance_checkBox);

        attendance_checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton compoundButton, boolean isChecked) {

                int position = getAdapterPosition();

                User tmpUser = userList.get(getAdapterPosition());

                if (isChecked) {
                    tmpUser.setCheckBox(true);
                    notifyItemChanged(position);

                } else {
                    tmpUser.setCheckBox(false);
                    notifyItemChanged(position);
                }
            }
        });
    }
}
}