在 Recycler 视图中滚动时复选框状态不断变化
CheckBox States Keep Changing While Scrolling in Recycler View
我正在尝试为我的大学制作一个考勤应用程序。我在 Recycler View 中使用 CardView。在我的 Card View 中有一个复选框，用于标记特定学生的出勤情况。问题是，如果我标记说，学生 1,2 和 3。位置 10,11,12 或其他任何东西（随机）上的一些随机卡片会自行标记。我知道这是因为回收站视图回收了这些卡片的位置，但不幸的是，由于我是开发新手，我不知道如何实现复选框来给我检查卡片的详细信息，以便我可以使用它。我已经阅读了一些指南，但一直无法理解。我在下面附加了我的适配器 Class 和 takeAttendance Activity。我还没有实现任何与复选框相关的东西，需要同样的指导。
回收器视图适配器 CLASS
package com.pkg.attendanceapp;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.google.android.material.checkbox.MaterialCheckBox;
import com.google.android.material.textview.MaterialTextView;
import java.util.ArrayList;
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.StudentListViewHolder> {
private ArrayList<StudentList> studentList;
private ArrayList<String> presentStudents;
private ArrayList<StudentList> absentStudents;
public static class StudentListViewHolder extends RecyclerView.ViewHolder {
private MaterialTextView studentName;
private MaterialTextView studentRoll;
private MaterialTextView attendanceTextview;
private MaterialCheckBox checkBox;
public StudentListViewHolder(@NonNull final View itemView) {
super(itemView);
studentName = itemView.findViewById(R.id.stdName);
studentRoll = itemView.findViewById(R.id.stdRoll);
checkBox = itemView.findViewById(R.id.checkBox);
attendanceTextview = itemView.findViewById(R.id.studentAttendance);
}
}
public RecyclerViewAdapter(ArrayList<StudentList> mStudentList){
studentList = mStudentList;
absentStudents = mStudentList;
}
@Override
public StudentListViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return new StudentListViewHolder(LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_view, parent, false));
}
@Override
public void onBindViewHolder(@NonNull final StudentListViewHolder holder, int position) {
StudentList currentStudent = studentList.get(position);
holder.studentName.setText(currentStudent.getStudName());
holder.studentRoll.setText(currentStudent.getStudRoll());
}
@Override
public int getItemCount() {
return studentList == null ? 0 : studentList.size();
}
}
ACTIVITY
package com.pkg.attendanceapp;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.DialogInterface;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.RadioGroup;
import android.widget.Toast;
import com.google.android.gms.tasks.Task;
import com.google.android.material.card.MaterialCardView;
import com.google.android.material.dialog.MaterialAlertDialogBuilder;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.textview.MaterialTextView;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;
public class takeAttendance extends AppCompatActivity {
DatabaseReference AttendanceDatabaseReference;
private RecyclerView recyclerView;
private RecyclerViewAdapter recyclerViewAdapter;
public ArrayList<StudentList> studentListArray;
//private String date = new SimpleDateFormat("dd-MM-yyyy", Locale.getDefault()).format(new Date());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_take_attendance);
//FloatingActionButton saveBtn = findViewById(R.id.floatingActionButton);
recyclerView = findViewById(R.id.mRecyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setHasFixedSize(true);
recyclerViewAdapter = new RecyclerViewAdapter(studentListArray);
recyclerView.setAdapter(recyclerViewAdapter);
studentListArray = new ArrayList<>();
AttendanceDatabaseReference = FirebaseDatabase.getInstance().getReference("studentsInfo");
AttendanceDatabaseReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull final DataSnapshot dataSnapshot) {
findViewById(R.id.progressBar).setVisibility(View.GONE);
for (DataSnapshot mDataSnapshot : dataSnapshot.getChildren()){
StudentList studentsList = mDataSnapshot.getValue(StudentList.class);
studentListArray.add(studentsList);
}
recyclerViewAdapter = new RecyclerViewAdapter(studentListArray);
recyclerView.setAdapter(recyclerViewAdapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
// Toast.makeText(takeAttendance.this, "Oops! Something Went Wrong...", Toast.LENGTH_LONG).show();
}
});
}
}
我之前遇到过这个问题，解决方案是您必须保存模型中每个复选框的布尔值 class，如果选中则为 true，否则为 false。
基于其他 Posts/Guides，它是这样工作的 -
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
private ArrayList<StudentList> studentList;
private ArrayList<String> mRollNum;
private Activity activity;
private OnCheckBoxClickListener mListener;
private SparseBooleanArray itemStateArray = new SparseBooleanArray();
public interface OnCheckBoxClickListener {
void onCheckBoxClick(int position, boolean isChecked);
}
void setOnCheckBoxClickListener(OnCheckBoxClickListener listener){
mListener = listener;
}
class ViewHolder extends RecyclerView.ViewHolder {
private MaterialTextView studentName;
private MaterialTextView studentRoll;
private MaterialTextView attendanceStatus;
MaterialCheckBox mCheckbox;
ViewHolder(@NonNull View itemView, final OnCheckBoxClickListener listener) {
super(itemView);
studentName = itemView.findViewById(R.id.stdName);
studentRoll = itemView.findViewById(R.id.stdRoll);
attendanceStatus = itemView.findViewById(R.id.studentAttendance);
mCheckbox = itemView.findViewById(R.id.checkBox);
mCheckbox.setOnClickListener(new View.OnClickListener() {
@SuppressLint("SetTextI18n")
@Override
public void onClick(View view) {
int adapterPosition = getAdapterPosition();
if (!itemStateArray.get(adapterPosition, false)) {
attendanceStatus.setTextColor(Color.GREEN);
attendanceStatus.setText("Present");
mCheckbox.setChecked(true);
itemStateArray.put(adapterPosition, true);
listener.onCheckBoxClick(adapterPosition, true);
}
else {
mCheckbox.setChecked(false);
itemStateArray.put(adapterPosition, false);
listener.onCheckBoxClick(adapterPosition, false);
attendanceStatus.setTextColor(Color.RED);
attendanceStatus.setText("Absent");
}
}
});
}
@SuppressLint("SetTextI18n")
void bind(int position) {
if (!itemStateArray.get(position, false)) {
mCheckbox.setChecked(false);
attendanceStatus.setTextColor(Color.RED);
attendanceStatus.setText("Absent");
}
else {
attendanceStatus.setTextColor(Color.GREEN);
attendanceStatus.setText("Present");
mCheckbox.setChecked(true);
}
}
}
RecyclerViewAdapter(Activity activity, ArrayList<StudentList> mStudentList, ArrayList<String> rollNum ) {
studentList = mStudentList;
this.activity = activity;
this.mRollNum = rollNum;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View studentListView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_view, parent, false);
return new ViewHolder(studentListView, mListener);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
StudentList currentStudent = studentList.get(position);
holder.studentName.setText(currentStudent.getStudName());
holder.studentRoll.setText(currentStudent.getStudRoll());
holder.bind(position);
}
@Override
public int getItemCount() {
return studentList == null ? 0 : studentList.size();
}
我正在尝试为我的大学制作一个考勤应用程序。我在 Recycler View 中使用 CardView。在我的 Card View 中有一个复选框，用于标记特定学生的出勤情况。问题是，如果我标记说，学生 1,2 和 3。位置 10,11,12 或其他任何东西（随机）上的一些随机卡片会自行标记。我知道这是因为回收站视图回收了这些卡片的位置，但不幸的是，由于我是开发新手，我不知道如何实现复选框来给我检查卡片的详细信息，以便我可以使用它。我已经阅读了一些指南，但一直无法理解。我在下面附加了我的适配器 Class 和 takeAttendance Activity。我还没有实现任何与复选框相关的东西，需要同样的指导。
回收器视图适配器 CLASS
package com.pkg.attendanceapp;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.google.android.material.checkbox.MaterialCheckBox;
import com.google.android.material.textview.MaterialTextView;
import java.util.ArrayList;
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.StudentListViewHolder> {
private ArrayList<StudentList> studentList;
private ArrayList<String> presentStudents;
private ArrayList<StudentList> absentStudents;
public static class StudentListViewHolder extends RecyclerView.ViewHolder {
private MaterialTextView studentName;
private MaterialTextView studentRoll;
private MaterialTextView attendanceTextview;
private MaterialCheckBox checkBox;
public StudentListViewHolder(@NonNull final View itemView) {
super(itemView);
studentName = itemView.findViewById(R.id.stdName);
studentRoll = itemView.findViewById(R.id.stdRoll);
checkBox = itemView.findViewById(R.id.checkBox);
attendanceTextview = itemView.findViewById(R.id.studentAttendance);
}
}
public RecyclerViewAdapter(ArrayList<StudentList> mStudentList){
studentList = mStudentList;
absentStudents = mStudentList;
}
@Override
public StudentListViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
return new StudentListViewHolder(LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_view, parent, false));
}
@Override
public void onBindViewHolder(@NonNull final StudentListViewHolder holder, int position) {
StudentList currentStudent = studentList.get(position);
holder.studentName.setText(currentStudent.getStudName());
holder.studentRoll.setText(currentStudent.getStudRoll());
}
@Override
public int getItemCount() {
return studentList == null ? 0 : studentList.size();
}
}
ACTIVITY
package com.pkg.attendanceapp;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import android.content.DialogInterface;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.RadioGroup;
import android.widget.Toast;
import com.google.android.gms.tasks.Task;
import com.google.android.material.card.MaterialCardView;
import com.google.android.material.dialog.MaterialAlertDialogBuilder;
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.textview.MaterialTextView;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.ValueEventListener;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;
public class takeAttendance extends AppCompatActivity {
DatabaseReference AttendanceDatabaseReference;
private RecyclerView recyclerView;
private RecyclerViewAdapter recyclerViewAdapter;
public ArrayList<StudentList> studentListArray;
//private String date = new SimpleDateFormat("dd-MM-yyyy", Locale.getDefault()).format(new Date());
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_take_attendance);
//FloatingActionButton saveBtn = findViewById(R.id.floatingActionButton);
recyclerView = findViewById(R.id.mRecyclerView);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setHasFixedSize(true);
recyclerViewAdapter = new RecyclerViewAdapter(studentListArray);
recyclerView.setAdapter(recyclerViewAdapter);
studentListArray = new ArrayList<>();
AttendanceDatabaseReference = FirebaseDatabase.getInstance().getReference("studentsInfo");
AttendanceDatabaseReference.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull final DataSnapshot dataSnapshot) {
findViewById(R.id.progressBar).setVisibility(View.GONE);
for (DataSnapshot mDataSnapshot : dataSnapshot.getChildren()){
StudentList studentsList = mDataSnapshot.getValue(StudentList.class);
studentListArray.add(studentsList);
}
recyclerViewAdapter = new RecyclerViewAdapter(studentListArray);
recyclerView.setAdapter(recyclerViewAdapter);
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
// Toast.makeText(takeAttendance.this, "Oops! Something Went Wrong...", Toast.LENGTH_LONG).show();
}
});
}
}
我之前遇到过这个问题，解决方案是您必须保存模型中每个复选框的布尔值 class，如果选中则为 true，否则为 false。
基于其他 Posts/Guides，它是这样工作的 -
public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {
private ArrayList<StudentList> studentList;
private ArrayList<String> mRollNum;
private Activity activity;
private OnCheckBoxClickListener mListener;
private SparseBooleanArray itemStateArray = new SparseBooleanArray();
public interface OnCheckBoxClickListener {
void onCheckBoxClick(int position, boolean isChecked);
}
void setOnCheckBoxClickListener(OnCheckBoxClickListener listener){
mListener = listener;
}
class ViewHolder extends RecyclerView.ViewHolder {
private MaterialTextView studentName;
private MaterialTextView studentRoll;
private MaterialTextView attendanceStatus;
MaterialCheckBox mCheckbox;
ViewHolder(@NonNull View itemView, final OnCheckBoxClickListener listener) {
super(itemView);
studentName = itemView.findViewById(R.id.stdName);
studentRoll = itemView.findViewById(R.id.stdRoll);
attendanceStatus = itemView.findViewById(R.id.studentAttendance);
mCheckbox = itemView.findViewById(R.id.checkBox);
mCheckbox.setOnClickListener(new View.OnClickListener() {
@SuppressLint("SetTextI18n")
@Override
public void onClick(View view) {
int adapterPosition = getAdapterPosition();
if (!itemStateArray.get(adapterPosition, false)) {
attendanceStatus.setTextColor(Color.GREEN);
attendanceStatus.setText("Present");
mCheckbox.setChecked(true);
itemStateArray.put(adapterPosition, true);
listener.onCheckBoxClick(adapterPosition, true);
}
else {
mCheckbox.setChecked(false);
itemStateArray.put(adapterPosition, false);
listener.onCheckBoxClick(adapterPosition, false);
attendanceStatus.setTextColor(Color.RED);
attendanceStatus.setText("Absent");
}
}
});
}
@SuppressLint("SetTextI18n")
void bind(int position) {
if (!itemStateArray.get(position, false)) {
mCheckbox.setChecked(false);
attendanceStatus.setTextColor(Color.RED);
attendanceStatus.setText("Absent");
}
else {
attendanceStatus.setTextColor(Color.GREEN);
attendanceStatus.setText("Present");
mCheckbox.setChecked(true);
}
}
}
RecyclerViewAdapter(Activity activity, ArrayList<StudentList> mStudentList, ArrayList<String> rollNum ) {
studentList = mStudentList;
this.activity = activity;
this.mRollNum = rollNum;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View studentListView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.card_view, parent, false);
return new ViewHolder(studentListView, mListener);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
StudentList currentStudent = studentList.get(position);
holder.studentName.setText(currentStudent.getStudName());
holder.studentRoll.setText(currentStudent.getStudRoll());
holder.bind(position);
}
@Override
public int getItemCount() {
return studentList == null ? 0 : studentList.size();
}