Java 如何在android Studio中对Recylcerview中的名称应用字母排序
我有一个学生跟踪应用程序,它使用Java 如何在android Studio中对Recylcerview中的名称应用字母排序,java,android,firebase,android-studio,Java,Android,Firebase,Android Studio,我有一个学生跟踪应用程序,它使用firebase作为后端。我现在想做的是,单击Order students按钮后,能够按姓名对学生进行排序。现在我有一个方法,可以使用按钮上附带的比较器对学生的姓名进行排序。我验证了它实际上是在排序完成后通过附加println语句进行排序的。现在,我试图找出如何将此逻辑应用于显示学生图像和姓名的RecyclerView。我将在下面发布相关代码。谢谢大家 所以流看起来是这样的 编辑 我已经在下面发布了RecyclerAdapter类的代码 activity\u vi
firebase
作为后端。我现在想做的是,单击Order students
按钮后,能够按姓名对学生进行排序。现在我有一个方法,可以使用按钮上附带的比较器对学生的姓名进行排序。我验证了它实际上是在排序完成后通过附加println语句进行排序的。现在,我试图找出如何将此逻辑应用于显示学生图像和姓名的RecyclerView。我将在下面发布相关代码。谢谢大家
所以流看起来是这样的
编辑
我已经在下面发布了RecyclerAdapter类的代码
activity\u view\u students.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ViewStudents">
<Button
android:id="@+id/addStudentButton"
android:layout_width="50dp"
android:layout_height="50dp"
android:text="Add a Student"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="409dp"
android:layout_height="729dp"
android:layout_marginEnd="1dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" >
</androidx.recyclerview.widget.RecyclerView>
<Button
android:id="@+id/orderStudents"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="orderStudents"
android:text="Order Students"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
RecycleAdapter.class
public class ViewStudents extends AppCompatActivity {
RecyclerView recyclerView;
Button addStudent;
private DatabaseReference myRef;
public ArrayList<Students> students;
private RecyclerAdapter recyclerAdapter;
private Button orderStudents;
private EditText mEditTextAge;
private EditText mEditTextAssignment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_view_students);
recyclerView = findViewById(R.id.recyclerView);
addStudent = findViewById(R.id.addStudentButton);
mEditTextAge = findViewById(R.id.EditTextAge);
mEditTextAssignment = findViewById(R.id.EditTextAssignment);
orderStudents = findViewById(R.id.orderStudents);
addStudent.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
startActivity(new Intent(ViewStudents.this, AddStudent.class));
}
});
recyclerView.setLayoutManager(new GridLayoutManager(this, 2));
recyclerView.setHasFixedSize(true);
myRef = FirebaseDatabase.getInstance().getReference();
students = new ArrayList<>();
ClearAll();
GetDataFromFirebase();
}
// This method will make a call to firebase and get names and
// images of the students in the db
private void GetDataFromFirebase() {
Query query = myRef.child("student");
query.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
ClearAll();
for(DataSnapshot snapshot: dataSnapshot.getChildren()) {
Students student = new Students();
if (snapshot.child("url").getValue() == null) {
student.setImageUrl(snapshot.child("imageUrl").getValue().toString());
}
else {
student.setImageUrl(snapshot.child("url").getValue().toString());
}
// student.setAge(mEditTextAge.getText().toString());
// student.setAssignment(mEditTextAssignment.getText().toString().trim());
student.setName(snapshot.child("name").getValue().toString());
students.add(student);
}
recyclerAdapter = new RecyclerAdapter(getApplicationContext(), students);
recyclerView.setAdapter(recyclerAdapter);
recyclerAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(@NonNull DatabaseError databaseError) {
}
});
}
// will clear any pre-existing data
private void ClearAll() {
if (students != null) {
students.clear();
if(recyclerAdapter != null) {
recyclerAdapter.notifyDataSetChanged();
}
}
students = new ArrayList<>();
}
// method to order students by name
public void orderStudents(View view) {
Intent orderIntent = new Intent(this, ViewStudents.class);
startActivity(orderIntent);
orderStudents.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Collections.sort(students, new Comparator<Students>() {
@Override
public int compare(Students o1, Students o2) {
return o1.name.compareTo(o2.name);
}
});
}
});
for(int i = 0; i < students.size(); i++){
System.out.println("Students ==> " + students.get(i).getName());
}
}
package com.example.studenttracker;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import com.bumptech.glide.Glide;
import java.util.ArrayList;
public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> {
private OnItemClickListener mListener;
public interface OnItemClickListener {
void onItemClick(int position);
}
public void setOnItemClickListener(OnItemClickListener listener) {
mListener = listener;
}
private static final String Tag = "RecyclerView";
private Context mContext;
private ArrayList<Students> studentsArrayList;
public RecyclerAdapter(Context mContext, ArrayList<Students> studentsArrayList) {
this.mContext = mContext;
this.studentsArrayList = studentsArrayList;
}
@NonNull
@Override
public RecyclerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.student_item,parent,false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
//TextView
holder.textView.setText(studentsArrayList.get(position).getName());
Glide.with(mContext).load(studentsArrayList.get(position).getImageUrl()).into(holder.imageView);
}
@Override
public int getItemCount() {
return studentsArrayList.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
ImageView imageView;
TextView textView;
public ViewHolder(@NonNull View itemView) {
super(itemView);
imageView = itemView.findViewById(R.id.imageView);
textView = itemView.findViewById(R.id.textView);
itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mListener != null) {
int position = getAdapterPosition();
}
}
});
}
}
}
package com.example.studenttracker;
导入android.content.Context;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.widget.ImageView;
导入android.view.ViewGroup;
导入android.widget.ImageView;
导入android.widget.TextView;
导入androidx.annotation.NonNull;
导入androidx.recyclerview.widget.recyclerview;
导入com.bumptech.glide.glide;
导入java.util.ArrayList;
公共类RecyclerAdapter扩展了RecyclerView.Adapter{
私人监听者;
公共接口侦听器{
无效单击(内部位置);
}
公共void setOnItemClickListener(OnItemClickListener侦听器){
mListener=监听器;
}
私有静态最终字符串Tag=“RecyclerView”;
私有上下文;
私立ArrayList学生名单;
公共回收器适配器(上下文mContext、ArrayList studentsArrayList){
this.mContext=mContext;
this.studentsArrayList=studentsArrayList;
}
@非空
@凌驾
public RecyclerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup父级,int-viewType){
View=LayoutInflater.from(parent.getContext())
.充气(右布局、学生项、家长、假);
返回新的ViewHolder(视图);
}
@凌驾
public void onBindViewHolder(@NonNull ViewHolder,int位置){
//文本视图
holder.textView.setText(studentsArrayList.get(position.getName());
Glide.with(mContext).load(studentsArrayList.get(position.getImageUrl())到(holder.imageView)中;
}
@凌驾
public int getItemCount(){
return studentsArrayList.size();
}
公共类ViewHolder扩展了RecyclerView.ViewHolder{
图像视图图像视图;
文本视图文本视图;
公共视图持有者(@NonNull View itemView){
超级(项目视图);
imageView=itemView.findViewById(R.id.imageView);
textView=itemView.findViewById(R.id.textView);
itemView.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
if(mListener!=null){
int position=getAdapterPosition();
}
}
});
}
}
}
将您的RecyclerAdapter更改为扩展ListAdapter
,然后您可以让您的orderStudents
单击方法修改适配器中的列表,例如:
// method to order students by name
public void orderStudents(View view) {
Intent orderIntent = new Intent(this, ViewStudents.class);
startActivity(orderIntent);
orderStudents.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
List<Students> l = recyclerAdapter.getCurrentList();
Collections.sort(l, new Comparator<Students>() {
@Override
public int compare(Students o1, Students o2) {
return o1.name.compareTo(o2.name);
}
});
recyclerAdapter.submitList( l );
}
});
//按姓名对学生排序的方法
公共学生(视图){
Intent orderIntent=新的Intent(这个,viewstustudents.class);
startActivity(orderIntent);
orderStudents.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
List l=recyclerAdapter.getCurrentList();
Collections.sort(l,新的Comparator(){
@凌驾
公共整数比较(学生o1,学生o2){
返回o1.name.compareTo(o2.name);
}
});
回收器适配器提交列表(l);
}
});
将您的RecyclerAdapter更改为扩展ListAdapter
,然后您可以让您的orderStudents
单击方法修改适配器中的列表,例如:
// method to order students by name
public void orderStudents(View view) {
Intent orderIntent = new Intent(this, ViewStudents.class);
startActivity(orderIntent);
orderStudents.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
List<Students> l = recyclerAdapter.getCurrentList();
Collections.sort(l, new Comparator<Students>() {
@Override
public int compare(Students o1, Students o2) {
return o1.name.compareTo(o2.name);
}
});
recyclerAdapter.submitList( l );
}
});
//按姓名对学生排序的方法
公共学生(视图){
Intent orderIntent=新的Intent(这个,viewstustudents.class);
startActivity(orderIntent);
orderStudents.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
List l=recyclerAdapter.getCurrentList();
Collections.sort(l,新的Comparator(){
@凌驾
公共整数比较(学生o1,学生o2){
返回o1.name.compareTo(o2.name);
}
});
回收器适配器提交列表(l);
}
});
Post yourRecyclerAdapter
code,您可能可以在那里的某个地方对列表进行排序,但不知道您是如何构建的,我无法建议在哪里。我已经发布了RecyclerAdapter
Post yourRecyclerAdapter
代码的代码,您可能可以在那里的某个地方对列表进行排序,但不知道您是如何创建的我已经发布了RecylcAdapter
的代码,我想点击按钮Order Students
,然后按名称排序。不是在它打电话从firebase获取数据时。啊,好的,更改了我的答案。扩展ListAdapter
将允许您获取并设置列表适配器正在使用。非常感谢@Ralgha你救了我一天!我想单击按钮为学生排序,然后按名称排序。不是在它打电话从firebase获取数据时。啊,好的,更改了我的答案。扩展列表适配器将允许你获取和设置适配器正在使用的列表。Tha谢谢你@Ra