创建卡片时如何在 recyclerview (cardview) 中添加日期。 （卡片创建日期）

Posted 2023-04-19

【中文标题】创建卡片时如何在 recyclerview (cardview) 中添加日期。 （卡片创建日期）

【英文标题】：How to add date in recyclerview (cardview) when the card is created. (Card creation date)

【发布时间】：2020-12-21 10:33:16

【问题描述】：

我正在开发一个便笺应用程序，用户在其中创建便笺，保存便笺后，便笺将保存并显示在回收站视图中。我正在寻找显示创建笔记当天日期的东西。我已经在适配器类中实例化了日历并设置了日期。问题是所有卡片都有今天的日期，而与创建日期无关。如下图所示 Screenshot of emulator

下面是我的适配器类

 package com.cksapp.mvvmarchitecture;
    
    import android.util.Log;
    import android.view.LayoutInflater;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.ImageView;
    import android.widget.PopupMenu;
    import android.widget.TextView;
    
    import androidx.annotation.NonNull;
    import androidx.recyclerview.widget.RecyclerView;
    
    import java.text.DateFormat;
    import java.util.ArrayList;
    import java.util.Calendar;
    import java.util.List;
    
    public class NoteAdapter extends RecyclerView.Adapter<NoteAdapter.NoteHolder> 
    
        private static List<Note> notes = new ArrayList<>();
        private onItemClicklistener listener;
        private onItemClicklistener1 listener1;
        private onItemClicklistener2 listener2;
        private onItemClicklistener3 listener3;
    
        private NoteViewModel noteViewModel;
    
        @NonNull
        @Override
        public NoteHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) 
            View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.note_item,parent,false);
            return new NoteHolder(itemView);
    
        
    
        @Override
        public void onBindViewHolder(@NonNull NoteHolder holder, final int position) 
            final Note currentNote = notes.get(position);
            holder.textViewTitle.setText(currentNote.getTitle());
            holder.textViewDescription.setText(currentNote.getDescription());
            Calendar c = Calendar.getInstance();**//calender instantiation**
            String currentDate = DateFormat.getDateInstance().format(c.getTime());
            holder.textViewdate.setText(currentDate);
    
    
        
        private void deleteItem(int position) 
           noteViewModel.delete(notes.get(position));
        
    
        @Override
        public int getItemCount() 
            return notes.size();
        
    
        public void setNotes(List<Note> notes)
            this.notes = notes;
            notifyDataSetChanged();
        
        public Note getNoteAt(int position)
            return notes.get(position);
        
    
        class NoteHolder extends RecyclerView.ViewHolder
            private TextView textViewTitle, textViewdate;
            private TextView textViewDescription;
            private ImageView menupopup;
    
    
            public NoteHolder(@NonNull View itemView) 
                super(itemView);
                textViewTitle = itemView.findViewById(R.id.text_view_title);
                textViewDescription = itemView.findViewById(R.id.text_view_description);
                textViewdate = itemView.findViewById(R.id.datetext);
                menupopup = itemView.findViewById(R.id.options);
                menupopup.setOnClickListener(new View.OnClickListener() 
                    @Override
                    public void onClick(View v) 
    
                        PopupMenu popupMenu = new PopupMenu(v.getContext(), v);
                        popupMenu.getMenuInflater().inflate(R.menu.popup_menu, popupMenu.getMenu());
                        popupMenu.show();
                        popupMenu.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() 
                            @Override
                            public boolean onMenuItemClick(MenuItem item) 
                                final int position1 = getAdapterPosition();
    
                                switch (item.getItemId())
                                    case R.id.opennotemenu:
                                        if(position1 != RecyclerView.NO_POSITION && listener1 != null) 
                                            listener2.onItemclick2(notes.get(position1));
                                        
                                        break;
                                    case R.id.editmenu:
                                        if(position1 != RecyclerView.NO_POSITION && listener1 != null) 
                                            listener1.onItemclick1(notes.get(position1));
                                        
                                        break;
                                    case R.id.deletemenu:
                                        if(position1 != RecyclerView.NO_POSITION && listener != null) 
                                            listener.onItemclick(notes.get(position1));
                                        
                                        break;
                                    case R.id.sharenote:
                                        if(position1 != RecyclerView.NO_POSITION && listener3 != null) 
                                            listener3.onItemclick3(notes.get(position1));
                                        
                                
                                return true;
                            
                        );
                    
                );
    
            
        
        public interface onItemClicklistener
            void onItemclick(Note note);
        
        public void setonItemClicklistener(onItemClicklistener listener)
            this.listener = listener;
    
        
        public interface onItemClicklistener1
            void onItemclick1(Note note);
        
        public void setonItemClicklistener1(onItemClicklistener1 listener1)
            this.listener1 = listener1;
    
        
        public interface onItemClicklistener2
            void onItemclick2(Note note);
        
        public void setonItemClicklistener2(onItemClicklistener2 listener2)
            this.listener2 =  listener2;
        
        public interface onItemClicklistener3
            void onItemclick3(Note note);
        
        public void setonItemClicklistener3(onItemClicklistener3 listener3)
            this.listener3 = listener3;
        
    




**My add note activity**

package com.cksapp.mvvmarchitecture;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.util.Log;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.NumberPicker;
import android.widget.Toast;

import java.text.DateFormat;
import java.util.Calendar;
import java.util.Date;

public class NewActivityNote extends AppCompatActivity 
    EditText title, description;

    public static final String EXTRA_TITLE = "com.cksapp.mvvmarchitecture.EXTRA_TITLE";
    public static final String EXTRA_ID = "com.cksapp.mvvmarchitecture.EXTRA_ID";
    public static final String EXTRA_DESCRIPTION = "com.cksapp.mvvmarchitecture.EXTRA_DESCRIPTION";
    String currentDate;


    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_new_note);
        title = findViewById(R.id.title1);
        description = findViewById(R.id.description1);
        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_close);

        Intent intent = getIntent();
        if(intent.hasExtra(EXTRA_ID))
            setTitle("Edit Note");
            title.setText(intent.getStringExtra(EXTRA_TITLE));
            description.setText(intent.getStringExtra(EXTRA_DESCRIPTION));
        

        setTitle("Add Note");
    

    @Override
    public boolean onCreateOptionsMenu(Menu menu) 
        MenuInflater menuInflater = getMenuInflater();
        menuInflater.inflate(R.menu.new_note, menu);
        return true;
    

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) 
        switch (item.getItemId())
            case R.id.save:
                savenote();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        
       
    

    private void savenote() 
        String title1 = title.getText().toString();
        String description1 = description.getText().toString();


        if(title1.trim().isEmpty() || description1.trim().isEmpty())
            Toast.makeText(NewActivityNote.this, "Enter title and description",Toast.LENGTH_SHORT).show();
            return;
        

        Intent data = new Intent();
        data.putExtra(EXTRA_TITLE, title1);
        data.putExtra(EXTRA_DESCRIPTION, description1);


        int id = getIntent().getIntExtra(EXTRA_ID, -1);
        if(id != -1)
            data.putExtra(EXTRA_ID, id);
        


        setResult(RESULT_OK, data);
        finish();
    

    public void doSave(View view) 
        savenote();
    

正如你所建议的，我在项目中的更改是，这是我添加的转换器类

    import androidx.room.TypeConverter;

import java.sql.Date;


public class Converters 
    @TypeConverter
    public static Date fromTimestamp(Long value) 
        return value == null ? null : new Date(value);
    

    @TypeConverter
    public static Long dateToTimestamp(Date date) 
        return date == null ? null : date.getTime();
    

我在实体类中添加了日期对象

import androidx.room.Entity;
import androidx.room.PrimaryKey;

import java.sql.Date;


@Entity(tableName = "note_table")
public class Note 
    @PrimaryKey(autoGenerate = true)
    private int id;
    private String title;
    private String description;
    private Date date;



    public Note(String title, String description) 
        this.title = title;
        this.description = description;

    
   public void setDate(Date date)
        this.date = date;
   

   public Date getDate()
        return date;
   

    public void setId(int id) 
        this.id = id;
    

    public int getId() 
        return id;
    

    public String getTitle() 
        return title;
    


    public String getDescription() 
        return description;
    

下面是我要记录日期的NewNoteActivity保存笔记方法

private void savenote() 
        String title1 = title.getText().toString();
        String description1 = description.getText().toString();
        Date date = Calendar.getInstance().getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
        currentDate = sdf.format(date);

接下来我尝试将 currentDate 字符串访问到我的适配器类中以设置日期

 @Override
    public void onBindViewHolder(@NonNull NoteHolder holder, final int position) 
        final Note currentNote = notes.get(position);
        holder.textViewTitle.setText(currentNote.getTitle());
        holder.textViewDescription.setText(currentNote.getDescription());
        NewActivityNote n = new NewActivityNote();
        String date = n.currentDate;
        holder.textViewdate.setText(date);

最后它给了我 null 代替日期文本视图。文本视图最终设置为空（空）

执行上述任务后我的模拟器的屏幕截图 result

下面是我完整的NewNoteActivity

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.util.Log;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.NumberPicker;
import android.widget.TextView;
import android.widget.Toast;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

public class NewActivityNote extends AppCompatActivity 
    EditText title, description;

    public static final String EXTRA_TITLE = "com.cksapp.mvvmarchitecture.EXTRA_TITLE";
    public static final String EXTRA_ID = "com.cksapp.mvvmarchitecture.EXTRA_ID";
    public static final String EXTRA_DESCRIPTION = "com.cksapp.mvvmarchitecture.EXTRA_DESCRIPTION";
    String currentDate;


    @Override
    protected void onCreate(Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_new_note);
        title = findViewById(R.id.title1);
        description = findViewById(R.id.description1);
        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_close);

        Intent intent = getIntent();
        if(intent.hasExtra(EXTRA_ID))
            setTitle("Edit Note");
            title.setText(intent.getStringExtra(EXTRA_TITLE));
            description.setText(intent.getStringExtra(EXTRA_DESCRIPTION));
        

        setTitle("Add Note");
    

    @Override
    public boolean onCreateOptionsMenu(Menu menu) 
        MenuInflater menuInflater = getMenuInflater();
        menuInflater.inflate(R.menu.new_note, menu);
        return true;
    

    @Override
    public boolean onOptionsItemSelected(@NonNull MenuItem item) 
        switch (item.getItemId())
            case R.id.save:
                savenote();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        
       
    

    private void savenote() 
        String title1 = title.getText().toString();
        String description1 = description.getText().toString();
        Date date = Calendar.getInstance().getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-mm-dd hh:mm:ss");
        currentDate = sdf.format(date);



        if(title1.trim().isEmpty() || description1.trim().isEmpty())
            LayoutInflater inflater = getLayoutInflater();
            View layout = inflater.inflate(R.layout.toast_custom, (ViewGroup) findViewById(R.id.toastlayout));
            TextView t1 = layout.findViewById(R.id.toasttext);
            ImageView i1 = layout.findViewById(R.id.toastimage);
            t1.setText("Enter title and description");
            i1.setImageResource(R.drawable.ic_error);
            Toast toast = new Toast(getApplicationContext());
            toast.setGravity(Gravity.CENTER, 0, 0);
            toast.setDuration(Toast.LENGTH_LONG);
            toast.setView(layout);
            toast.show();
            return;
        

        Intent data = new Intent();
        data.putExtra(EXTRA_TITLE, title1);
        data.putExtra(EXTRA_DESCRIPTION, description1);


        int id = getIntent().getIntExtra(EXTRA_ID, -1);
        if(id != -1)
            data.putExtra(EXTRA_ID, id);
        
        LayoutInflater inflater = getLayoutInflater();
        View layout = inflater.inflate(R.layout.toast_custom, (ViewGroup) findViewById(R.id.toastlayout));
        TextView t1 = layout.findViewById(R.id.toasttext);
        ImageView i1 = layout.findViewById(R.id.toastimage);
        t1.setText("Enjoy, Note saved to your collections!");
        i1.setImageResource(R.drawable.ic_check);
        Toast toast = new Toast(getApplicationContext());
        toast.setGravity(Gravity.CENTER, 0, 0);
        toast.setDuration(Toast.LENGTH_LONG);
        toast.setView(layout);
        toast.show();


        setResult(RESULT_OK, data);
        finish();
    

    public void doSave(View view) 
        savenote();
    

我的道课

package com.cksapp.mvvmarchitecture;

import androidx.lifecycle.LiveData;

import androidx.room.Dao;
import androidx.room.Delete;
import androidx.room.Insert;
import androidx.room.Query;

import androidx.room.Update;

import java.util.List;

@Dao
public interface NoteDao 

    @Insert
    void insert(Note note);

    @Update
    void update(Note note);

    @Delete
    void delete(Note note);

    @Query("DELETE FROM note_table")
    void deleteAllNotes();



    @Query("Select * from note_table order by id desc")
    LiveData<List<Note>> getAllNotes();

【问题讨论】：

使用您当前的实现，它们都将显示相同的时间，因为您正在制作日历的实例，因为它们是绑定的，您没有从实际个人@987654330 那里获得时间@对象

我试图通过实例化日历类从 NewActivityNote 中提取时间，但我得到的是空值，而不是所需的日期。谢谢

【参考方案1】：

如前所述，您需要将日期保存在便笺实体中。

如果您对获得时间的推荐方式感兴趣，请阅读this answer。

然后，您应该将您的时间转换为 Long 并将其（在您的 note 类中）保存到数据库中。 然后在显示日期时，您必须将数字转换回格式化的日期。

也可以让Room 处理带有时间信息的复杂对象，例如Date 类（由c.getTime() 调用返回）。 作为将Date 对象保存到数据库的示例，您可以定义一个简单的转换器类，如文档中的this example。

【讨论】：

感谢@cewaphi 我是否还必须在笔记实体的构造函数中保存日期对象？谢谢！

“在构造函数中保存日期对象”是指类的构造函数将Date 类型变量作为输入参数，因此您的实体具有Date 类型的成员变量？如果你想把它保存到你的 Room 数据库中，你需要创建一个如上所述的转换器类。否则，Room 只能处理原始类型，例如String 和Boolean

请检查我的更改@cewaphi 感谢您的时间！

请问您为什么要尝试为日期创建活动实例而不是从您的currentNote 访问日期？你的savenote 方法在那里完成了吗？我没有看到任何保存操作发生

我这样做是因为我想保存用户单击保存按钮的日期。这是新笔记活动中的一种方法。我认为如果我添加全新的笔记活动类就很清楚了。 @cewaphi