如何在 RecyclerView 中使 Material CardView 可检查

Question

我制作了一个 android 笔记应用程序，我想制作笔记 Material CardView，Checkable。我想要这种行为。当我长按每个笔记时，每个笔记都会 checked/selected（根据 material 设计卡片视图 setChecked 行为进行检查）。

它是一个带有 RecyclerView 和实现注释的 Room 持久性数据库。每个笔记布局都是一个 Material CardView。我有一个名为“NotesAdapter”的适配器、一个模型实体“Note”和名为“MyNotesActivity”的主要Activity。当然我还有一些文件，但我没有包含它们，因为我没有把整个项目都放在一起供你阅读。如果你想要他们，我会为你提出问题。

我已经试过了，但不能正常工作。在 NotesAdapter 中，行“noteHolder.noteCardView.toggle();”

noteHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    //When long clicking(holding click) on note(note title, note body text, note date).
                    listener.onNoteLongClick(note);

                    noteHolder.noteCardView.toggle();
                    return true;
                }
            });

当我长按时它确实被选中了，但是当我向下滚动时，其他一些笔记也会被选中。

例如

https://gfycat.com/incomparablepowerfullarva

我的“NotesAdapter.java”代码：

//implements Filterable is for some other feature, that has nothing to do with this question.
public class NotesAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements Filterable {

    public ArrayList<Note> notes;
    public ArrayList<Note> notesFull;
    private Context context;
    private NoteEventListener listener;
    private DeleteThisNoteListener deleteThisNoteListener;

    public NotesAdapter(ArrayList<Note> notes, Context context, DeleteThisNoteListener deleteThisNoteListener) {
        this.notes = notes;
        this.context = context;
        this.deleteThisNoteListener = deleteThisNoteListener;
        notesFull = new ArrayList<>(notes);
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View v = LayoutInflater.from(context).inflate(R.layout.note_layout, parent, false);
        return new NoteHolder(v);
    }

    //Displays data at specified position.
    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        final NoteHolder noteHolder = (NoteHolder) holder;
        final Note note = getNote(position);
        if (note != null) {
            //Entering text to each Text fields.
            noteHolder.noteTitle.setText(note.getNoteTitle());
            noteHolder.noteBodyText.setText(note.getNoteBodyText());
         noteHolder.noteDate.setText(NoteUtils.dateFromLong(note.getNoteDate()));

            noteHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    //When long clicking(holding click) on note(note title, note body text, note date).
                    listener.onNoteLongClick(note);

                    noteHolder.noteCardView.toggle();
                    return true;
                }
            });

            noteHolder.moreMenu.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    deleteThisNoteListener.onDeleteThisNoteClick(note, view, noteHolder.getBindingAdapterPosition());
                }
            });
        }
    }

    //Gets the particular note and its position.
    public Note getNote(int position) {
        return notes.get(position);
    }

    //Gets how many notes are there.
    @Override
    public int getItemCount() {
        return notes.size();
    }

    //setListener sets all listeners
    public void setListener(NoteEventListener listener, DeleteThisNoteListener deleteThisNoteListener) {
        this.listener = listener;
        this.deleteThisNoteListener = deleteThisNoteListener;
    }

    static class NoteHolder extends RecyclerView.ViewHolder {
        TextView noteTitle, noteBodyText, noteDate;
        MaterialButton moreMenu;
        MaterialCardView noteCardView;

        public NoteHolder(@NonNull View itemView) {
            super(itemView);
            noteCardView = itemView.findViewById(R.id.note);
            noteTitle = itemView.findViewById(R.id.note_title);
            noteBodyText = itemView.findViewById(R.id.note_body_text);
            noteDate = itemView.findViewById(R.id.note_date);
            moreMenu = itemView.findViewById(R.id.more_menu_button);
        }

    }

}

我的“MyNotesActivity.java”

public class MyNotesActivity extends AppCompatActivity implements NoteEventListener, DeleteThisNoteListener {

    private MaterialToolbar searchTopBar;
    private MaterialToolbar pageTitleTopBar;
    private MaterialToolbar selectNotesTopBar;
    private NotesDAO dao;
    private NotesAdapter adapter;
    private RecyclerView recyclerView;
    private LinearLayoutManager layoutManager;
    public static final String TAG = "MyNotie";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_my_notes);
        BottomAppBar bottomAppBar = findViewById(R.id.bottom_app_bar);
        setSupportActionBar(bottomAppBar);

        layoutManager = new LinearLayoutManager(this);
        recyclerView = findViewById(R.id.notes_list);
        recyclerView.setLayoutManager(layoutManager);
        dao = NotesDB.getInstance(this).notesDAO();

        FloatingActionButton add_new_note_button = findViewById(R.id.add_new_note);
        add_new_note_button.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                addNotes("This is a test note.", "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Proin et ante quis nibh blandit vehicula non sit amet dui.");
                addNotes("New note!", "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.");
                addNotes("Check this new note!", "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.");
                addNotes("Cool note!", "Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.");
                addNotes("Wrote it all down!", "Nullam imperdiet placerat porttitor. Ut ac urna sed magna gravida eleifend. ");
                loadNotes();
            }
        });

        recyclerView.addOnScrollListener(onScrollListener);
    }

    private void addNotes(String noteTitle, String noteBodyText) {
        for (int i=0; i<2; i++) {
            Note testNote = new Note();
            long date = new Date().getTime();
            testNote.setNoteTitle(noteTitle);
            testNote.setNoteBodyText(noteBodyText);
            testNote.setNoteDate(date);
            dao.insertNote(testNote);
            adapter.notesFull.add(testNote);
            adapter.notes.add(testNote);
        }
    }

    //When resuming the app while on sleep or opening the app this onResume 
    method is called.
    @Override
    protected void onResume() {
        super.onResume();
        loadNotes(); //loads/reloads notes from database.
    }

}

我的模型“Note.java”：

@Entity(tableName = "notes")
public class Note {
    @PrimaryKey(autoGenerate = true)
    private int id;
    @ColumnInfo(name = "isNewNote")
    private Boolean isNewNote = true;
    @ColumnInfo(name = "noteTitle")
    private String noteTitle;
    @ColumnInfo(name = "text")
    private String noteBodyText;
    @ColumnInfo(name = "date")
    private long noteDate;

    public Note() {
    }

    public String getNoteTitle() {
        return noteTitle;
    }

    public void setNoteTitle(String noteTitle) {
        this.noteTitle = noteTitle;
    }

    public String getNoteBodyText() {
        return noteBodyText;
    }

    public void setNoteBodyText(String noteBodyText) {
        this.noteBodyText = noteBodyText;
    }

    public long getNoteDate() {
        return noteDate;
    }

    public void setNoteDate(long noteDate) {
        this.noteDate = noteDate;
    }

    public int getId() {
        return id;
    }

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

    @NonNull
    public Boolean getIsNewNote() {
        return isNewNote;
    }

    public void setIsNewNote(@NonNull Boolean newNote) {
        isNewNote = newNote;
    }

    @NonNull
    @Override
    public String toString() {
        return "Note{" +
                "id=" + id +
                ", noteDate=" + noteDate +
                '}';
    }
}

请给我一些建议，因为我找不到任何有效的解决方案...在此先感谢您！

Answer 1

其实我明白了！我从这个人那里得到了这个想法：当他展示他的 RecyclerViewAdapter 和 Model 并在 RecyclerViewAdapter 中看到这个时：

holder.view.setBackgroundColor(model.isSelected() ? Color.CYAN : Color.WHITE);
        holder.textView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                model.setSelected(!model.isSelected());
                holder.view.setBackgroundColor(model.isSelected() ? Color.CYAN : Color.WHITE);
            }
        });

我做了这个： “NotesAdapter.java”

noteHolder.noteCardView.setChecked(note.isChecked());
            noteHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
                @Override
                public boolean onLongClick(View view) {
                    //When long clicking(holding click) on note(note title, note body text, 
                    note date).
                    note.setChecked(!note.isChecked());
                    noteHolder.noteCardView.setChecked(note.isChecked());

                    return true;
                }
            });

并在模型“Note.java”

中添加了 getter、“isChecked”和 setter“setChecked”

public class Note {
//The rest that are not mentioned, remain unchanged.
@Ignore
private boolean isChecked;

    public boolean isChecked() {
        return isChecked;
    }

    public void setChecked(boolean checked) {
        isChecked = checked;
    }
}

这就解决了！我希望这会帮助别人！它可能不是很好，但我希望它会有所帮助！感谢您看到这个 post！

如何在 RecyclerView 中使 Material CardView 可检查

How to make Material CardView, Checkable, in RecyclerView

android-studio

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materialcardview