java - 找不到符号 setonClickListener

Question

我正在尝试在 Android 应用程序中为 recycleview 设置 onlclick 监听器，但尽管一切都正确，但我仍然在 IDE 中收到上述错误。

这是 DrinksActivity 类的完整代码，显示了我如何尝试添加 clickListener

    public class DrinksActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener, OnItemClickListener {
//recyclerview object
private RecyclerView recyclerView;

//adapter object
private RecyclerView.Adapter adapter;
private ItemsAdapter itemsAdapter;

//database reference
private DatabaseReference mDatabase;

//progress dialog
private ProgressDialog progressDialog;

//list to hold all the uploaded images
private List<Upload> uploads;
TableLayout item;
Menu menu;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_drinks);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
    recyclerView = findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    item = findViewById(R.id.item);

    progressDialog = new ProgressDialog(this);

    uploads = new ArrayList<>();

    //displaying progress dialog while fetching images
    progressDialog.setMessage("Loading Items Please wait...");
    progressDialog.show();
    mDatabase = FirebaseDatabase.getInstance().getReference(Constants.DATABASE_PATH_UPLOADS);
    Query query = mDatabase.orderByChild("category").equalTo("Ecohim");


    //adding an event listener to fetch values
    query.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot snapshot) {
            //dismissing the progress dialog
            progressDialog.dismiss();

            //iterating through all the values in database
            for (DataSnapshot postSnapshot : snapshot.getChildren()) {
                Upload upload = postSnapshot.getValue(Upload.class);
                uploads.add(upload);
            }
            //creating adapter
            adapter = new ItemsAdapter(getApplicationContext(), uploads);

            //adding adapter to recyclerview
            recyclerView.setAdapter(adapter);
            adapter.setClickListener(ItemsAdapter.class);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            progressDialog.dismiss();
        }
    });
}

@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    MenuItem itemCart = menu.findItem(R.id.action_settings);
    LayerDrawable icon = (LayerDrawable) itemCart.getIcon();
    setBadgeCount(this, icon, "9");
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }
    else if(id == R.id.action_check_out){

    }
    else if(id == R.id.action_clear_cart){
        MenuItem itemCart = menu.findItem(R.id.action_settings);
        LayerDrawable icon = (LayerDrawable) itemCart.getIcon();
        setBadgeCount(this, icon, "9");

    }
    else{
        startActivity(new Intent(this, LoginActivity.class));
        finish();
    }

    return super.onOptionsItemSelected(item);
}
@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();
    if (id == R.id.nav_manage) {
    } else if (id == R.id.nav_drinks) {
        startActivity(new Intent(this, DrinksActivity.class));
    } else if (id == R.id.nav_seeds) {
        startActivity(new Intent(this, DrinksActivity.class));
    }
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
public static void setBadgeCount(Context context, LayerDrawable icon, String count) {

    BadgeDrawable badge;

    // Reuse drawable if possible
    Drawable reuse = icon.findDrawableByLayerId(R.id.ic_badge);
    if (reuse != null && reuse instanceof BadgeDrawable) {
        badge = (BadgeDrawable) reuse;
    } else {
        badge = new BadgeDrawable(context);
    }

    badge.setCount(count);
    icon.mutate();
    icon.setDrawableByLayerId(R.id.ic_badge, badge);
}

@Override
public void onClick(View view, int position) {
    Toast.makeText(getApplicationContext(), "Enter Your Email",Toast.LENGTH_SHORT).show();
}
}

这里是 ItemsAdapter 类文件，其中找到了 setClickListener 方法

    public class ItemsAdapter extends RecyclerView.Adapter<ItemsAdapter.ViewHolder> {
private Context context;
private List<Upload> uploads;
private OnItemClickListener clickListener;

public ItemsAdapter(Context context, List<Upload> uploads) {
    this.uploads = uploads;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_items, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);

            return  viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Upload upload = uploads.get(position);
    holder.textViewName.setText(upload.getName());
    holder.textdescription.setText(upload.getDescription());
    holder.textcost.setText( "Ksh" + upload.getCost());
    Glide.with(context).load(upload.getUrl()).into(holder.imageView);

}

@Override
public int getItemCount() {
    return uploads.size();
}
public void setClickListener(OnItemClickListener itemClickListener) {
    this.clickListener = itemClickListener;
}
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    public TextView textViewName, textdescription, textcost;
    public ImageView imageView;
    public ViewHolder(View itemView) {
        super(itemView);
        textViewName = itemView.findViewById(R.id.textViewName);
        textdescription = itemView.findViewById(R.id.textdescription);
        textcost = itemView.findViewById(R.id.textcost);
        imageView = itemView.findViewById(R.id.imageView);
        itemView.setOnClickListener(this); // bind the listener
    }

    @Override
    public void onClick(View v) {
        clickListener.onClick(v, getPosition()); // call the onClick in the OnItemClickListener
    }
}
}

最后这是 OnItemClickListener 接口(interface)代码

    public interface OnItemClickListener {
void onClick(View view, int position);}

我删除了所有导入和包声明行以使代码更短。我可能做错了什么以及如何解决它？谢谢

Answer 1

您已经非常接近解决问题了。你在 Activity 方面做得很好。而且你的思维方式是正确的。

问题在于您将 onItemClickedListener 转换为 OnClickListener 的方式。

首先，您应该重命名(通过重构)您的自定义 ViewHolder，因为它可能会导致困惑。 (可选)

public class ViewHolder extends RecyclerView.ViewHolder

重命名为:

public class CustomViewHolder extends RecyclerView.ViewHolder

接下来，不要直接实现 onClickListener，只需一个 setter 即可:

public class CustomViewHolder extends RecyclerView.ViewHolder {

public TextView textViewName, textdescription, textcost;
public ImageView imageView;

//save itemview
private View itemView;

public void ViewHolder(View itemView) {
    super(itemView);
    textViewName = itemView.findViewById(R.id.textViewName);
    textdescription = itemView.findViewById(R.id.textdescription);
    textcost = itemView.findViewById(R.id.textcost);

    //assign itemView
    this.itemView = itemView;
    imageView = itemView.findViewById(R.id.imageView);
    //don't set listener here
}

//create a setter method 
public setHolderClickListener(View.OnClickListener listener){
      itemView.setOnClickListener(listener);

}

}

最后，我们将使用一个简单的闭包将位置转移到 onItemClickListener:

public class ItemsAdapter extends RecyclerView.Adapter<ItemsAdapter.CustomViewHolder> {
...
@Override
//I used renamed ViewHolder
public void onBindViewHolder(CustomViewHolder holder, int position) {
    Upload upload = uploads.get(position);
    holder.textViewName.setText(upload.getName());
    holder.textdescription.setText(upload.getDescription());
    holder.textcost.setText( "Ksh" + upload.getCost());
    Glide.with(context).load(upload.getUrl()).into(holder.imageView);

    //assign listener here:
    holder.setHolderClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
             //this is the place where you should call this and everything works ;) 
             clickListener.onClick(v,position);
        }
    };

}

}

最终的适配器类:

public class ItemsAdapter extends RecyclerView.Adapter<ItemsAdapter.CustomViewHolder> {
private Context context;
private List<Upload> uploads;
private OnItemClickListener clickListener;

public ItemsAdapter(Context context, List<Upload> uploads) {
    this.uploads = uploads;
    this.context = context;
}

@Override
public ViewHolder onCreateViewHolder(final ViewGroup parent, final int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_items, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return  viewHolder;
}

@Override
public void onBindViewHolder(CustomViewHolder holder, int position) {
    Upload upload = uploads.get(position);
    holder.textViewName.setText(upload.getName());
    holder.textdescription.setText(upload.getDescription());
    holder.textcost.setText( "Ksh" + upload.getCost());
    Glide.with(context).load(upload.getUrl()).into(holder.imageView);

    //assign listener here:
    holder.setHolderClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //this is the place where you should call this and everything works ;)
            clickListener.onClick(v,position);
        }
    };

}

@Override
public int getItemCount() {
    return uploads.size();
}
public void setClickListener(OnItemClickListener itemClickListener) {
    this.clickListener = itemClickListener;
}


public class CustomViewHolder extends RecyclerView.ViewHolder{

    public TextView textViewName, textdescription, textcost;
    public ImageView imageView;

    //save itemview
    private View itemView;

    public void CustomViewHolder(View itemView) {
        super(itemView);
        textViewName = itemView.findViewById(R.id.textViewName);
        textdescription = itemView.findViewById(R.id.textdescription);
        textcost = itemView.findViewById(R.id.textcost);

        //assign itemView
        this.itemView = itemView;
        imageView = itemView.findViewById(R.id.imageView);
        //don't set listener here
       }

    //create a setter method
    public void setHolderClickListener(View.OnClickListener listener){
        itemView.setOnClickListener(listener);

    }
  }
}

重要:确保导入您的 OnItemClickListener

NB:这只是解决问题的一种方法。您还可以使用 lambda 表达式、自定义接口(interface)、事件总线或 react 流。希望对你有帮助:D