使用未在回收站视图中显示的毕加索图像

Question

我正在尝试在 android studio 的回收器视图中显示 Firebase 数据库中的图像，但图像未显示。我不确定我哪里出了问题或问题出在哪里。

主Activity.xml

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout 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"
        android:orientation="vertical"
        tools:context="com.test.test.AddBrandPage"
        android:weightSum="1">


    <TextView
        android:id="@+id/editText"
        android:layout_width="383dp"
        android:layout_height="wrap_content"
        android:layout_alignParentEnd="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        android:layout_marginTop="17dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="Select your favourite stores..."
        android:textAlignment="center"
        android:textSize="22sp" />

    <LinearLayout
        android:id="@+id/alphaindex"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:orientation="horizontal"></LinearLayout>


    <android.support.v7.widget.RecyclerView
        android:id="@+id/recylView"
        android:layout_width="337dp"
        android:layout_height="370dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_below="@+id/editText2"
        android:layout_marginLeft="14dp"
        android:layout_marginRight="14dp"
        android:layout_marginStart="14dp"
        android:layout_marginTop="24dp"
        android:layout_weight="0.23"
        android:scrollbars="vertical">              
        </android.support.v7.widget.RecyclerView>


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.11"
        android:layout_marginTop="20dp"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_skip"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="25dp"
            android:layout_marginTop="15dp"
            android:layout_marginRight="15dp"
            android:background="@color/colorPrimary"
            android:text="Skip"
            android:textAllCaps="true"
            android:textColor="@android:color/background_light"
            android:textSize="20sp"
            android:textStyle="normal|bold" />

        <Button
            android:id="@+id/btn_submit"
            android:layout_width="150dp"
            android:layout_height="wrap_content"
            android:layout_marginLeft="15dp"
            android:layout_marginTop="15dp"
            android:layout_marginRight="20dp"
            android:background="@color/colorPrimary"
            android:text="Submit"
            android:textAllCaps="true"
            android:textColor="@android:color/background_light"
            android:textSize="20sp"
            android:textStyle="normal|bold" />

      </LinearLayout>

    </LinearLayout>

Logo_items.xml

      <?xml version="1.0" encoding="utf-8"?>
      <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          xmlns:cardView="http://schemas.android.com/apk/res-auto"
          android:id="@+id/logo_container"
          android:layout_width="match_parent"
          android:layout_height="100dp"
          android:background="@android:color/darker_gray"
          android:gravity="center_vertical|center_horizontal"
          android:orientation="vertical"
          android:paddingBottom="10dp"
          android:paddingLeft="10dp"
          android:paddingRight="10dp"
          android:paddingTop="10dp"
          android:visibility="visible"
          cardView:layout_collapseParallaxMultiplier="1.0">

    <android.support.v7.widget.CardView
        android:layout_width="155dp"
        android:layout_height="100dp"
        android:layout_marginBottom="5dp"
        android:layout_marginTop="5dp"
        cardView:cardBackgroundColor="@android:color/white">


        <GridLayout
            android:id="@+id/cardView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_gravity="center_horizontal|center_vertical"
            android:orientation="vertical">


            <ImageView
                android:id="@+id/img_logo"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_column="1"
                android:layout_gravity="center_horizontal|center_vertical"
                android:layout_row="0"
                android:paddingBottom="5dp"
                android:paddingLeft="2.5dp"
                android:paddingRight="2.5dp"
                android:paddingTop="5dp">

            </ImageView>

        </GridLayout>

        <CheckBox
            android:id="@+id/checkbox"
            android:layout_width="30dp"
            android:layout_height="30dp"
            android:layout_marginLeft="130dp"
            android:layout_marginTop="66dp"
             />

    </android.support.v7.widget.CardView>

    </LinearLayout>

LogoItems.java

    public class LogoItems {

        //declare variables(the items displayed in the layout)
        private String logo;//, name;

        public String getLogo() {
            return logo;
        }

        public void setLogo(String logo) {
            this.logo = logo;
        }

     }

主Activity.java

package com.test.test;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

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.util.ArrayList;
import java.util.HashMap;
import java.util.List;

public class AddBrandPage extends AppCompatActivity implements OnClickListener {

    //declare variables
    private RecyclerView recyclerView;
    private RecyclerView.LayoutManager layoutManager;
    private RecyclerView.Adapter adapter;
    private DatabaseReference myRef;
    private Button btn_skip;
    private Button btn_submit;
    //private String name;
    //private String url;

    List<LogoItems> brandLogo = new ArrayList<>();
    //HashMap<String, String> dataSet = new HashMap<>();



    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_brand_page);

        //initialize variables
        btn_skip = (Button) findViewById(R.id.btn_skip);
        btn_submit = (Button) findViewById(R.id.btn_submit);
        myRef = FirebaseDatabase.getInstance().getReference().child("/brands");

        // set the main recyclerview view in the layout
        recyclerView = (RecyclerView) findViewById(R.id.recylView);
        recyclerView.setHasFixedSize(true);

        // set the main layoutManager of the recyclerview
        layoutManager = new GridLayoutManager(this, 2);
        recyclerView.setLayoutManager(layoutManager);


        loadLogoImgData();


        // set the recycler view adapter
        adapter =  new LogoAdapter(brandLogo, getBaseContext());
        recyclerView.setAdapter(adapter);

        //set the listener for the buttons click event
        btn_skip.setOnClickListener(this);
        btn_submit.setOnClickListener(this);


    }

    @Override
    public void onClick(View view) {

        if (view == btn_skip) {
            //if skip button clicked close current window and go to user main page
            finish();
            startActivity(new Intent(getApplicationContext(), UserMainPage.class));

        }

    }



    public void loadLogoImgData(){

        brandLogo.clear();
        myRef.addValueEventListener(new ValueEventListener() {

            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                for (DataSnapshot brandSnapshot : dataSnapshot.getChildren()){
                    LogoItems value = brandSnapshot.getValue(LogoItems.class);
                    LogoItems brandDetails = new LogoItems();
                   // String name = value.getName();
                    String logos = value.getLogo();
                    //brandDetails.setName(name);
                    brandDetails.setLogo(logos);
                    brandLogo.add(brandDetails);

            }
        }


            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

      }
    }

LogoItemsAdapter.java

package com.test.test;
import android.content.Context;
import android.net.Uri;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.ImageView;
import android.widget.Toast;

import com.squareup.picasso.Picasso;

import java.util.ArrayList;
import java.util.List;


public class LogoAdapter extends RecyclerView.Adapter<LogoAdapter.LogoViewHolder> {

    List<LogoItems> brandLogo = new ArrayList<>();
   // private AddBrandPage addBrandPage;
    private Context context;

    public LogoAdapter(List <LogoItems> brandLogo, Context context){
        this.brandLogo = brandLogo;
        this.context = context;
        //addBrandPage = (AddBrandPage)context;
    }


    @Override
    public LogoAdapter.LogoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.logo_items,parent,false);
        LogoViewHolder logoViewHolder = new LogoViewHolder(view);
        return logoViewHolder;
    }

    @Override
    public void onBindViewHolder(LogoAdapter.LogoViewHolder holder, int position) {

        //holder.logo.setImageURI(Uri.parse(brandLogo.get(position).getLogo()));
        Picasso.with(context).load(brandLogo.get(position).getLogo()).into(holder.logo);

    }

    @Override
    public int getItemCount() {

        return brandLogo.size();
    }



    public static class LogoViewHolder extends RecyclerView.ViewHolder{

        //declare variables
        public ImageView logo;
        CheckBox checkbox;
        //private View itemView;


        public LogoViewHolder(View itemView){
            super(itemView);

            //initialize variables inside the constructor
            logo = (ImageView)itemView.findViewById(R.id.img_logo);
            checkbox = (CheckBox)itemView.findViewById(R.id.checkbox);
           // this.itemView = itemView;

        }


    }


}

Answer 1

您的代码在这里看起来有点模糊：

myRef.addValueEventListener(new ValueEventListener() { 
@Override 
public void onDataChange(DataSnapshot dataSnapshot) { 
for (DataSnapshot brandSnapshot : dataSnapshot.getChildren()){    
LogoItems value =                
brandSnapshot.getValue(LogoItems.class); 
LogoItems brandDetails = 
 new LogoItems(); 
 // String name = value.getName(); 
 String logos = value.getLogo(); 
  //brandDetails.setName(name);
  brandDetails.setLogo(logos); 
  brandLogo.add(brandDetails); } }  

将此代码更改为：

 myRef.addValueEventListener(new ValueEventListener() { 
 @Override 
 public void onDataChange(DataSnapshot dataSnapshot) { 
 for (DataSnapshot brandSnapshot : dataSnapshot.getChildren()){    
 LogoItems value =                
 brandSnapshot.getValue(LogoItems.class);
 brandLogo.add(value); } 

  startRecyclerView();

  }  

Firebase 方法是异步的，您当前的代码会同步扩展 recylcerview，这意味着它会在设置和接收数据之前加载。

从数据库加载数据后，更改后的代码会异步启动 recyclerview。您可以添加进度条以了解状态。可以这样设置（在这个方法之前初始化，默认可见）：

  mProgressBar.setVisibility(View.INVISIBLE);
  startRecyclerView();

这样代码看起来井井有条。