仅显示一项的列表视图

Posted 2023-04-19

【中文标题】仅显示一项的列表视图

【英文标题】：List view only showing one item

【发布时间】：2018-04-22 00:54:45

【问题描述】：

我正在制作 android ListView 以显示 Firebase 数据库中的对象，但我正在添加项目，但 ListView 中仅显示一项。我正在使用ArrayAdapter，所有代码都在下面。仅显示第一项，而不是提供的所有数据

示例 JSON 文件在这里：

  "items" : 
    "item0" : 
      "description" : "its an apple",
      "name" : "apples",
      "price" : 10,
      "productID" : 0,
      "quantity" : 5,
      "type" : "fruit"
    ,
    "item1" :  
      "description" : "its an orange",
      "name" : "oranges",
      "price" : 10,
      "productID" : 1,
      "quantity" : 15,
      "type" : "fruit"
      ,
      "item2" :  
      "description" : "bagle",
      "name" : "bagles",
      "price" : 9,
      "productID" : 2,
      "quantity" : 7,
      "type" : "food"
      
  ,

  "users" : 
    "dummy" : "keep this entry. without this, the other entries won't appear on the database"
  

http://paste.ubuntu.com/25916653/

activity_main_app_page.xml

<android.support.design.widget.CoordinatorLayout    
    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:id="@+id/main_content"
    android:layout_
    android:layout_
    android:fitsSystemWindows="true"
    tools:context="com.ub.akshay.nitkart.MainAppPage">

    <android.support.design.widget.AppBarLayout
        android:id="@+id/appbar"
        android:layout_
        android:layout_
        android:paddingTop="@dimen/appbar_padding_top"
        android:theme="@style/AppTheme.AppBarOverlay">

        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_
            android:layout_
            android:background="?attr/colorPrimary"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/AppTheme.PopupOverlay">

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

    </android.support.design.widget.AppBarLayout>

    <ListView
        android:id="@+id/shoppingList"
        android:orientation="vertical"
        android:layout_
        android:layout_
        android:paddingTop="8dp"
        android:paddingBottom="120dp"
        android:clipToPadding="false"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        android:scrollbarStyle="outsideOverlay" />

    <ProgressBar
        android:id="@+id/mainPageProgressBar"
        android:layout_
        android:layout_
        android:layout_gravity="center" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/cartMainPage"
        android:layout_
        android:layout_
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"
        app:backgroundTint="@android:color/background_light"
        app:srcCompat="@drawable/ic_shopping_cart_black_24dp" />


</android.support.design.widget.CoordinatorLayout>`

MainActivity.java

package com.ub.tom.smith;

import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ListView;
import android.widget.ProgressBar;

import com.google.firebase.auth.FirebaseAuth;
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;

public class MainAppPage extends AppCompatActivity 

    public final String TAG = MainAppPage.class.getSimpleName();
    ListView shoppingItemView;
    ShoppingListAdapter adapter;
    ProgressBar progressBar;
    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference("items");
    private Boolean exit = false;
    private ArrayList<ShoppingItem> shoppingItems;

    @Override
    protected void onCreate(Bundle savedInstanceState) 

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_app_page);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        toolbar.setTitle("NITKart");
        setSupportActionBar(toolbar);

        FloatingActionButton shoppingCart = (FloatingActionButton)    
        findViewById(R.id.cartMainPage);
        shoppingCart.setOnClickListener(new View.OnClickListener() 
            @Override
            public void onClick(View view) 
                startActivity(new Intent(getApplicationContext(),   
                ShoppingCartWindow.class));
            
        );

        progressBar = (ProgressBar)   
        findViewById(R.id.mainPageProgressBar);
        shoppingItemView = (ListView) findViewById(R.id.shoppingList);

        myRef.addValueEventListener(new ValueEventListener() 
            // This listener is only for database with reference of key 
            "items"
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) 
                // This method is called once with the initial value and           
                 again
                // whenever data at this location is updated.

                // Now the Shopping List gets updated whenever the data 
                shoppingItems = getAllItems(dataSnapshot);
                adapter = new ShoppingListAdapter(getApplicationContext(), 
                shoppingItems);
                progressBar.setVisibility(View.GONE);
                shoppingItemView.setAdapter(adapter);
            

            @Override
            public void onCancelled(DatabaseError error) 
                // Failed to read value
                Log.w(TAG, "Failed to read value.", error.toException());
            
        );

        shoppingItemView.setOnItemClickListener(new  
        AdapterView.OnItemClickListener() 
            @Override
            public void onItemClick(AdapterView<?> adapterView, View view,  
            int i, long l) 
                Intent productIntent = new Intent(MainAppPage.this,  
                IndividualProduct.class);
                productIntent.putExtra("product", shoppingItems.get(i));
                startActivity(productIntent);
            
        );

    


    @Override
    public boolean onCreateOptionsMenu(Menu menu) 
        // Inflate the menu; this adds items to the action bar if it is 
        getMenuInflater().inflate(R.menu.menu_main_app_page, menu);
        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.logoutItem) 
            FirebaseAuth.getInstance().signOut();
            startActivity(new Intent(getApplicationContext(), 
            OpenScreen.class));
            finish();
        

        return super.onOptionsItemSelected(item);
    

    // For exiting the application
    @Override
    public void onBackPressed() 
        if (exit) 
            finish();
         else 
            Snackbar.make(findViewById(R.id.main_content), "Press back  
            again to exit", Snackbar.LENGTH_SHORT).show();
            exit = true;
            new Handler().postDelayed(new Runnable() 
                @Override
                public void run() 
                    exit = false;
                
            , 2000);
        
    

    public static ArrayList<ShoppingItem> getAllItems(DataSnapshot 
     dataSnapshot)

        ArrayList<ShoppingItem> items  = new ArrayList<ShoppingItem>();

        for (DataSnapshot item : dataSnapshot.getChildren()) 

            items.add(new ShoppingItem(

           Integer.valueOf(item.child("productID").getValue().toString()),
                    item.child("name").getValue().toString(),
                    item.child("type").getValue().toString(),
                    item.child("description").getValue().toString(),

           Integer.valueOf(item.child("price").getValue().toString()),

           Integer.valueOf(item.child("quantity").getValue().toString())
            ));

        

        return items;
    

【问题讨论】：

请把你的代码不要链接。

@DRPK 我刚刚包含了代码

你在哪里设置 ArrayAdapter？

我建议您在数据库中使用 Java objects to read and write 您的 ShoppingItem 实例。然后您可以使用FirebaseUI Database library 来简化将数据绑定到ListView。

【参考方案1】：

你能检查 ShoppingListAdapter setSize() 是否与 shoppingItems 列表大小相同

【讨论】：

能否请您详细说明代码中没有 setSize() 属性

在 ShoppingListAdapter 中存在覆盖方法 setSize()，检查其值

【参考方案2】：

在您的onDataChange() 方法中尝试添加runOnUiThread。并且在新的 Runnable 中包含适配器代码。

【讨论】：

在调用线程上调用了onDataChange()方法，所以不需要runOnUiThread。