我创建了一个数组列表,并将元素从从解析服务器接收到的值/对象推送到数组。现在主活动中的 listView 被重复值填充。列表项的数量(使用自定义适配器)等于数组长度。但是当我记录数组列表时,数组值中的值是唯一的并且不会重复。
package com.example.fooddeliveryapp;
import androidx.appcompat.app.AppCompatActivity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.provider.MediaStore;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import com.parse.FindCallback;
import com.parse.GetDataCallback;
import com.parse.ParseException;
import com.parse.ParseFile;
import com.parse.ParseObject;
import com.parse.ParseQuery;
import java.io.ByteArrayOutputStream;
import java.util.ArrayList;
import java.util.List;
public class ListFoods extends AppCompatActivity {
ListView listView;
ArrayList<Bitmap> images = new ArrayList<Bitmap>();
ArrayList<String> names = new ArrayList<String>();
ArrayList<String> restaurants = new ArrayList<String>();
//custom adapter
class custom extends BaseAdapter {
@Override
public int getCount() {
return names.size();
}
@Override
public Object getItem(int position) {
return null;
}
@Override
public long getItemId(int position) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = getLayoutInflater().inflate(R.layout.list_foods , null);
ImageView image = v.findViewById(R.id.foodImage);
TextView name = v.findViewById(R.id.foodName);
TextView restaurant = v.findViewById(R.id.restaurantName);
if(images.size() > 0){
image.setImageBitmap(images.get(position));
name.setText(names.get(position));
restaurant.setText(restaurants.get(position));
}
return v;
}
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list_foods);
getSupportActionBar().hide();
custom adapter = new custom();
//access views
listView = findViewById(R.id.listItems);
//get values from parse Server
ParseQuery query = ParseQuery.getQuery("Foods");
query.findInBackground(new FindCallback<ParseObject>() {
@Override
public void done(List<ParseObject> objects, ParseException e) {
for( ParseObject object : objects){
String name = object.getString("names");
String restaurant = object.getString("restaurants");
//add to array
names.add(name);
restaurants.add(restaurant);
//file
ParseFile file = object.getParseFile("image");
file.getDataInBackground(new GetDataCallback() {
@Override
public void done(byte[] data, ParseException e) {
if(e == null && data != null){
Bitmap bitmap = BitmapFactory.decodeByteArray(data , 0 , data.length);
images.add(bitmap);
}
}
});
}
Log.i("names" , names.toString());
listView.setAdapter(adapter);
}
});
}
}
请原谅我有史以来最糟糕的解释。这是输出屏幕截图 output
注意 - 列表项中的值是列表项中的默认值。这是列表项的xml代码
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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">
<ImageView
android:id="@+id/foodImage"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_marginStart="16dp"
android:layout_marginEnd="295dp"
android:scaleType="centerCrop"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:srcCompat="@drawable/melon"
tools:layout_editor_absoluteY="29dp" />
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="21dp"
android:layout_marginEnd="209dp"
android:fontFamily="sans-serif-thin"
android:text="Name: "
android:textSize="20sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toEndOf="@+id/foodImage"
tools:layout_editor_absoluteY="51dp" />
<TextView
android:id="@+id/foodName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="101dp"
android:text="WaterMelon"
android:textSize="20sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/name"
tools:layout_editor_absoluteY="51dp" />
<TextView
android:id="@+id/restaurant"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="22dp"
android:layout_marginTop="10dp"
android:text="Restaurant: "
android:textSize="20sp"
app:layout_constraintEnd_toStartOf="@+id/restaurantName"
app:layout_constraintStart_toEndOf="@+id/foodImage"
app:layout_constraintTop_toBottomOf="@+id/name" />
<TextView
android:id="@+id/restaurantName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:layout_marginEnd="59dp"
android:text="some hub"
android:textSize="20sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/restaurant"
app:layout_constraintTop_toBottomOf="@+id/foodName" />
</androidx.constraintlayout.widget.ConstraintLayout>