android - 自定义ListView不显示

Question

有人能告诉我我在制作自定义 ListView 时犯了什么错误吗，因为它在使用自定义适配器时不显示任何数据。虽然它在一个简单的数组适配器上工作，但我不明白我定制的适配器是否有错误？？

这是我的主要 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=".SubCategories"
    android:weightSum="10">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_weight="1">
        <TextView
            android:gravity="center"
            android:id="@+id/suitablecategory"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Add Services"
            android:textStyle="bold"
            android:textAppearance="@android:style/TextAppearance.Large" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_weight="1">
        <Spinner
            android:id="@+id/Spin"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:orientation="vertical"
        android:gravity="center"
        android:layout_weight="8">
        <ListView
            android:id="@+id/SubListView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content">
        </ListView>
    </LinearLayout>
</LinearLayout>

这是我的行项目 Xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:weightSum="2">
    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">
        <TextView
            android:id="@+id/CustomListItemName"
            android:layout_gravity="center"
            android:hint="Name"
            android:textStyle="bold"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textAppearance="@android:style/TextAppearance.Medium"/>
    </LinearLayout>

    <LinearLayout
        android:layout_width="0dp"
        android:layout_height="match_parent"
        android:layout_weight="1"
        android:orientation="vertical">
        <EditText
            android:hint="Enter Price"
            android:layout_gravity="center"
            android:id="@+id/CustomListItemPrice"
            android:inputType="number"
            android:textStyle="bold"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </LinearLayout>
</LinearLayout>

这是我定制的适配器

package application.fyp.com.myfypapplication;

import android.app.Activity;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.EditText;
import android.widget.TextView;

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

public class PriceListAdapter extends ArrayAdapter<String> {

    private Context context;
    private List<String> items;

    public PriceListAdapter(Context context, List<String> list) {
        super(context, R.layout.custom_price_listview,R.id.CustomListItemName,list);
        this.context = context;
        this.items = list;
    }


    @Override
    public int getCount() {
        return 0;
    }

    @Nullable
    @Override
    public String getItem(int position) {
        return super.getItem(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @NonNull
    @Override
    public View getView(int position, @Nullable View convertView, @NonNull ViewGroup parent) {
        LayoutInflater layoutInflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        convertView = layoutInflater.inflate(R.layout.custom_price_listview, parent,false);
        TextView  name = convertView.findViewById(R.id.CustomListItemName);
        EditText price = convertView.findViewById(R.id.CustomListItemPrice);
        String it = items.get(position);
        name.setText(it);
        return convertView;
    }

}

这是我的主类，我在其中使用适配器初始化和设置 ListView

package application.fyp.com.myfypapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Spinner;
import android.widget.Toast;

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

public class SubCategories extends AppCompatActivity {

    private Spinner spinner;
    private ListView lv;
    private Button addsc;
    private PriceListAdapter priceadapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sub_categories);

        spinner=(Spinner)findViewById(R.id.Spin);
        lv = findViewById(R.id.SubListView);

        List<String> subCategoryList = new ArrayList<>();
        subCategoryList.add("A");
        subCategoryList.add("B");
        subCategoryList.add("C");
        subCategoryList.add("D");
        priceadapter = new PriceListAdapter(SubCategories.this, subCategoryList);
        lv.setAdapter(priceadapter);



    }

Answer 1

在您的适配器中，您必须更改以下内容:

@Override
public int getCount() {
    // return 0; // This is what you have now
    return this.items.size(); // This is what it must be
}

getCount 方法旨在返回 ListView 中的项目数。