我正在尝试创建一个包含列表的选项卡式活动。我已经创建了选项卡式活动，我想在片段中创建列表。每个列表项包含 2 个 ImageView 和 4 个 TextView。因此，我创建了一个自定义类和一个自定义 ArrayAdapter。这是代码 -
Coins.java - 这是选项卡式活动的片段。
package com.example.android.cotescol; import android.os.Bundle; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ListView; import java.util.ArrayList; public class Coins extends android.support.v4.app.Fragment{ @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.currency_list, container, false); final ArrayList<CoinObject> coins = new ArrayList<Currency>(); coins.add(new CoinObject(1, "India", 1947)); coins.add(new CoinObject(1, "India", 1947)); CoinAdapter itemsAdapter = new CoinAdapter(this, coins); ListView listView = (ListView) findViewById(R.id.list); listView.setAdapter(itemsAdapter); return rootView; } }CoinObject.java - 这是一个自定义类，其中每个对象都包含硬币的所有细节。
package com.example.android.cotescol; import java.util.HashMap; import java.util.Locale; import java.util.Map; public class CoinObject { private final static int NO_IMAGE_AVAILABLE = R.drawable.nia; private final static String NOT_AVAILABLE = "Material Not Specified"; private final static double NOT_KNOWN = 0.00; private int denomination; private String country; private String countryCode; private int year; private int obverseImageResourceId = NO_IMAGE_AVAILABLE; private int reverseImageResourceId = NO_IMAGE_AVAILABLE; private String material = NOT_AVAILABLE; private double diameter = NOT_KNOWN; private double weight = NOT_KNOWN; private double thickness = NOT_KNOWN; private double value = NOT_KNOWN; public CoinObject(int denomination, String country, int year, int obverseImageResourceId, int reverseImageResourceId , double diameter, double thickness, String material, double weight, double value) { this.denomination = denomination; this.country = country; this.year = year; this.obverseImageResourceId = obverseImageResourceId; this.reverseImageResourceId = reverseImageResourceId; this.diameter = diameter; this.thickness = thickness; this.material = material; this.weight = weight; this.value = value; this.countryCode = getCountryCode(country); } public CoinObject(int denomination, String country, int year, double diameter, double thickness, String material, double weight, double value) { this.denomination = denomination; this.country = country; this.year = year; this.diameter = diameter; this.thickness = thickness; this.material = material; this.weight = weight; this.value = value; this.countryCode = getCountryCode(country); } public CoinObject(int denomination, String country, int year) { this.denomination = denomination; this.country = country; this.year = year; this.countryCode = getCountryCode(country); } public String getCountryCode(String countryName) { // Get all country codes in a string array. String[] isoCountryCodes = Locale.getISOCountries(); Map<String, String> countryMap = new HashMap<>(); // Iterate through all country codes: for (String code : isoCountryCodes) { // Create a locale using each country code Locale locale = new Locale("", code); // Get country name for each code. String name = locale.getDisplayCountry(); // Map all country names and codes in key - value pairs. countryMap.put(name, code); } // Get the country code for the given country name using the map. // Here you will need some validation or better yet // a list of countries to give to user to choose from. String countryCode = countryMap.get(countryName); // "NL" for Netherlands. return countryCode; } public int getDenomination() { return denomination; } public int getYear() { return year; } public int getObverseImageResourceId() { return obverseImageResourceId; } public int getReverseImageResourceId() { return reverseImageResourceId; } public double getDiameter() { return diameter; } public double getWeight() { return weight; } public double getThickness() { return thickness; } public double getValue() { return value; } public String getCountry() { return country; } public String getCountryCode() { return countryCode; } public String getMaterial() { return material; } }CoinAdapter.java - 它是一个自定义的 ArrayAdapter
package com.example.android.cotescol; import android.content.Context; import android.support.annotation.NonNull; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.ArrayAdapter; import android.widget.ImageView; import android.widget.TextView; import java.util.ArrayList; public class CoinAdapter extends ArrayAdapter<CoinObject>{ public CoinAdapter(Context context, ArrayList<CoinObject> currencies) { super(context, 0, currencies); } @NonNull @Override public View getView(int position, View convertView, ViewGroup parent) { View listItemView = convertView; if (listItemView == null) { listItemView = LayoutInflater.from(getContext()).inflate(R.layout.list_item, parent, false); } CoinObject currentCoinObject = getItem(position); TextView denominationTextView = (TextView) listItemView.findViewById(R.id.denomination_text_view); denominationTextView.setText(currentCoinObject.getDenomination()); TextView countryTextView = (TextView) listItemView.findViewById(R.id.country_text_view); countryTextView.setText(currentCoinObject.getCountry() + "(" + currentCoinObject.getCountryCode() + ")"); TextView yearTextView = (TextView) listItemView.findViewById(R.id.year_text_view); yearTextView.setText(currentCoinObject.getYear()); ImageView obverseImageView = (ImageView) listItemView.findViewById(R.id.obverse_image_view); obverseImageView.setImageResource(currentCoinObject.getObverseImageResourceId()); ImageView reverseImageView = (ImageView) listItemView.findViewById(R.id.reverse_image_view); reverseImageView.setImageResource(currentCoinObject.getReverseImageResourceId()); return listItemView; } }
在 Coins.java 文件中，我在创建 CoinAdapter 类的实例时遇到错误。findViewById() 也显示为红色。错误图片
如果有人指导我以正确的方式进行操作，那将非常有帮助。提前致谢。