Question

我正在尝试使用自定义适配器实现listview。问题是每当触发onItemClickListener事件时它都会崩溃。

java.lang.ClassCastException：imp.translator.diana.lang.CardItemData 无法强制转换为java.lang.String at imp.translator.diana.lang.Speak $ 1.onItemClick（Speak.java:41）在android.widget.AdapterView.performItemClick

这是我的班级：

    final ListView list = (ListView) findViewById(R.id.list_view);

    list.addHeaderView(new View(this));
    list.addFooterView(new View(this));

    BaseInflaterAdapter<CardItemData> adapter = new BaseInflaterAdapter<CardItemData>(new CardInflater());

    CardItemData data = new CardItemData("Translate");
    adapter.addItem(data, false);
    CardItemData data2 = new CardItemData("Voice to Text");
    adapter.addItem(data2, false);
    CardItemData data3 = new CardItemData("Record");
    adapter.addItem(data3, false);
    CardItemData data4 = new CardItemData("Info");
    adapter.addItem(data4, false);

    list.setAdapter(adapter);

    list.setClickable(true);
    list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView myAdapter, View myView, int position, long mylng) {
            String selectedFromList = (String) (myAdapter.getItemAtPosition(position));
        }
    });

和我的适配器：

public class BaseInflaterAdapter<T> extends BaseAdapter
{
    private List<T> m_items = new ArrayList<T>();
    private IAdapterViewInflater<T> m_viewInflater;

    public BaseInflaterAdapter(IAdapterViewInflater<T> viewInflater)
    {
        m_viewInflater = viewInflater;
    }

    public BaseInflaterAdapter(List<T> items, IAdapterViewInflater<T> viewInflater)
    {
        m_items.addAll(items);
        m_viewInflater = viewInflater;
    }

    public void setViewInflater(IAdapterViewInflater<T> viewInflater, boolean notifyChange)
    {
        m_viewInflater = viewInflater;

        if (notifyChange)
            notifyDataSetChanged();
    }

    public void addItem(T item, boolean notifyChange)
    {
        m_items.add(item);

        if (notifyChange)
            notifyDataSetChanged();
    }

    public void addItems(List<T> items, boolean notifyChange)
    {
        m_items.addAll(items);

        if (notifyChange)
            notifyDataSetChanged();
    }

    public void clear(boolean notifyChange)
    {
        m_items.clear();

        if (notifyChange)
            notifyDataSetChanged();
    }

    @Override
    public int getCount()
    {
        return m_items.size();
    }

    @Override
    public Object getItem(int pos)
    {
        return getTItem(pos);
    }

    public T getTItem(int pos)
    {
        return m_items.get(pos);
    }

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

    @Override
    public View getView(int pos, View convertView, ViewGroup parent)
    {
        return m_viewInflater != null ? m_viewInflater.inflate(this, pos, convertView, parent) : null;
    }
}

和CardItemData：

public class CardItemData
{
    private String m_text1;
    public CardItemData(String text1)
    {
        m_text1 = text1;
    }
    public String getText1()
    {
        return m_text1;
    }
}

知道这里可能有什么问题吗？

Answer 1

知道这里可能有什么问题吗？

您的getItem正在返回T，在您的情况下，这是CardItemData的实例，但在此处：

 String selectedFromList = (String) (myAdapter.getItemAtPosition(position));

您将其投射到String。您可能希望将其强制转换为CardItemData。顺便说一句，Java支持协变返回类型，因此您应该能够使用

@Override
public T getItem(int pos) {
    return m_items.get(pos);
}

Answer 2

它是一个类型转换问题，你是类型转换＆＃34; CardItemData＆＃34;到＆＃34;字符串＆＃34;

String selectedFromList =（String）（myAdapter.getItemAtPosition（position））;

使用＆＃34; getItem＆＃34;获得点击的方法＆＃34; CardItemData＆＃34;项目

检查下面给出的链接 Android Docs link

ListView - setOnItemClickListener不工作

2 个答案: