自定义适配器中的错误 "java.lang.String cannot be cast to java.lang.Integer"

Question

我在微调器中放置提示的自定义适配器有问题。我制作了一个扩展 ArrayAdapter:

的 class AdapterSpinnerhint

public class AdapterSpinnerHint extends ArrayAdapter {
int labelHint;
int textViewId;
int layout;
ArrayList<String> mItems;
Context context;

public AdapterSpinnerHint(Context context, int spinner_layout, int field, ArrayList<String> list, int label) {
    super(context, spinner_layout, list);
    textViewId = field;
    labelHint = label;
    layout = spinner_layout;
    mItems=list;
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View v;
    LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    v = inflater.inflate(layout, null);
    if (position == getCount()) {
        ((TextView)v.findViewById(textViewId)).setText(labelHint);
        ((TextView)v.findViewById(textViewId)).setHint((Integer) getItem(getCount())); //"Hint to be displayed"
    }

    return v;
}
@Override
public int getCount() {
    return mItems.size()-1; // you dont display last item. It is used as hint.
}

在我的 activity 中，我创建了一个用于创建微调器的函数

private void createSpinnerCustomer(JSONArray customers) {
    Spinner spinner = (Spinner) findViewById(R.id.customers_spinner);



    ArrayList<String> customersList=new ArrayList<String>();
    for(int i=0;i<customers.length();i++){
        try {
            customersList.add(customers.getJSONObject(i).getString("name"));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
    customersList.add(String.valueOf(R.string.customer_label));
    assert spinner != null;
    AdapterSpinnerHint adapter=new AdapterSpinnerHint(
            getApplicationContext(), R.layout.spinner_layout, R.id.txt, customersList, R.string.customer_label);
    spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view,
                                   int pos, long id) {
        }

        public void onNothingSelected(AdapterView<?> parent) {
        }

    });

    spinner.setAdapter(adapter);
    spinner.setSelection(adapter.getCount());
}

我将为所有包含提示的微调器创建一个通用适配器。但是我在这一行的 AdapterSpinnerHint 上收到此错误：

java.lang.ClassCastException: java.lang.String 无法转换为 java.lang.Integer

Answer 1

在您的函数中 - getView 看到这一行 - .setHint((Integer)getItem(getCount()));

.setHint(string) 需要字符串作为参数，您通过将字符串解析为整数来传递整数。

这样做

.setHint(getItem(getCount));

当您在 ArrayAdapter 的构造函数中调用 super 并将字符串列表作为参数传递时，基本上您是在告诉 ArrayAdapter 列表中的对象类型将是 String。所以当你执行 getItem() 时，它将返回一个 String

Answer 2

我改变了方法：在我的 activity:

private void createSpinnerCustomer(JSONArray customers) {
    Spinner spinner = (Spinner) findViewById(R.id.customers_spinner);
    AdapterSpinnerHint adapter2 = new AdapterSpinnerHint(ActivityActivity.this, android.R.layout.simple_spinner_dropdown_item, "Customers", customers, "name");
    adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    assert spinner != null;
    spinner.setAdapter(adapter2);
    spinner.setSelection(adapter2.getCount());


}

我的适配器：

public class AdapterSpinnerHint extends ArrayAdapter {
String labelHint;

JSONArray mItems;
String property;

public AdapterSpinnerHint(Context context, int spinner_layout, String label, JSONArray list, String getValue) {

    super(context, spinner_layout);
    labelHint = label;
    mItems = list;
    property = getValue;
    addValue(mItems);
}

private void addValue(JSONArray customers) {
    for(int i=0;i<customers.length();i++){
        try {
            this.add(customers.getJSONObject(i).getString(property));
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

    this.add(labelHint);
}


@Override
public View getView(int position, View convertView, ViewGroup parent) {

    View v = super.getView(position, convertView, parent);
    if (position == getCount()) {
        ((TextView)v.findViewById(android.R.id.text1)).setText("");
        ((TextView)v.findViewById(android.R.id.text1)).setHint((String) getItem(getCount())); //"Hint to be displayed"
    }

    return v;
}

@Override
public int getCount() {
    return super.getCount()-1; // you dont display last item. It is used as hint.
}

}

它有效，但我必须对 setHint((String) getItem(getCount()) 进行强制转换因为没有它我就无法编译应用程序。

自定义适配器中的错误 "java.lang.String cannot be cast to java.lang.Integer"

Error "java.lang.String cannot be cast to java.lang.Integer" In Custom Adapter

android

hint

android-arrayadapter

android-spinner