Question

我有一个自定义适配器的问题，用于在微调器中放置提示。我已经创建了一个扩展ArrayAdapter的类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.
}

在我的活动中，我为Create spinner

创建了一个函数

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());
}

我会为包含提示的所有微调器创建一个通用适配器。但我在此行中的AdapterSpinnerHint上收到此错误：

java.lang.ClassCastException：java.lang.String无法强制转换为java.lang.Integer

Answer 1

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

.setHint（string）需要字符串作为参数，并且您通过将字符串解析为Integer来传递Integer。

喜欢这个

<强> .setHint（的getItem（getCount将））;

当你在ArrayAdapter的构造函数中调用super并将字符串列表作为参数传递时，基本上你告诉ArrayAdapter它们在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

我改变了做法：在我的活动中：

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.
}

}

它可以工作，但是我已经将强制转换放在setHint上（（String）getItem（getCount（））因为我不能＆＃39;编译app没有。

错误＆＃34; java.lang.String无法强制转换为java.lang.Integer＆＃34;在Custom Adapter中

2 个答案: