Spinner2 基于 Spinner 1 中的选择动态更新答案

【问题标题】：Dynamic update of Spinner2 based on choice in Spinner 1Spinner2 基于 Spinner 1 中的选择动态更新
【发布时间】：2011-05-28 09:07:03
【问题描述】：

在使用此代码（改编自 here）时，我收到以下错误：

构造函数 ArrayAdapter(new AdapterView.OnItemSelectedListener(){}, int, String[]) 未定义

谁能帮助纠正这个问题？谢谢

private void setDynamicSpinnerBE() {
    beSpinner = (Spinner) findViewById(R.id.spBE);
    final String[] itemsSpinner2;
    lensSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {

        public void onItemSelected(AdapterView<?> parent, View view,
                int position, long id) {
            Integer focalLength = (Integer) parent.getAdapter().getItem(
                    position);
            itemsSpinner2 = getBellowsExtension(focalLength, maxBellows,
                    precision);

            ArrayAdapter<CharSequence> beAdapter = new ArrayAdapter<CharSequence>(
                    this, android.R.layout.simple_spinner_item,
                    itemsSpinner2);
            beAdapter
                    .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            beSpinner.setAdapter(beAdapter);

        }

        public void onNothingSelected(AdapterView<?> parent) {
            beSpinner.setAdapter(null);
        }
    }

    );
    ...
}

【问题讨论】：

标签： java android spinner dynamic

【解决方案1】：

在您的新ArrayAdapter 的构造函数中的以下行：

ArrayAdapter<CharSequence> beAdapter = new ArrayAdapter<CharSequence>(this,

this 指向你所在的OnItemSelectedListener 类的当前实例，而不是父视图，这是问题发生的地方，因为ArrayAdapter 没有匹配的构造函数。您应该尝试使用MyParentView.this（其中MyParentView 是您所在视图的名称）来传递适当的实例。

【讨论】：

太好了，谢谢。我认为这对很多初学者会很有帮助。
@keonbro 很高兴听到这个消息！
谢谢，这很有帮助。
非常感谢非常有帮助

【解决方案2】：

是的，就是这样：

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.AdapterView.OnItemSelectedListener;

public class DynamicSpinner extends Activity {
    private Spinner firstSpinner, secondSpinner;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        findViews();
        setAdapters();
        setListeners();
    }

private void findViews() {
    firstSpinner = (Spinner) findViewById(R.id.spLenses);
    secondSpinner = (Spinner) findViewById(R.id.spBE);
}

private void setAdapters() {
    ArrayAdapter<CharSequence> firstAdapter = ArrayAdapter.createFromResource(this, 
            R.array.lens_array, android.R.layout.simple_spinner_item);
    firstAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    firstSpinner.setAdapter(firstAdapter);
}

/* 
 * This is the important part. The user's choice in Spinner1 is passed to 
 * the procedure getDataForSecondSpinner () which creates an array shown in Spinner2  
 */
private void setListeners() {
    firstSpinner.setOnItemSelectedListener( new OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            String userChoiceSpinner1 =  (String) parent.getSelectedItem(); 
            String[] itemsSpinner2 = getDataForSecondSpinner (Integer.parseInt(userChoiceSpinner1)); 

            ArrayAdapter<CharSequence> secondAdapter = new ArrayAdapter<CharSequence>(DynamicSpinner.this, 
                    android.R.layout.simple_spinner_item, itemsSpinner2);
            secondAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);       
            secondSpinner.setAdapter(secondAdapter);                
        }
        public void onNothingSelected(AdapterView<?> parent) {
            secondSpinner.setAdapter(null);
        }
      }
    );

    secondSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
        public void onItemSelected(AdapterView<?> parent, View v, int position, long id) {
        }
        public void onNothingSelected (AdapterView<?> parent) {
        }
      }
    );
}

/*
 * Returns an array based on user choice in Spinner 1 
 */
private String[] getDataForSecondSpinner (int userChoiceSpinnerOne) { 
    //some arbitrary parameters needed for my example, ignore...
    int param2 = 330;
    double param3 = 0.17;
    int array_index = 0;

    int inputUserChoice = userChoiceSpinnerOne;

    float param5 =  (float) ( (float) param2 / (float)userChoiceSpinnerOne  - 1); 
    int array_size = (int) (Math.round(param5  / param3) + 2);
    String[] arrayBE= new String[array_size];

    while (inputUserChoice <= param2) {
        inputUserChoice = (int) (userChoiceSpinnerOne * (param3 * array_index + 1));
        if (inputUserChoice <= param2) { 
            arrayBE[array_index] = String.valueOf(inputUserChoice);
        }
        else {
            arrayBE[array_index] = String.valueOf(param2);
        }
        array_index = array_index + 1;
        }

    return arrayBE;
}


}

【讨论】：