Android Studio 中的交互式微调器

Question

我现在正在使用 Android Studio 开发一个移动应用程序。我想构建两个交互式微调器。 SQLite 数据库用于获取要显示的项目。我试图将第一个微调器的选定项目存储在字符串中。如果第一个微调器中的选定项目='1'，则第二个微调器设置适配器以显示相关项目。但是，结果显示交互失败。

    b_spinner.setEnabled(false);

    mAList =mDBHelper.getListA();
    a_adapter=new ListAAdapter(this, mAList);

    mBList =mDBHelper.getListB();
    b_adapter=new ListBAdapter(this, mBList);

    a_spinner.setAdapter(a_adapter);
    final String a_selected = ((Location)a_spinner.getSelectedItem()).getA();
    a_spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
            if(a_selected.equals("1")){
                b_spinner.setEnabled(true);
                b_spinner.setAdapter(b_adapter);
            }
        }
        @Override
        public void onNothingSelected(AdapterView<?> parent) {
        }
    });

我是 Android 应用程序开发的新手，我想问一下是否有更好的想法来构建多个交互式微调器。谢谢！

Answer 1

试试这个

     b_spinner.setEnabled(false);
        mAList =mDBHelper.getListA();
        a_adapter=new ListAAdapter(this, mAList);

        mBList =new ArrayList();
        b_adapter=new ListBAdapter(this, mBList);
        b_spinner.setAdapter(b_adapter);
        a_spinner.setAdapter(a_adapter);
        final String a_selected = ((Location)a_spinner.getSelectedItem()).getA();
        a_spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
                switch(position){
                   case 1:
                        b_spinner.setEnabled(true);
                        mBList.clear();
                        mBList.addAll(mDBHelper.getListB());
                        b_adapter.notifyDataSetChanged();
                    break;
                }
            }
            @Override
            public void onNothingSelected(AdapterView<?> parent) {
            }
        });

Answer 2

This will work :

import java.util.ArrayList;
import java.util.List;
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.Toast;
import android.widget.AdapterView.OnItemSelectedListener;

class MainActivity extends Activity implements OnItemSelectedListener{



    Spinner spinner,spinner2;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Spinner element
         spinner = (Spinner) findViewById(R.id.spinner);
         spinner2 = (Spinner) findViewById(R.id.spinner2);

        // Spinner click listener
        spinner.setOnItemSelectedListener(this);
        spinner2.setOnItemSelectedListener(this);

        // Spinner Drop down elements
        List<String>  categories = new ArrayList<String>();
        categories.add("Automobile");
        categories.add("Business_Services");
        categories.add("Computers");
        categories.add("Education");
        categories.add("Personal");
        categories.add("Travel");





        // Creating adapter for spinner
        ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories);

        // Drop down layout style - list view with radio button
        dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

        // attaching data adapter to spinner
        spinner.setAdapter(dataAdapter);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        // On selecting a spinner item
        String item = parent.getItemAtPosition(position).toString();

        if(item.equals("Automobile")){

            List<String>  categories2 = new ArrayList<String>();
            categories2.add("1");
            categories2.add("2 Services");
            categories2.add("3");
            categories2.add("4");
            categories2.add("5");
            categories2.add("6");
            Toast.makeText(parent.getContext(), "Selected: " + item, Toast.LENGTH_LONG).show();
            ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories2);

            // Drop down layout style - list view with radio button
            dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

            // attaching data adapter to spinner
            spinner2.setAdapter(dataAdapter);
        }
        else if(item.equals("Business_Services")){

            List<String>  categories3 = new ArrayList<String>();
            categories3.add("11");
            categories3.add("22 Services");
            categories3.add("33");
            categories3.add("44");
            categories3.add("55");
            categories3.add("66");
            Toast.makeText(parent.getContext(), "Selected: " + item, Toast.LENGTH_LONG).show();
            ArrayAdapter<String> dataAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item, categories3);

            // Drop down layout style - list view with radio button
            dataAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);

            // attaching data adapter to spinner
            spinner2.setAdapter(dataAdapter);
        }

        // Showing selected spinner item

    }



    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub
    }
}

和 XML：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:padding="10dip"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dip"
        android:text="Category:"
        android:layout_marginBottom="5dp"/>

    <Spinner
    android:id="@+id/spinner"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    />

    <Spinner
        android:id="@+id/spinner2"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />

</LinearLayout>