android - HashMap 无法转换为 java.lang.string

Question

我正在尝试从 ListView 中获取值。 ListView 由 hashmap 类型的数组列表设置。所以，如果我试图获取字符串中的值，我会收到错误消息 HashMap cannot be cast to java.lang.string

细节1.java

package com.example.festipedia_logo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import com.actionbarsherlock.app.SherlockFragment;
import com.actionbarsherlock.app.SherlockListFragment;
//import com.example.festipedia_logo.Searchpage.LoadAllProducts;


//import com.example.connection.disp;

import android.app.Activity;
import android.app.Fragment;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

public class details1 extends SherlockFragment {
    ArrayAdapter<String> adapter;
    String[] city;
    // Progress Dialog
    private ProgressDialog pDialog;

    // Creating JSON Parser object
    JSONParser jParser = new JSONParser();
EditText b;
    ArrayList<HashMap<String, String>> productsList;

    // url to get all products list
    private static String url_all_products = "http://192.168.43.77/festipedia/get_all_products.php";
Button a;

    // JSON Node names
    private static final String TAG_SUCCESS = "success";
    private static final String TAG_PRODUCTS = "products";
    private static final String TAG_NAME = "eventname";

    // products JSONArray
    JSONArray products = null;
ListView l;
Spinner spinner;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.second);
        View rootView = inflater.inflate(R.layout.home2, container, false);

    //  setContentView(R.layout.all_products);
        l = (ListView) rootView.findViewById(R.id.list);

        // Hashmap for ListView
        productsList = new ArrayList<HashMap<String, String>>();
        new LoadAllProducts().execute();
        l.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // Do something   
                //  String  itemValue    = (String) l.getItemAtPosition(position);
                 // Intent intent = new Intent(getActivity().getBaseContext(),
                 //           MainActivity.class);
                   // intent.putExtra("message", itemValue);
                 //   getActivity().startActivity(intent);

               //     Bundle args = new Bundle();
             //       args.putString("doctor_id",itemValue);    
           //         details1 newFragment = new details1 ();
          //          newFragment.setArguments(args);
                //String str = ((TextView)childView).getText().toString();

                       //MainActivity ob=new MainActivity();
                      // ListView Clicked item index
                      int itemPosition     = position;

                      // ListView Clicked item value
                      String  itemValue    = (String) l.getItemAtPosition(position);  
                final FragmentTransaction ft = getFragmentManager().beginTransaction(); 
                    ft.replace(R.id.content_frame,new SlidetabTesting(itemValue) , "Fest Content"); 
                    ft.commit();
            }

        });

        return rootView;
                    }

    /**
     * Background Async Task to Load all product by making HTTP Request
     * */
    class LoadAllProducts extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();

            pDialog = new ProgressDialog(getActivity());
            pDialog.setMessage("Loading products. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        /**
         * getting All products from url
         * */
        protected String doInBackground(String... args) {
            // Building Parameters
            List<NameValuePair> params = new ArrayList<NameValuePair>();


            // getting JSON string from URL
            JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

        //  Log.d("All Products: ", json.toString());

            try {
                // Checking for SUCCESS TAG
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // products found
                    // Getting Array of Products
                    products = json.getJSONArray(TAG_PRODUCTS);

                    // looping through All Products
                    for (int i = 0; i < products.length(); i++) {
                        JSONObject c = products.getJSONObject(i);

                        // Storing each json item in variable

                        String name = c.getString(TAG_NAME);

                        //l.setFilterText(id);
                        // creating new HashMap
                        HashMap<String, String> map = new HashMap<String, String>();

                        // adding each child node to HashMap key => value
                        map.put(TAG_NAME, name);

                        // adding HashList to ArrayList
                        productsList.add(map);
                    }
                } else {
                    // no products found
                    // Launch Add New product Activity
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            // dismiss the dialog after getting all products
            pDialog.dismiss();
            // updating UI from Background Thread
            getActivity().runOnUiThread(new Runnable() {
                public void run() {
                    /**
                     * Updating parsed JSON data into ListView
                     * */
                    ListAdapter adapter = new SimpleAdapter(
                            getActivity(), productsList,
                            R.layout.list_item, new String[] {
                                    TAG_NAME},
                            new int[] {  R.id.name });
                    // updating listview
                    l.setAdapter(adapter);
                }
            });


        }

    }
}

洛格卡特

03-30 20:03:43.341: E/ViewRootImpl(8395): sendUserActionEvent() mView == null
03-30 20:03:47.111: E/ViewRootImpl(8395): sendUserActionEvent() mView == null
03-30 20:03:49.416: E/AndroidRuntime(8395): FATAL EXCEPTION: main
03-30 20:03:49.416: E/AndroidRuntime(8395): Process: com.example.festipedia_logo, PID: 8395
03-30 20:03:49.416: E/AndroidRuntime(8395): java.lang.ClassCastException: java.util.HashMap cannot be cast to java.lang.String
03-30 20:03:49.416: E/AndroidRuntime(8395):     at com.example.festipedia_logo.details1$1.onItemClick(details1.java:103)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.widget.AdapterView.performItemClick(AdapterView.java:308)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.widget.AbsListView.performItemClick(AbsListView.java:1483)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.widget.AbsListView$PerformClick.run(AbsListView.java:3485)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.widget.AbsListView$3.run(AbsListView.java:4843)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.os.Handler.handleCallback(Handler.java:733)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.os.Handler.dispatchMessage(Handler.java:95)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.os.Looper.loop(Looper.java:157)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at android.app.ActivityThread.main(ActivityThread.java:5356)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at java.lang.reflect.Method.invokeNative(Native Method)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at java.lang.reflect.Method.invoke(Method.java:515)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081)
03-30 20:03:49.416: E/AndroidRuntime(8395):     at dalvik.system.NativeStart.main(Native Method)

有什么方法可以检索值

Answer 1

java.lang.ClassCastException: java.util.HashMap cannot be cast to java.lang.String

这一行就是问题所在

String  itemValue = (String) l.getItemAtPosition(position); 

更改为

l.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,int position, long id) {

HashMap<String,String> map =(HashMap<String,String>)l.getItemAtPosition(position);
String value = map.get(TAG_SUCCESS);
Sting products = map.get(TAG_PRODUCTS);
String name= map.get(TAG_NAME);
... // rest of the code
}