在Java中使用Android ListActivities传递数据

时间：2012-04-05 23:21:14

标签： java android listview listactivity

我无法使此代码生效。

基本上我从一个列表活动转到另一个列表活动，并将文本从列表项通过活动的意图传递到新列表视图，然后在新列表活动中检索该文本，然后根据值执行http请求那个清单项目。

Log Cat 

04-05 17:47:32.370: E/AndroidRuntime(30135): FATAL EXCEPTION: main
04-05 17:47:32.370: E/AndroidRuntime(30135): java.lang.ClassCastException:android.widget.LinearLayout
04-05 17:47:32.370: E/AndroidRuntime(30135): at com.thickcrustdesigns.ufood.CatogPage$1.onItemClick(CatogPage.java:66)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.AdapterView.performItemClick(AdapterView.java:284)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.ListView.performItemClick(ListView.java:3731)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.widget.AbsListView$PerformClick.run(AbsListView.java:1959)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Handler.handleCallback(Handler.java:587)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Handler.dispatchMessage(Handler.java:92)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.os.Looper.loop(Looper.java:130)
04-05 17:47:32.370: E/AndroidRuntime(30135): at android.app.ActivityThread.main(ActivityThread.java:3691)
04-05 17:47:32.370: E/AndroidRuntime(30135): at java.lang.reflect.Method.invokeNative(Native Method)
04-05 17:47:32.370: E/AndroidRuntime(30135): at java.lang.reflect.Method.invoke(Method.java:507)
04-05 17:47:32.370: E/AndroidRuntime(30135): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:907)
04-05 17:47:32.370: E/AndroidRuntime(30135): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:665)
04-05 17:47:32.370: E/AndroidRuntime(30135): at dalvik.system.NativeStart.main(Native Method)

ListActivity 1 

package com.thickcrustdesigns.ufood;

import java.util.ArrayList;
import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;

public class CatogPage extends ListActivity {

    ListView listView1;
    Button btn_bk;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.definition_main);

        btn_bk = (Button) findViewById(R.id.btn_bk);

        listView1 = (ListView) findViewById(android.R.id.list);

        ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>();

        nvp.add(new BasicNameValuePair("request", "categories"));

        ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp);

        String[] defs = new String[jsondefs.size()];

        for (int i = 0; i < jsondefs.size(); i++) {
            try {
                defs[i] = jsondefs.get(i).getString("Name");
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list,
                defs);

        listView1.setAdapter(adapter);
        ListView lv = getListView();
        lv.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                TextView tv = (TextView) view;
                String p = tv.getText().toString();
                Intent i = new Intent(getApplicationContext(), Results.class);
                i.putExtra("category", p);
                startActivity(i);
            }
        });

        btn_bk.setOnClickListener(new View.OnClickListener() {
            public void onClick(View arg0) {
                Intent i = new Intent(getApplicationContext(),
                        UFoodAppActivity.class);
                startActivity(i);
            }
        });

    }

}


**ListActivity 2**

package com.thickcrustdesigns.ufood;

    import java.util.ArrayList;
    import org.apache.http.NameValuePair;
    import org.apache.http.message.BasicNameValuePair;
    import org.json.JSONException;
    import org.json.JSONObject;
    import android.app.ListActivity;
    import android.os.Bundle;
    import android.widget.ListView;

    public class Results extends ListActivity {

    ListView listView1;

    enum Category {
        Chicken, Beef, Chinese, Cocktails, Curry, Deserts, Fish, ForOne {
            public String toString() {
                return "For One";
            }
        },
        Lamb, LightBites {
            public String toString() {
                return "Light Bites";
            }
        },
        Pasta, Pork, Vegetarian
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        this.setContentView(R.layout.definition_main);

        listView1 = (ListView) findViewById(android.R.id.list);

        Bundle data = getIntent().getExtras();
        String category = data.getString("category");

        Category cat = Category.valueOf(category);

        String value = null;

        switch (cat) {
        case Chicken:
            value = "Chicken";
            break;
        case Beef:
            value = "Beef";
            break;
        case Chinese:
            value = "Chinese";
            break;
        case Cocktails:
            value = "Cocktails";
            break;
        case Curry:
            value = "Curry";
            break;
        case Deserts:
            value = "Deserts";
            break;
        case Fish:
            value = "Fish";
            break;
        case ForOne:
            value = "ForOne";
            break;
        case Lamb:
            value = "Lamb";
            break;
        case LightBites:
            value = "LightBites";
            break;
        case Pasta:
            value = "Pasta";
            break;
        case Pork:
            value = "Pork";
            break;
        case Vegetarian:
            value = "Vegetarian";
        }

        ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>();

        nvp.add(new BasicNameValuePair("request", "category"));

        nvp.add(new BasicNameValuePair("cat", value));

        ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp);

        String[] defs = new String[jsondefs.size()];

        for (int i = 0; i < jsondefs.size(); i++) {
            try {
                defs[i] = jsondefs.get(i).getString("Name");
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list,
                defs);
        listView1.setAdapter(adapter);

           }

       }

请求 

package com.thickcrustdesigns.ufood;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONObject;
import android.content.Context;
import android.util.Log;
import android.widget.Toast;

public class Request {

    @SuppressWarnings("null")
    public static ArrayList<JSONObject> fetchData(Context context,
            ArrayList<NameValuePair> nvp) {
        ArrayList<JSONObject> listItems = new ArrayList<JSONObject>();
        InputStream is = null;
        try {
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(
                    "http://co350-11d.projects02.glos.ac.uk/php/database.php");
            httppost.setEntity(new UrlEncodedFormEntity(nvp));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
        } catch (Exception e) {
            Log.e("log_tag", "Error in http connection" + e.toString());
        }

        // convert response to string

        String result = "";
        try {
            BufferedReader reader = new BufferedReader(new InputStreamReader(
                    is, "iso-8859-1"), 8);
            InputStream stream = null;
            StringBuilder sb = null;

            while ((result = reader.readLine()) != null) {
                sb.append(result + "\n");
            }

            stream.close();
            result = sb.toString();

        } catch (Exception e) {
            Log.e("log_tag", "Error converting result " + e.toString());
        }

        try {
            JSONArray jArray = new JSONArray(result);

            for (int i = 0; i < jArray.length(); i++) {

                JSONObject jo = jArray.getJSONObject(i);

                listItems.add(jo);

            }

        } catch (Exception e) {
            Toast.makeText(context.getApplicationContext(), "None Found!",
                    Toast.LENGTH_LONG).show();

        }
        return listItems;

    }

}

package com.thickcrustdesigns.ufood;

import java.util.ArrayList;

import org.apache.http.NameValuePair;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ListView;

public class Results extends ListActivity {

    ListView listView1;

    enum Category {
        Chicken, Beef, Chinese, Cocktails, Curry, Deserts, Fish, ForOne {
            public String toString() {
                return "For One";
            }
        },
        Lamb, LightBites {
            public String toString() {
                return "Light Bites";
            }
        },
        Pasta, Pork, Vegetarian
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        this.setContentView(R.layout.definition_main);

        listView1 = (ListView) findViewById(android.R.id.list);

        Bundle data = getIntent().getExtras();
        String category = data.getString("category");

        Category cat = Category.valueOf(category);

        String value = null;

        switch (cat) {
        case Chicken:
            value = "Chicken";
            break;
        case Beef:
            value = "Beef";
            break;
        case Chinese:
            value = "Chinese";
            break;
        case Cocktails:
            value = "Cocktails";
            break;
        case Curry:
            value = "Curry";
            break;
        case Deserts:
            value = "Deserts";
            break;
        case Fish:
            value = "Fish";
            break;
        case ForOne:
            value = "ForOne";
            break;
        case Lamb:
            value = "Lamb";
            break;
        case LightBites:
            value = "LightBites";
            break;
        case Pasta:
            value = "Pasta";
            break;
        case Pork:
            value = "Pork";
            break;
        case Vegetarian:
            value = "Vegetarian";
        }

        ArrayList<NameValuePair> nvp = new ArrayList<NameValuePair>();

        nvp.add(new BasicNameValuePair("request", "category"));

        nvp.add(new BasicNameValuePair("cat", value));

        ArrayList<JSONObject> jsondefs = Request.fetchData(this, nvp);

        String[] defs = new String[jsondefs.size()];

        for (int i = 0; i < jsondefs.size(); i++) {
            try {
                defs[i] = jsondefs.get(i).getString("Name");
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }

        uFoodAdapter adapter = new uFoodAdapter(this, R.layout.definition_list,
                defs);
        listView1.setAdapter(adapter);

    }

}

2 个答案:

答案 0 :(得分：0)

您的问题可能在TextView tv = (TextView) view;，LinearLayout TextView {{1}}

答案 1 :(得分：0)

基本上我通过使用onitemclick的position参数来改变它检索要发送的数据的方式，以从用于填充列表视图的数组中获取项目。

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