Question

我需要从sqlite数据库加载大型数据集。这将花费太多时间来加载数据。因此我使用LoadMorelistView库来加载分页。

我按照下面的链接并成功加载来自硬编码列表的数据。 pull to refresh and loadmore listview like facebook

但是当我尝试从sqlite数据库加载时出现以下错误。

//构造函数ArrayAdapter（Activity，int，ArrayList）是Undefined

我搜索了谷歌以及stackoverflow。但无法找到解决方案。

请找到我用来加载数据的代码段，

列表加载片段的代码。（FragmentThree.java）

package com.load.more.list.view;

import java.util.ArrayList;

import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;

import com.costum.android.widget.LoadMoreListView;
import com.costum.android.widget.LoadMoreListView.OnLoadMoreListener;
import com.load.more.list.model.Customer;
import com.load.more.list.data.CustomerDS;
import com.load.more.list.data.DatabaseHelper;

import android.app.Fragment;

import com.load.more.list.control.CustomerAdapter;

public class FragmentThree extends Fragment {

    View view;

    LoadMoreListView lyt;
    ArrayAdapter<String> files;
    ArrayList<Customer> mListItems;
    CustomerDS customerDS;
    private DatabaseHelper dbHelper;

    private int visibleThreshold = 20;
    private int currentPage = 0;
    private int previousTotal = 0;
    private int firstVisibleItem = 0;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        view = inflater.inflate(R.layout.fragment_three, container, false);

        lyt = (LoadMoreListView) view.findViewById(R.id.lvRouteCustomers);

        mListItems = customerDS.getAllCustomersFromTo(visibleThreshold,
                firstVisibleItem);

        // Following Error Thrown from here
        // The constructor ArrayAdapter<String>(Activity, int,
        // ArrayList<Customer>) is Undefined
        files = new ArrayAdapter<String>(getActivity(),
                android.R.layout.simple_list_item_1, mListItems);
        lyt.setAdapter(files);

        lyt.setOnLoadMoreListener(new OnLoadMoreListener() {

            @Override
            public void onLoadMore() {
                // TODO Auto-generated method stub
                new LoadMoreDataTask().execute();
            }
        });

        return view;
    }

    private class LoadMoreDataTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected Void doInBackground(Void... params) {

            if (isCancelled()) {
                return null;
            }

            // Simulates a background task
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }

            // Following Error Thrown from here
            // The constructor ArrayAdapter<String>(Activity, int,
            // ArrayList<Customer>) is Undefined
            files = new ArrayAdapter<String>(getActivity(),
                    android.R.layout.simple_list_item_1, mListItems);
            lyt.setAdapter(files);

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {

            files.notifyDataSetChanged();

            // Call onLoadMoreComplete when the LoadMore task, has finished
            lyt.onLoadMoreComplete();

            super.onPostExecute(result);
        }

        @Override
        protected void onCancelled() {
            // Notify the loading more operation has finished
            lyt.onLoadMoreComplete();
        }
    }

}

数据库助手类的代码。（DatabaseHelper）

package com.load.more.list.data;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DatabaseHelper extends SQLiteOpenHelper {

    //database information
    private static final String DATABASE_NAME = "fmcgDB.db"; 
    private static final int DATABASE_VERSION = 1;


    //TABLES

    //Customer table
    public static final String TABLE_CUSTOMER = "customer";
    public static final String CUSTOMER_ID = "customer_id";
    public static final String CUSTOMER_NO = "customer_no";
    public static final String CUSTOMER_NAME = "customer_name";
    public static final String CUSTOMER_CONTACT_PERSON = "customer_contact_person";
    public static final String CUSTOMER_TELEPHONE_NO = "customer_telephone_no";
    public static final String CUSTOMER_ADDRESS = "customer_address";
    public static final String CUSTOMER_LONGITUDE = "customer_longitude";
    public static final String CUSTOMER_LATITUDE = "customer_latitude";
    public static final String CUSTOMER_TLP = "customer_tlp";
    public static final String CUSTOMER_REP_ID = "customer_rep_id";
    public static final String CUSTOMER_CATEGORY_ID = "cc_id";
    public static final String CUSTOMER_OUTLET_TYPE_ID = "ot_id";
    public static final String CUSTOMER_PERIPHERY_TYPE_ID = "pt_id";
    public static final String CUSTOMER_VOLUME_ID = "volume_id";
    public static final String CUSTOMER_MARKET_ID = "market_id";

    private static final String CREATE_CUSTOMER_TABLE = "CREATE TABLE " + TABLE_CUSTOMER + " ("
            + CUSTOMER_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
            + CUSTOMER_NO + " TEXT, "
            + CUSTOMER_NAME + " TEXT, "
            + CUSTOMER_CONTACT_PERSON + " TEXT, "
            + CUSTOMER_TELEPHONE_NO + " TEXT, "
            + CUSTOMER_ADDRESS + " TEXT, "
            + CUSTOMER_LONGITUDE + " REAL, "
            + CUSTOMER_LATITUDE + " REAL, "
            + CUSTOMER_TLP + " INTEGER, "
            + CUSTOMER_REP_ID + " INTEGER, "
            + CUSTOMER_CATEGORY_ID + " INTEGER, "
            + CUSTOMER_OUTLET_TYPE_ID + " INTEGER, "
            + CUSTOMER_PERIPHERY_TYPE_ID + " INTEGER, "
            + CUSTOMER_VOLUME_ID + " INTEGER, "
            + CUSTOMER_MARKET_ID + " INTEGER "
            +");";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase arg0) { // this order must be followed when creating tables
        arg0.execSQL(CREATE_CUSTOMER_TABLE);

    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
        arg0.execSQL("DROP TABLE IF EXISTS " + CREATE_CUSTOMER_TABLE);
        onCreate(arg0);

    }

}

sqlite数据加载的代码。（CustomerDS.java）

package com.load.more.list.data;

import java.util.ArrayList;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;

import com.load.more.list.model.Customer;

public class CustomerDS {

    private SQLiteDatabase fmcgDB;
    private DatabaseHelper dbHelper;
    Context context;

    public CustomerDS(Context context) {
        this.context = context;
        dbHelper = new DatabaseHelper(context);
    }

    public void open() throws SQLException {
        fmcgDB = dbHelper.getWritableDatabase();
    }

    public ArrayList<Customer> getAllCustomersFromTo(int limit, int offset) {
        if (fmcgDB == null) {
            open();
        } else if (!fmcgDB.isOpen()) {
            open();
        }
        ArrayList<Customer> customersList = new ArrayList<Customer>();

        // Newly Added
        String selectQuery = "SELECT * FROM " + dbHelper.TABLE_CUSTOMER
                + " LIMIT " + limit + " OFFSET " + offset +"";

        Cursor cursor = null;
        try{
            cursor = fmcgDB.rawQuery(selectQuery, null);

        /*cursor = fmcgDB.query(dbHelper.TABLE_CUSTOMER, null, null, null,
                    null, null, null);
        */  
        while (cursor.moveToNext()) {
            Customer customer = new Customer();
            customer.setCustomer_id(cursor.getInt(cursor.getColumnIndex(dbHelper.CUSTOMER_ID)));
            customer.setCustomer_no(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_NO))));
            customer.setCustomer_name(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_NAME))));
            customer.setCustomer_contact_person(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_CONTACT_PERSON))));
            customer.setCustomer_telephone_no(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_TELEPHONE_NO))));
            customer.setCustomer_address(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_ADDRESS))));
            customer.setCustomer_longitude(cursor.getDouble((cursor.getColumnIndex(dbHelper.CUSTOMER_LONGITUDE))));
            customer.setCustomer_latitude(cursor.getDouble((cursor.getColumnIndex(dbHelper.CUSTOMER_LATITUDE))));
            int TLP = cursor.getInt((cursor.getColumnIndex(dbHelper.CUSTOMER_TLP)));
            if(TLP == 0){
                customer.setCustomer_TLP_member(true);
            }else{
                customer.setCustomer_TLP_member(false);
            }

            customersList.add(customer);
        }
        }
        finally {  
            if (cursor!=null) {
                cursor.close();
            }
            fmcgDB.close();
            return customersList;
            }
    }
}

适配器类的代码。（CustomerAdapter.java）

package com.load.more.list.control;

import java.util.ArrayList;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import com.load.more.list.model.Customer;
import com.load.more.list.view.R;

    public class CustomerAdapter extends ArrayAdapter<Customer> {
        Context context;
        ArrayList<Customer> customerList;

        public CustomerAdapter(Context context, ArrayList<Customer> customerList){
            super(context, R.layout.item_customer, customerList);
            this.context = context;
            this.customerList = customerList;   
        }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {

            LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            View row = inflater.inflate(R.layout.item_customer, parent, false);
            TextView tvName = (TextView) row.findViewById(R.id.tvRouteCustomerListName);
            TextView tvMarket = (TextView) row.findViewById(R.id.tvRouteCustomerListMarket);
            TextView tvVolume = (TextView) row.findViewById(R.id.tvRouteCustomerListVolume);

            tvName.setText(customerList.get(position).getCustomer_name());

            return row;
        }
}

客户对象的代码。（Customer.java）

package com.load.more.list.model;

import java.util.ArrayList;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.content.Context;
import android.util.Log;

public class Customer {

    private static final String TAG_CUSTOMER = "customers";
    private static final String TAG_CUSTOMER_ID = "customer_id";
    private static final String TAG_CUSTOMER_NO = "CustomerCode";
    private static final String TAG_CUSTOMER_NAME = "CustomerName";
    private static final String TAG_CUSTOMER_ADDRESS = "Address1";
    private static final String TAG_CUSTOMER_CONTACT_PERSON = "ContactPersonName";
    private static final String TAG_CUSTOMER_TELEPHONE_NO = "PhoneNo";
    private static final String TAG_CUSTOMER_LATITUDE = "CustomerLatitude";
    private static final String TAG_CUSTOMER_LONGITUDE = "CustomerLongitude";
    private static final String TAG_CUSTOMER_IS_TLP = "Istlp";
    private static final String TAG_CUSTOMER_REP_ID = "";
    private static final String TAG_CUSTOMER_PT_ID = "PheriheryId";
    private static final String TAG_CUSTOMER_CATEGORY_ID = "CatrgoryId";
    private static final String TAG_CUSTOMER_OUTLETTYPE_ID = "OutletTypeId";
    private static final String TAG_CUSTOMER_VOLUME_ID = "VolumeId";
    private static final String TAG_CUSTOMER_MARKET_ID = "MarketId";


    private int customer_id;
    private String customer_no;
    private String customer_name;
    private String customer_contact_person;
    private String customer_telephone_no;
    private String customer_address;
    private double customer_longitude;
    private double customer_latitude;
    private boolean customer_TLP_member;


    public int getCustomer_id() {
        return customer_id;
    }
    public void setCustomer_id(int customer_id) {
        this.customer_id = customer_id;
    }
    public String getCustomer_name() {
        return customer_name;
    }
    public void setCustomer_name(String customer_name) {
        this.customer_name = customer_name;
    }
    public String getCustomer_contact_person() {
        return customer_contact_person;
    }
    public void setCustomer_contact_person(String customer_contact_person) {
        this.customer_contact_person = customer_contact_person;
    }
    public String getCustomer_telephone_no() {
        return customer_telephone_no;
    }
    public void setCustomer_telephone_no(String customer_telephone_no) {
        this.customer_telephone_no = customer_telephone_no;
    }
    public String getCustomer_address() {
        return customer_address;
    }
    public void setCustomer_address(String customer_address) {
        this.customer_address = customer_address;
    }
    public double getCustomer_longitude() {
        return customer_longitude;
    }
    public void setCustomer_longitude(double customer_longitude) {
        this.customer_longitude = customer_longitude;
    }
    public double getCustomer_latitude() {
        return customer_latitude;
    }
    public void setCustomer_latitude(double customer_latitude) {
        this.customer_latitude = customer_latitude;
    }

public boolean isCustomer_TLP_member() {
        return customer_TLP_member;
    }
    public void setCustomer_TLP_member(boolean customer_TLP_member) {
        this.customer_TLP_member = customer_TLP_member;
    }
    public String getCustomer_no() {
        return customer_no;
    }
    public void setCustomer_no(String customer_no) {
        this.customer_no = customer_no;
    }


}

有谁知道如何解决这个问题？如果是，请帮我解决这个问题。

提前致谢。

Answer 1

最后我解决了这个问题，。

我已将mListItems的类型更改为

ArrayList<String> mListItems;

并将getAllCustomersFromTo（）的返回类型转换为String数组。

它解决了我的问题。

更新类的最终源代码如下所示。

列表加载片段的代码。（FragmentThree.java）

package com.load.more.list.view;

import java.util.ArrayList;

import android.os.AsyncTask;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;

import com.costum.android.widget.LoadMoreListView;
import com.costum.android.widget.LoadMoreListView.OnLoadMoreListener;
import com.load.more.list.model.Customer;
import com.load.more.list.data.CustomerDS;
import com.load.more.list.data.DatabaseHelper;

import android.app.Fragment;

import com.load.more.list.control.CustomerAdapter;

public class FragmentThree extends Fragment {

    View view;

    LoadMoreListView lyt;
    ArrayAdapter<String> files;
    ArrayList<String> mListItems;
    CustomerDS customerDS;
    private DatabaseHelper dbHelper;

    private int visibleThreshold = 20;
    private int currentPage = 0;
    private int previousTotal = 0;
    private int firstVisibleItem = 0;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        view = inflater.inflate(R.layout.fragment_three, container, false);

        lyt = (LoadMoreListView) view.findViewById(R.id.lvRouteCustomers);

        mListItems = customerDS.getAllCustomersFromTo(visibleThreshold,
                firstVisibleItem);

        files = new ArrayAdapter<String>(getActivity(),
                android.R.layout.simple_list_item_1, mListItems);
        lyt.setAdapter(files);

        lyt.setOnLoadMoreListener(new OnLoadMoreListener() {

            @Override
            public void onLoadMore() {
                // TODO Auto-generated method stub
                new LoadMoreDataTask().execute();
            }
        });

        return view;
    }

    private class LoadMoreDataTask extends AsyncTask<Void, Void, Void> {

        @Override
        protected Void doInBackground(Void... params) {

            if (isCancelled()) {
                return null;
            }

            // Simulates a background task
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
            }

            files = new ArrayAdapter<String>(getActivity(),
                    android.R.layout.simple_list_item_1, mListItems);
            lyt.setAdapter(files);

            return null;
        }

        @Override
        protected void onPostExecute(Void result) {

            files.notifyDataSetChanged();

            // Call onLoadMoreComplete when the LoadMore task, has finished
            lyt.onLoadMoreComplete();

            super.onPostExecute(result);
        }

        @Override
        protected void onCancelled() {
            // Notify the loading more operation has finished
            lyt.onLoadMoreComplete();
        }
    }

}

sqlite数据加载的代码。（CustomerDS.java）

package com.load.more.list.data;

import java.util.ArrayList;

import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;

import com.load.more.list.model.Customer;

public class CustomerDS {

    private SQLiteDatabase fmcgDB;
    private DatabaseHelper dbHelper;
    Context context;

    public CustomerDS(Context context) {
        this.context = context;
        dbHelper = new DatabaseHelper(context);
    }

    public void open() throws SQLException {
        fmcgDB = dbHelper.getWritableDatabase();
    }

    public ArrayList<String> getAllCustomersFromTo(int limit, int offset) {
        if (fmcgDB == null) {
            open();
        } else if (!fmcgDB.isOpen()) {
            open();
        }
        ArrayList<String> customersList = new ArrayList<String>();

        String selectQuery = "SELECT * FROM " + dbHelper.TABLE_CUSTOMER
                + " LIMIT " + limit + " OFFSET " + offset +"";

        Cursor cursor = null;
        try{
            cursor = fmcgDB.rawQuery(selectQuery, null);

        while (cursor.moveToNext()) {
            customersList.add(cursor.getString((cursor.getColumnIndex(dbHelper.CUSTOMER_NAME))));

        }
        }
        finally {  
            if (cursor!=null) {
                cursor.close();
            }
            fmcgDB.close();
            return customersList;
            }
    }
}

LoadMoreListView使用sqlite数据库实现Fragment

1 个答案: