android - 如何将我的 Cursor 从我的数据库类导入到我当前的类中？

Question

这是我的数据库类的代码:

package one.two;

import java.util.List;

import android.app.ListActivity;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;

import java.util.ArrayList;

public class DBAdapter extends ListActivity
{
    public String status = "status";
    public String id = "id";
    public String arrival = "arrival";
    public String destination = "destination";
    public String ferry = "ferry";
    private static String DB_PATH = "/data/data/one.two/databases/";
    private static final String DATABASE_NAME = "ferry.db";
    private static final String DATABASE_TABLE = "port";
    public static Context context;
    public Cursor c;

    public static SQLiteDatabase DbLib;


    //overloaded non-null constructor
    public DBAdapter(Context context)
    {
        DbLib = context.openOrCreateDatabase(DATABASE_NAME,  SQLiteDatabase.CREATE_IF_NECESSARY,null);
        System.out.println("OpenOrCreateDB Done");
    }

    public class DatabaseHelper extends SQLiteOpenHelper
    {
        Context context;
        DatabaseHelper(Context context)
        {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
            this.context = context;

        }//end constructor DatabaseHelper

        // ---closes the database---
        public void close()
        {
            DBHelper.close();
        }//end close()

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion,
                int newVersion)
        {
        }//end onUpgrade()

        @Override
        public void onCreate(SQLiteDatabase db)
        {

        }//end onCreate()
    }// end class DatabaseHelper

    private static DatabaseHelper DBHelper;

    private static final int DATABASE_VERSION = 1;




        public static ArrayList<String> getAllTitles()
        {

            ArrayList<String> port = new ArrayList<String>();
                Cursor c=null;


                c = DbLib.query("port",
                        new String[] { "status", "id", "arrival",
                                "destination", "ferry" }, null, null,
                        null, null, null);
                try {
                    if (c!=null) { // start - when there is at least 1 record
                        System.out.println("Cursor is NOT NULL");

                        int i =0;
                        for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) 

                        {
                                    // Debug Stm
                            System.out.println("Record No. "+i);
                            System.out.println(c.getString(0));
                            System.out.println(c.getString(1));
                            System.out.println(c.getString(2));
                            System.out.println(c.getString(3));
                            System.out.println(c.getString(4));
                            // Assign database cursor.records to arraylist
                            port.add(i,c.getString(0));
                            port.add(i,c.getString(1));
                            port.add(i,c.getString(2));
                            port.add(i,c.getString(3));
                            port.add(i,c.getString(4));
                            i = i + 1;

                        }
                    } // end - where there is at least 1 record


                } finally {
                    if (c!=null) {
                    c.close();
                }

                }   
            return port;
        }//end getAllTitles()

        public void open() {
            //Open the database
            String myPath = DB_PATH + DATABASE_NAME;
            DbLib = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

        }
    }//end class DBAdapter

我的抵达舱

package one.two;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

import android.app.ListActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;

public class Arrival extends ListActivity
{
    private ListView listView;


    /** Called when the activity is first created. */
    public void onCreate(Bundle savedInstanceState)
    {
        ArrayList<String> retList = new ArrayList<String>();

        System.out.println("Start onCreate Function\n");

        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        System.out.println("In onCreate Function\n");
        System.out.println("In of GetData\n");
        DBAdapter db = new DBAdapter(this); 

        System.out.println("DB Open\n");
        db.open();
        System.out.println("DB Opened\n");
        retList = getData();
        System.out.println("Out of GetData\n");
        // force count no. of records in table
        // dump to check index
        int cnt = 2;

        int i=0;
        for (i = 0; i<cnt; i++)
            System.out.println(retList.toString());


        listView = (ListView) findViewById(android.R.id.list);
        SimpleCursorAdapter mAdapter = new SimpleCursorAdapter(this, android.R.id.list, null, null, null);
        this.setListAdapter(mAdapter);
        // db.close();
    }

    @SuppressWarnings("static-access")
    public static ArrayList<String> getData()
     {


        ArrayList<String> items = DBAdapter.getAllTitles();
        // titles ???? redundant
        //ArrayList<String> titles = new ArrayList<String>(items);
        System.out.println("Return a LIST titles\n");
         return items;
        }


    }

谢谢

Answer 1

我觉得您的 DBAdapter 正在扩展 ListActivity 很奇怪 - 您是这个意思吗？

同样要返回 Cursor，您需要在 DBAdapter 类中创建一个返回它的方法:

protected Cursor getCursor() {
    return c;
}

然后 Arrivals 将需要持有对 DBAdapter 类的引用并执行:

Cursor result = db.getCursor();