[Android] อยากทราบเกี่ยวกับการโหลด ListView ออกจากฐานข้อมูล กรณีข้อมูลมากๆ

package com.myapp;

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

import android.os.Bundle;
import android.app.Activity;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity  {
	
	ArrayList<HashMap<String, String>> MyArrList;
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       
        // listView1
        final ListView lisView1 = (ListView)findViewById(R.id.listView1); 
        	
		MyArrList = new ArrayList<HashMap<String, String>>();
		HashMap<String, String> map;
		
		/*** Rows 1 ***/
		map = new HashMap<String, String>();
		map.put("ID", "1");
		map.put("Code", "TH");
		map.put("Country", "Thailand");
		MyArrList.add(map);
		
		/*** Rows 2 ***/
		map = new HashMap<String, String>();
		map.put("ID", "2");
		map.put("Code", "VN");
		map.put("Country", "Vietnam");
		MyArrList.add(map);	
		
		/*** Rows 3 ***/
		map = new HashMap<String, String>();
		map.put("ID", "3");
		map.put("Code", "ID");
		map.put("Country", "Indonesia");
		MyArrList.add(map);	
		
		/*** Rows 4 ***/
		map = new HashMap<String, String>();
		map.put("ID", "4");
		map.put("Code", "LA");
		map.put("Country", "Laos");
		MyArrList.add(map);	
		
		/*** Rows 5 ***/
		map = new HashMap<String, String>();
		map.put("ID", "5");
		map.put("Code", "MY");
		map.put("Country", "Malaysia");
		MyArrList.add(map);		
       
		lisView1.setAdapter(new CountryAdapter(this));
		
    }
    
    public class CountryAdapter extends BaseAdapter 
    {
        private Context context;

        public CountryAdapter(Context c) 
        {
        	// TODO Auto-generated method stub
            context = c;
        }
 
        public int getCount() {
        	// TODO Auto-generated method stub
            return MyArrList.size();
        }

 
        public Object getItem(int position) {
        	// TODO Auto-generated method stub
            return position;
        }
 
        public long getItemId(int position) {
        	// TODO Auto-generated method stub
            return position;
        }

		public View getView(final int position, View convertView,
				ViewGroup parent) {
			// TODO Auto-generated method stub
			CountryHolder holder = null;

			if (convertView == null) {
				
				LayoutInflater inflater = (LayoutInflater) context
						.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
				 convertView = inflater.inflate(R.layout.activity_column, null);

				holder = new CountryHolder();
				holder.ID = (TextView) convertView.findViewById(R.id.ColID);
				holder.Code = (TextView) convertView.findViewById(R.id.ColCode);
				holder.Country = (TextView) convertView.findViewById(R.id.ColCountry);

				convertView.setTag(holder);
			} else {
				holder = (CountryHolder) convertView.getTag();
			}

	        holder.ID.setText(MyArrList.get(position).get("ID"));
	        holder.Code.setText(MyArrList.get(position).get("Code"));
	        holder.Country.setText(MyArrList.get(position).get("Country"));
	        
			return convertView;

		}

    }
    
	public class CountryHolder {
		TextView ID;
		TextView Code;
		TextView Country;
	}

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
    
}

		public View getView(final int position, View convertView,
				ViewGroup parent) {
			// TODO Auto-generated method stub
			CountryHolder holder = null;

			if (convertView == null) {
				
				LayoutInflater inflater = (LayoutInflater) context
						.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
				 convertView = inflater.inflate(R.layout.activity_column, null);

				holder = new CountryHolder();
				holder.ID = (TextView) convertView.findViewById(R.id.ColID);
				holder.Code = (TextView) convertView.findViewById(R.id.ColCode);
				holder.Country = (TextView) convertView.findViewById(R.id.ColCountry);

				convertView.setTag(holder);
			} else {
				holder = (CountryHolder) convertView.getTag();
			}

	        holder.ID.setText(MyArrList.get(position).get("ID"));
	        holder.Code.setText(MyArrList.get(position).get("Code"));
	        holder.Country.setText(MyArrList.get(position).get("Country"));
	        
			return convertView;

		}

    }
    
	public class CountryHolder {
		TextView ID;
		TextView Code;
		TextView Country;
	}

package com.test;

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

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

public class myDBClass extends SQLiteOpenHelper {
	

    // Database Version
    private static final int DATABASE_VERSION = 1;
 
    // Database Name
    private static final String DATABASE_NAME = "lexitron";
 
    // Table Name
    private static final String TABLE_MEMBER = "eng2th";

	public myDBClass(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		// Create Table Name
	    db.execSQL("CREATE TABLE " + TABLE_MEMBER + 
		          "(_id INTEGER PRIMARY KEY AUTOINCREMENT," +
		          " esearch TEXT," +
		          " eentry TEXT," +
		          " tentry TEXT," +
		          " ecat TEXT," +
		          " ethai TEXT," +
		          " esyn TEXT," +
		          " eant TEXT);");
	   
	    Log.d("CREATE TABLE","Create Table Successfully.");
	}
	

	// Select Data
	public String[] SelectData(String strID) {
		// TODO Auto-generated method stub
		
		 try {
			String arrData[] = null;	
			
			 SQLiteDatabase db;
			 db = this.getReadableDatabase(); // Read Data
				
			 Cursor cursor = db.query(TABLE_MEMBER, new String[] { "*" }, 
					 	"_id=?",
			            new String[] { String.valueOf(strID) }, null, null, null, null);
			 
			 	if(cursor != null)
			 	{
					if (cursor.moveToFirst()) {
						arrData = new String[cursor.getColumnCount()];
						arrData[1] = cursor.getString(1);
						arrData[2] = cursor.getString(2);
						arrData[3] = cursor.getString(3);
						arrData[4] = cursor.getString(4);
					    arrData[6] = cursor.getString(6);
						arrData[7] = cursor.getString(7);		
					}
			 	}
			 	cursor.close();
			 	db.close();
				return arrData;
				
		 } catch (Exception e) {
		    return null;
		 }

	}
	
	// Show All Data
	public ArrayList<HashMap<String, String>> SelectAllData() {
		// TODO Auto-generated method stub
		
		 try {
			
			 ArrayList<HashMap<String, String>> MyArrList = new ArrayList<HashMap<String, String>>();
			 HashMap<String, String> map;
			 
			 SQLiteDatabase db;
			 db = this.getReadableDatabase(); // Read Data
				
			 String strSQL = "SELECT  * FROM " + TABLE_MEMBER;
			 Cursor cursor = db.rawQuery(strSQL, null);
			 int i,j;	
			 if(cursor != null)
			 	{
				 for(i=1; i<=10; i++){
			 		if (cursor.moveToNext())
			 		{
			 			//do{
			 	        	map = new HashMap<String, String>();
			 	        	map.put("_id", cursor.getString(0));
				 	        map.put("esearch", cursor.getString(1));
				 	        map.put("ecat", "["+cursor.getString(4)+"]");
				 	        MyArrList.add(map);
			 			//} while(cursor.moveToNext());
			 				
						 	        }
			 	        }		 	    
			 	    }
			 	cursor.close();
			 	db.close();
				return MyArrList;
		 } catch (Exception e) {
			 Log.e("Exception", e.toString());
			 return null; 
		 }
	}
	
	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_MEMBER);
        
        // Re Create on method  onCreate
        onCreate(db);
	}

}

package com.test;

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

import android.app.Activity;
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.SimpleAdapter;

public class ShowActivity extends Activity  {
	
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_show);
	
		final myDBClass myDb = new myDBClass(this);
		final ArrayList<HashMap<String, String>> MebmerList = myDb.SelectAllData();   
		
        // listView1
        ListView lisView1 = (ListView)findViewById(R.id.listView1); 
        
        SimpleAdapter sAdap;
        sAdap = new SimpleAdapter(ShowActivity.this, MebmerList, R.layout.activity_column,
                new String[] {"esearch","ecat"}, new int[] {R.id.ColEsearch,R.id.ColEcat});      
        lisView1.setAdapter(sAdap);
        
        lisView1.setOnItemClickListener(new OnItemClickListener() {
		      public void onItemClick(AdapterView<?> myAdapter, View myView, int position, long mylng) {
		    	   
		    	  	// Show on new activity
	            	Intent newActivity = new Intent(ShowActivity.this,DetailActivity.class);
	            	newActivity.putExtra("ID", MebmerList.get(position).get("_id").toString());
	            	startActivity(newActivity);

		      }       
        });
		   
		
		// btnCancel (Cancel)
        final Button cancel = (Button) findViewById(R.id.btnCancel);
        cancel.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {        	
            	// Open Form Main
            	Intent newActivity = new Intent(ShowActivity.this,MainActivity.class);
            	startActivity(newActivity);
            }
        });
        
	}
	
    
}