為了讓user對AP所做的變更能保留下來, 本範例加入SQLite來儲存資料.
開始先建立一個資料表"l_listData",其欄位有兩個: "l_id", "l_data", 代表資料ID與資料字串.
ID是資料庫中自動增加的整數, 讓我們用cursor篩選時可由l_id找到該筆資料並做處理.
得到傳回資料表的資料筆數：cursor.getCount()
得到資料表第index欄的欄名：cursor.getColumnName(0)
得到欄名為name的index：cursor.getColumnIndex("name")
ListView_malloc_SQLite.java
package com.tsots.ListView_malloc_SQLite;
import java.util.ArrayList;
import java.util.List;
import android.app.Activity;
import android.content.Context;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
public class ListView_malloc_SQLite extends Activity
{
String tables[] = {"l_listData"};
String[] updateFields =
{
"l_data"
};
String fieldNames[][] =
{
{ "l_id", "l_data"}
};
String fieldTypes[][] =
{
{ "INTEGER PRIMARY KEY AUTOINCREMENT", "text"}
};
int version = 1;
private MySQLiteOpenHelper dbHelper = new MySQLiteOpenHelper (
this,
"SQLite_LsitView.db",
null,
version, /*version*/
tables,
fieldNames,
fieldTypes
);
Context context = ListView_malloc_SQLite.this;
String tag = "ListView_malloc_SQLite.this";
String[] countriesStr;
TextView myTextView;
EditText myEditText;
Button myButton_add;
Button myButton_remove;
ListView listview;
ArrayAdapter adapter2;
List allData;
List allId;
String newData;
int click_id;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
myTextView = (TextView) findViewById(R.id.myTextView);
myEditText = (EditText) findViewById(R.id.myEditText);
myButton_add = (Button) findViewById(R.id.myButton_add);
myButton_remove = (Button) findViewById(R.id.myButton_remove);
listview = (ListView) findViewById(R.id.listview1);
countriesStr = getResources().getStringArray(R.array.array_listview);
default_sqlite_data();
load_sqlite_data();
listview.setOnItemClickListener(new ListView.OnItemClickListener()
{
public void onItemClick(AdapterView arg0, View arg1, int id, long arg3)
{
myTextView.setText(allData.get(id));
myEditText.setText(allData.get(id));
click_id = id;
System.out.println("select: "+ arg3);
}
});
myButton_add.setOnClickListener(new Button.OnClickListener()
{
public void onClick(View arg0)
{
newData = myEditText.getText().toString();
for (int i = 0; i < adapter2.getCount(); i++)
{
//若此筆資料已存在列表中, 則不加入
if (newData.equals(adapter2.getItem(i)))
{
return;
}
}
if (!newData.equals(""))
{
//寫入資料庫
String[] updateFields = {"l_data"};
String[] updateValues = {newData};
dbHelper.insert(tables[0], updateFields, updateValues);
//重新讀取一次資料庫
load_sqlite_data();
int position = adapter2.getPosition(newData);
listview.setSelection(position);
myEditText.setText("");
Log.i(tag, "add a new data: "+newData);
}
}
});
myButton_remove.setOnClickListener(new Button.OnClickListener()
{
public void onClick(View arg0)
{
if (myEditText.getText().toString() != "")
{
//從資料庫刪除
String where = "l_id=?";
String[] whereValue = {allId.get(click_id)};
dbHelper.delete(tables[0], where, whereValue);
//重新讀取一次資料庫
load_sqlite_data();
myEditText.setText("");
if (adapter2.getCount() == 0)
{
myTextView.setText("");
}
Log.i(tag, "delete a data: "+allData.get(click_id)+" from SQLite");
}
}
});
}
public void default_sqlite_data()
{
Cursor cursor1 = null;
try
{
cursor1 = dbHelper.select(tables[0], null, null, null, null, null, null);
System.out.println("cursor1.getCount() = "+cursor1.getCount());
if(cursor1.getCount() == 0)
{
String[] updateFields2 = {"l_data"};
cursor1.moveToFirst();
System.out.println("total data = "+countriesStr.length);
for(int i=0 ; i();
allId = new ArrayList();
while (cursor_listdata.moveToNext())
{
allId.add(cursor_listdata.getString(0));
allData.add(cursor_listdata.getString(1));
}
adapter2 = new ArrayAdapter(this,android.R.layout.simple_list_item_1, allData);
listview.setAdapter(adapter2);
}
catch(Exception e)
{
Log.e(tag, e.toString());
}
finally
{
cursor_listdata.close();
}
}
}//
select(): 查詢資料表
insert(): 新增一筆資料
delete(): 刪除一筆資料
update(): 更新資料表
MySQLiteOpenHelper.java
package com.tsots.ListView_malloc_SQLite;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
public class MySQLiteOpenHelper extends SQLiteOpenHelper
{
public String TableNames[];
public String FieldNames[][];
public String FieldTypes[][];
public static String NO_CREATE_TABLES = "no tables";
private String message = "";
public MySQLiteOpenHelper(Context context, String dbname, CursorFactory factory, int version, String tableNames[], String fieldNames[][], String fieldTypes[][])
{
super(context, dbname, factory, version);
TableNames = tableNames;
FieldNames = fieldNames;
FieldTypes = fieldTypes;
}
@Override
public void onCreate(SQLiteDatabase db)
{
if (TableNames == null)
{
message = NO_CREATE_TABLES;
return;
}
for (int i = 0; i < TableNames.length; i++)
{
String sql = "CREATE TABLE " + TableNames[i] + " (";
for (int j = 0; j < FieldNames[i].length; j++)
{
sql += FieldNames[i][j] + " " + FieldTypes[i][j] + ",";
}
sql = sql.substring(0, sql.length() - 1);
sql += ")";
db.execSQL(sql);
}
}
@Override
public void onUpgrade(SQLiteDatabase db, int arg1, int arg2)
{
for (int i = 0; i < TableNames[i].length(); i++)
{
String sql = "DROP TABLE IF EXISTS " + TableNames[i];
db.execSQL(sql);
}
onCreate(db);
}
public void execSQL(String sql) throws java.sql.SQLException
{
SQLiteDatabase db = this.getWritableDatabase();
db.execSQL(sql);
}
public Cursor select(String table, String[] columns, String selection, String[] selectionArgs, String groupBy, String having, String orderBy)
{
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy);
return cursor;
}
public long insert(String table, String fields[], String values[])
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
for (int i = 0; i < fields.length; i++)
{
cv.put(fields[i], values[i]);
}
return db.insert(table, null, cv);
}
public int delete(String table, String where, String[] whereValue)
{
SQLiteDatabase db = this.getWritableDatabase();
return db.delete(table, where, whereValue);
}
public int update(String table, String updateFields[],
String updateValues[], String where, String[] whereValue)
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues cv = new ContentValues();
for (int i = 0; i < updateFields.length; i++)
{
cv.put(updateFields[i], updateValues[i]);
}
return db.update(table, cv, where, whereValue);
}
public String getMessage()
{
return message;
}
@Override
public synchronized void close()
{
// TODO Auto-generated method stub
super.close();
}
}
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