Androidでsqliteデータベースからデータを取得し、TextViewで表示する方法
私はAndroidを学んでいます。問題があり、解決できません。既存のデータベースからデータを取得し、クリック後、TextViewに表示したい。
私のコードDataBaseHelperは次のようになります。
public class DataBaseHelper extends SQLiteOpenHelper {
//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/in.ekonomia.Android/databases/";
private static String DB_NAME = "cytaty";
private SQLiteDatabase myDataBase;
private final Context myContext;
/** * Constructor * Takes and keeps a reference of the passed context in order to access to the application assets and resources. * @param context */
public DataBaseHelper(Context context)
{
super(context, DB_NAME, null, 1);
this.myContext = context;
}
/** * Creates a empty database on the system and rewrites it with your own database. * */
public void createDataBase() throws IOException
{
boolean dbExist = checkDataBase();
if(dbExist){
//do nothing - database already exist
}else{
//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();
try
{
copyDataBase();
} catch (IOException e)
{
throw new Error("Error copying database");
}
}
}
/** * Check if the database already exist to avoid re-copying the file each time you open the application. * @return true if it exists, false if it doesn't */
private boolean checkDataBase()
{ SQLiteDatabase checkDB = null;
try
{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}catch (SQLiteException e)
{
//database does't exist yet.
}
if(checkDB != null)
{
checkDB.close();
}
return checkDB != null ? true : false;
}
/** * Copies your database from your local assets-folder to the just created empty database in the * system folder, from where it can be accessed and handled. * This is done by transfering bytestream. * */
private void copyDataBase() throws IOException
{
//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);
// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;
//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);
//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0)
{
myOutput.write(buffer, 0, length);
}
//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();
}
public void openDataBase() throws SQLException {
//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);
}
@Override
public synchronized void close()
{
if(myDataBase != null)
myDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db)
{ }
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { }
// Add your public helper methods to access and get content from the database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
// to you to create adapters for your views.
}
Cytaty.Javaは次のようになります。
package in.ekonomia.Android;
import Android.app.Activity;
import Android.os.Bundle;
import Android.view.View;
import Android.widget.Button;
public class cytaty extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.galeria);
Button bLosuj = (Button) findViewById(R.id.button1);
bLosuj.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
}
});
}
}
上記のようにしましたが、Eclipseでエラーが発生します。
Database name: cytaty
name of table: cytaty
columns: _id, autor, cytat
私のcodeは：
public void getData() {
public String[] getAppCategorydetail() {
String Table_Name="cytaty";
String selectQuery = "SELECT * FROM " + Table_Name;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
String[] data = null;
if (cursor.moveToFirst()) {
do {
// get the data into array,or class variable
} while (cursor.moveToNext());
}
db.close();
return data;
}
}
そして：
Button bLosuj = (Button) findViewById(R.id.button1);
bLosuj.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
DataBaseHelper myDataBaseHelper = new DataBaseHelper(cytaty.this);
myDataBaseHelper.openDataBase();
String text= myDataBaseHelper.getData();//this is the method to query
myDataBaseHelper.close();
// set text to your TextView
TextView tekst = (TextView) findViewById(R.id.editText1);
tekst.setText(text);
}
});
}
私は何を間違えていますか？データベースからデータを取得し、ボタンをクリックした後にTextViewに表示したい。あなたの助けに感謝します。
ボタンをクリックすると、最初にデータベースを開き、データを取得して、このようにデータベースを閉じます
_public class cytaty extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.galeria);
Button bLosuj = (Button) findViewById(R.id.button1);
bLosuj.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
myDatabaseHelper = new DatabaseHelper(cytaty.this);
myDatabaseHelper.openDataBase();
String text = myDatabaseHelper.getYourData(); //this is the method to query
myDatabaseHelper.close();
// set text to your TextView
}
});
}
}
_データベースクラスのgetYourData()は次のようになります
_public String[] getAppCategoryDetail() {
final String TABLE_NAME = "name of table";
String selectQuery = "SELECT * FROM " + TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
String[] data = null;
if (cursor.moveToFirst()) {
do {
// get the data into array, or class variable
} while (cursor.moveToNext());
}
cursor.close();
return data;
}
_TextView tekst = (TextView) findViewById(R.id.editText1);
EditTextをTextViewにキャストできません。
あなたは実際にこの次のコードを使用することができますが、それはラフですが、plzをチェックしてください
db = openOrCreateDatabase("sms.db", SQLiteDatabase.CREATE_IF_NECESSARY, null);
Cursor cc = db.rawQuery("SELECT * FROM datatable", null);
final ArrayList<String> row1 = new ArrayList<String>();
final ArrayList<String> row2 = new ArrayList<String>();
if(cc!=null) {
cc.moveToFirst();
startManagingCursor(cc);
for (int i=0; i<cc.getCount(); i++) {
String number = cc.getString(0);
String message = cc.getString(1);
row1.add(number);
row2.add(message);
final EditText et3 = (EditText) findViewById(R.id.editText3);
final EditText et4 = (EditText) findViewById(R.id.editText4);
Button bt1 = (Button) findViewById(R.id.button1);
bt1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case R.id.button1:
et3.setText(row1.get(count));
et4.setText(row2.get(count));
count++;
break;
default:
break;
}
}
});
cc.moveToNext();
}
まず、次のように編集テキストをキャストします。
TextView tekst = (TextView) findViewById(R.id.editText1);
tekst.setText(text);
そして、この行の前にないDBを閉じます...
myDataBaseHelper.close();