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我创建了一个使用android sqlite数据库的示例应用程序，我的要求是How can i use Sqlite database in my android activity?（请不要链接此链接）。我用下面的代码来做到这一点，如何从android sqlite数据库中获取选定的id值？
MainClass.java
public class MainClass extends Activity implements OnClickListener {
Button NUM_INPUT;
EditText enter_NUM;
int number;
DatabaseHandler db = new DatabaseHandler(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.sai_answers_home);
NUM_INPUT = (Button) findViewById(R.id.answerButton);
enter_NUM = (EditText) findViewById(R.id.saiAnssersEditText);
NUM_INPUT.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (v.getId() == R.id.answerButton) {
number = Integer.parseInt(this.enter_NUM.getText().toString());
// /System.out.println("EDITTEXTVALUE" + number);
Log.d("Reading: ", "Reading all contacts..");
List<Contact> contacts = db.getAllContacts(number);
for (Contact cn : contacts) {
String log = "Id: " + cn.getID() + " ,Name: " + cn.getName();
// Writing Contacts to log
Log.d("Name: ", log);
}
db.close();
}
}
}
DataBaseHandler.java
public class DatabaseHandler extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.sqlite.example/databases/";
private static String DB_NAME = "answers";
private SQLiteDatabase myDataBase;
private final Context myContext;
String myPath;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*
* @param context
*/
public DatabaseHandler(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 {
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
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.
public List<Contact> getAllContacts(int muNumber) {
List<Contact> contactList = new ArrayList<Contact>();
// Select All Query
String selectQuery = "SELECT * FROM ANSWER WHERE ID= " + muNumber;
System.out.println("QUERY STRING IS......>>>>>> " + selectQuery);
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
// looping through all rows and adding to list
if (cursor.moveToFirst()) {
do {
Contact contact = new Contact();
contact.setID(Integer.parseInt(cursor.getString(0)));
contact.setName(cursor.getString(1));
// contact.setPhoneNumber(cursor.getString(2));
// Adding contact to list
contactList.add(contact);
} while (cursor.moveToNext());
}
// return contact list
return contactList;
}
}
answers.db
当我执行此代码时出现错误，“android.database.sqlite.SQLiteException：no such table：ANSWER：，while compiling：SELECT * FROM ANSWER WHERE ID = 3”。我确切的要求是，当单击MainActivity类中的Button时，输入的值将传递到数据库。最后搜索数据库并返回数据库中的相应值。例如，我输入2并点击按钮，从数据库中我会得到“橙色”，我怎么能实现这一点。提前致谢。
我改变了它，但是会出现同样的错误 – Aerrow 2012-03-03 03:44:52
很奇怪，请尝试清理你的代码并重新执行，因为这是我能看到的唯一错误 – Android 2012-03-03 03:47:26