我正在尝试从我的 SQLite DB 中提取数据并将其显示在列表视图中，这是我目前所拥有的，但它只将第一条记录放在列表视图中。我认为“while (mCursor.moveToNext()){”位需要更改，但不确定如何更改。原始代码每次将每条记录放在一个新行的文本视图中。
if (mCursor == null){
mCursor.close();
Log.w("cursor", "null cursor");
}
mCursor.moveToFirst();
String[] s = null;
while (mCursor.moveToNext()){
s = new String[] { foodNameColumn, proteinColumn, fatColumn, carbsColumn };
mCursor.moveToNext();
}
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.aa_four_column,
mCursor,
s,
new int[] { R.id.txtCol1, R.id.txtCol2, R.id.txtCol3, R.id.txtCol4 }, 0);
lvDB.setAdapter(adapter);
更新：
我已经改变了它，所以只有这个代码在 onCreate 方法中，但同样的事情发生了，当数据库中有多个东西时显示一个项目。
mCursor = dataBase.select("SELECT * FROM " + TABLE_NAME);
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.aa_four_column,
mCursor,
new String[] { foodNameColumn, proteinColumn, fatColumn, carbsColumn },
new int[] { R.id.txtCol1, R.id.txtCol2, R.id.txtCol3, R.id.txtCol4 }, 0);
lvDB.setAdapter(adapter);
aa_column_four.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:id="@+id/txtCol1"
android:layout_width="181dp"
android:layout_height="wrap_content"
android:text="Column 1 text will end up here!" />
<TextView
android:id="@+id/txtCol2"
android:layout_width="63dp"
android:layout_height="wrap_content"
android:text="Column 2 text will end up here!" />
<TextView
android:id="@+id/txtCol3"
android:layout_width="96dp"
android:layout_height="wrap_content"
android:text="Column 3 text will end up here!" />
<TextView
android:id="@+id/txtCol4"
android:layout_width="104dp"
android:layout_height="wrap_content"
android:text="Column 4 text will end up here!" />
</LinearLayout>
数据库管理器类
public class DataBaseManager extends SQLiteOpenHelper {
//the MAIN package of your project
private static String DB_PATH = "/data/data/com.example.activities/databases/";
//the name of your database
private static String DB_NAME = "DB_Nutrition";
private static SQLiteDatabase mDataBase;
private static DataBaseManager sInstance = null;
// database version
private static final int DATABASE_VERSION = 1;
/**
* Constructor Takes and keeps a reference of the passed context in order to
* access to the application assets and resources.
*/
DataBaseManager() {
super(ApplicationContextProvider.getContext(), DB_NAME, null, DATABASE_VERSION);
try {
createDataBase();
openDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
/**
* Singleton for DataBase
*
* @return singleton instance
*/
public static DataBaseManager instance() {
if (sInstance == null) {
sInstance = new DataBaseManager();
}
return sInstance;
}
/**
* Creates a empty database on the system and rewrites it with your own
* database.
*
* @throws java.io.IOException io exception
*/
private void createDataBase() throws IOException {
boolean dbExist = checkDataBase();
if (dbExist) {
// do nothing - database already exist
} else {
// By calling this method an 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 doesn't exist yet.
}
if (checkDB != null) {
checkDB.close();
}
return checkDB != null;
}
/**
* 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.
*
* @throws java.io.IOException io exception
*/
public void copyDataBase() throws IOException {
// Open your local db as the input stream
InputStream myInput = ApplicationContextProvider.getContext().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();
}
private void openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
mDataBase = SQLiteDatabase.openDatabase(myPath, null,
SQLiteDatabase.OPEN_READWRITE);
}
/**
* Select method
*
* @param query select query
* @return - Cursor with the results
* @throws android.database.SQLException sql exception
*/
public Cursor select(String query) throws SQLException {
return mDataBase.rawQuery(query, null);
}
/**
* Insert method
*
* @param table - name of the table
* @param values values to insert
* @throws android.database.SQLException sql exception
*/
public void insert(String table, ContentValues values) throws SQLException {
mDataBase.insert(table, null, values);
}
/**
* Delete method
*
* @param table - table name
* @param where WHERE clause, if pass null, all the rows will be deleted
* @throws android.database.SQLException sql exception
*/
public void delete(String table, String where) throws SQLException {
mDataBase.delete(table, where, null);
}
/**
* Update method
*
* @param table - table name
* @param values - values to update
* @param where - WHERE clause, if pass null, all rows will be updated
*/
public void update(String table, ContentValues values, String where) {
mDataBase.update(table, values, where, null);
}
/**
* Let you make a raw query
*
* @param command - the sql comand you want to run
*/
public void sqlCommand(String command) {
mDataBase.execSQL(command);
}
@Override
public synchronized void close() {
if (mDataBase != null)
mDataBase.close();
super.close();
}
@Override
public void onCreate(SQLiteDatabase db) {
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
错误
03-03 15:42:13.894: E/SQLiteLog(9809): (14) cannot open file at line 30176 of [00bb9c9ce4]
03-03 15:42:13.894: E/SQLiteLog(9809): (14) os_unix.c:30176: (2) open(/data/data/com.example.activities/databases/DB_Nutrition) -
03-03 15:42:13.904: E/SQLiteDatabase(9809): Failed to open database '/data/data/com.example.activities/databases/DB_Nutrition'.
03-03 15:42:13.904: E/SQLiteDatabase(9809): android.database.sqlite.SQLiteCantOpenDatabaseException: unknown error (code 14): Could not open database
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnection.nativeOpen(Native Method)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:209)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnection.open(SQLiteConnection.java:193)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnectionPool.openConnectionLocked(SQLiteConnectionPool.java:463)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:185)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteConnectionPool.open(SQLiteConnectionPool.java:177)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteDatabase.openInner(SQLiteDatabase.java:804)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteDatabase.open(SQLiteDatabase.java:789)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:694)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.database.sqlite.SQLiteDatabase.openDatabase(SQLiteDatabase.java:669)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.example.db_food.DataBaseManager.checkDataBase(DataBaseManager.java:228)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.example.db_food.DataBaseManager.createDataBase(DataBaseManager.java:193)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.example.db_food.DataBaseManager.<init>(DataBaseManager.java:163)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.example.db_food.DataBaseManager.instance(DataBaseManager.java:179)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.example.db_food.MyActivity.onCreate(MyActivity.java:63)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.Activity.performCreate(Activity.java:5104)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.os.Handler.dispatchMessage(Handler.java:99)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.os.Looper.loop(Looper.java:137)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at android.app.ActivityThread.main(ActivityThread.java:5041)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at java.lang.reflect.Method.invokeNative(Native Method)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at java.lang.reflect.Method.invoke(Method.java:511)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-03 15:42:13.904: E/SQLiteDatabase(9809): at dalvik.system.NativeStart.main(Native Method)