Based upon your code I can see no issues.
- You may wish to try deleting the App's data, or uninstalling the App adding the line below (or adding the CommonSQLiteUtilities class and adding the two lines that have been added for testing below) and then rerunning the App (this would overcome any issue you may have had that resulted in the database being created but not any tables, in which case the
onCreate method would not run so any corrective changes (if any) may not have been applied).
Amending the CatalogActivity by adding the line :-
displayDatabaseInfo();
Results in the EditText being updated as expected (shows 0 rows in pets database).
If the underlying table didn't exist then if you added the line above, you'd experience an exception along the lines of :-
07-17 01:28:51.001 1321-1321/pets.pets E/AndroidRuntime: FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{pets.pets/pets.pets.CatalogActivity}: android.database.sqlite.SQLiteException: no such table: notatable (code 1): , while compiling: SELECT * FROM notatable
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Caused by: android.database.sqlite.SQLiteException: no such table: notatable (code 1): , while compiling: SELECT * FROM notatable
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:882)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:493)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37)
at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44)
at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1314)
at android.database.sqlite.SQLiteDatabase.rawQuery(SQLiteDatabase.java:1253)
at pets.pets.CatalogActivity.displayDatabaseInfo(CatalogActivity.java:40)
at pets.pets.CatalogActivity.onCreate(CatalogActivity.java:22)
at android.app.Activity.performCreate(Activity.java:5008)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
at android.app.ActivityThread.access$600(ActivityThread.java:130)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:137)
at android.app.ActivityThread.main(ActivityThread.java:4745)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
at dalvik.system.NativeStart.main(Native Method)
Note forced by changing the table name to notatable i.e.
Cursor cursor = db.rawQuery("SELECT * FROM " + "notatable", null);
Adding the CommonSQLiteUtilities class from Are there any methods that assist with resolving common SQLite issues?
and then adding the line :-
CommonSQLiteUtilities.logDatabaseInfo(mDbHelper.getWritableDatabase());
results in the log containing :-
07-17 01:36:51.191 1399-1399/? D/SQLITE_CSU: DatabaseList Row 1 Name=main File=/data/data/pets.pets/databases/shelter.db
Database Version = 1
Table Name = android_metadata Created Using = CREATE TABLE android_metadata (locale TEXT)
Table = android_metadata ColumnName = locale ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table Name = pets Created Using = CREATE TABLE pets (_id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT NOT NULL, breed TEXT, gender INTEGER NOT NULL, weight INTEGER NOT NULL DEFAULT 0)
Table = pets ColumnName = _id ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 1
Table = pets ColumnName = name ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table = pets ColumnName = breed ColumnType = TEXT Default Value = null PRIMARY KEY SEQUENCE = 0
Table = pets ColumnName = gender ColumnType = INTEGER Default Value = null PRIMARY KEY SEQUENCE = 0
Table = pets ColumnName = weight ColumnType = INTEGER Default Value = 0 PRIMARY KEY SEQUENCE = 0
Table Name = sqlite_sequence Created Using = CREATE TABLE sqlite_sequence(name,seq)
Table = sqlite_sequence ColumnName = name ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0
Table = sqlite_sequence ColumnName = seq ColumnType = Default Value = null PRIMARY KEY SEQUENCE = 0
Further confirming that the table is created.
The testing above was done using the following code :-
CatalogActivity.java
public class CatalogActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_catalog);
//displayDatabaseInfo();
PetDbHelper mDbHelper = new PetDbHelper(this);
SQLiteDatabase db = mDbHelper.getReadableDatabase();
displayDatabaseInfo();
CommonSQLiteUtilities.logDatabaseInfo(mDbHelper.getWritableDatabase());
}
/**
* Temporary helper method to display information in the onscreen TextView about the state of
* the pets database.
*/
private void displayDatabaseInfo() {
// To access our database, we instantiate our subclass of SQLiteOpenHelper
// and pass the context, which is the current activity.
PetDbHelper mDbHelper = new PetDbHelper(this);
// Create and/or open a database to read from it
SQLiteDatabase db = mDbHelper.getReadableDatabase();
// Perform this raw SQL query "SELECT * FROM pets"
// to get a Cursor that contains all rows from the pets table.
Cursor cursor = db.rawQuery("SELECT * FROM " + PetContract.PetEntry.TABLE_NAME, null);
try {
// Display the number of rows in the Cursor (which reflects the number of rows in the
// pets table in the database).
TextView displayView = (TextView) findViewById(R.id.text_view_pet);
displayView.setText("Number of rows in pets database table: " + cursor.getCount());
} finally {
// Always close the cursor when you're done reading from it. This releases all its
// resources and makes it invalid.
cursor.close();
}
}
}
PetDbHelper.java
public class PetDbHelper extends SQLiteOpenHelper {
public static final String LOG_TAG = PetDbHelper.class.getSimpleName();
/**
* Name of the database file
*/
private static final String DATABASE_NAME = "shelter.db";
/**
* Database version. If you change the database schema, you must increment the database version.
*/
private static final int DATABASE_VERSION = 1;
/**
* Constructs a new instance of {@link PetDbHelper}.
*
* @param context of the app
*/
public PetDbHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
/**
* This is called when the database is created for the first time.
*/
@Override
public void onCreate(SQLiteDatabase db) {
// Create a String that contains the SQL statement to create the pets table
String SQL_CREATE_PETS_TABLE = "CREATE TABLE " + PetContract.PetEntry.TABLE_NAME + " ("
+ PetContract.PetEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, "
+ PetContract.PetEntry.COLUMN_PET_NAME + " TEXT NOT NULL, "
+ PetContract.PetEntry.COLUMN_PET_BREED + " TEXT, "
+ PetContract.PetEntry.COLUMN_PET_GENDER + " INTEGER NOT NULL, "
+ PetContract.PetEntry.COLUMN_PET_WEIGHT + " INTEGER NOT NULL DEFAULT 0);";
// Execute the SQL statement
db.execSQL(SQL_CREATE_PETS_TABLE);
}
/**
* This is called when the database needs to be upgraded.
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// The database is still at version 1, so there's nothing to do be done here.
}
}
PetContract.java
public final class PetContract {
private PetContract() {}
public static final class PetEntry implements BaseColumns {
public static final String TABLE_NAME = "pets";
public static final String _ID = BaseColumns._ID;
public static final String COLUMN_PET_NAME = "name";
public static final String COLUMN_PET_BREED = "breed";
public static final String COLUMN_PET_GENDER = "gender";
public static final String COLUMN_PET_WEIGHT = "weight";
/* Possible values for gender. */
public static final int GENDER_UNKNOWN = 0;
public static final int GENDER_MALE = 1;
public static final int GENDER_FEMALE = 2;
}
}
CommonSQLiteUtilities.java
public class CommonSQLiteUtilities {
public static final boolean ERROR_CHECKING_ON = true;
public static final boolean ERROR_CHECKING_OFF = false;
// SQLite MASTER TABLE definitions
static final String SQLITE_MASTER = "sqlite_master";
static final String SM_TABLE_TYPE_COLUMN = "type";
static final String SM_NAME_COLUMN = "name";
static final String SM_TABLENAME_COLUMN = "tbl_name";
static final String SM_ROOTPAGE_COLUMN = "rootpage";
static final String SM_SQL_COLUMN = "sql";
static final String SM_TYPE_TABLE = "table";
static final String SM_TYPE_INDEX = "index";
static final String PRAGMA_STATEMENT = "PRAGMA ";
static final String PRAGMA_DATABASELIST = "database_list";
static final String PRAGMA_USERVERSION = "user_version";
static final String PRAGMA_ENCODING = "encoding";
static final String PRAGMA_FOREIGNKEYLIST = "foreign_key_list";
static final String PRAGMA_INDEXINFO = "index_info";
static final String PRAGMA_INDEXLIST = "index_list";
static final String PRAGMA_TABLEINFO = "table_info";
static final String PRAGMA_DBLIST_SEQ_COL = "seq";
static final String PRAGMA_DBLIST_NAME_COL = "name";
static final String PRAGMA_DBLIST_FILE_COL = "file";
static final String PRAGMA_TABLEINFO_CID_COL = "cid";
static final String PRAGMA_TABLEINFO_NAME_COl = "name";
static final String PRAGMA_TABLEINFO_TYPE_COL = "type";
static final String PRAGMA_TABLEINFO_NOTNULL_COL = "notnull";
static final String PRAGMA_TABLEINFO_DEFAULTVALUE_COL = "dflt_value";
static final String PRAGMA_TABLEINFO_PRIMARYKEY_COL = "pk";
static final String CSU_TAG = "SQLITE_CSU";
private CommonSQLiteUtilities() {}
/**
* Write Database information to the log;
* Information wrttien is:
* the database path, (will/should show connected databases)
* the version number (note! user version i.e. version coded in DBHelper),
* the tables in the database (includes android_metadata but not sqlite_master),
* the columns of the tables
* @param db The SQLite database to be interrogated
*/
public static void logDatabaseInfo(SQLiteDatabase db) {
// Issue PRAGMA database_list commnand
Cursor dblcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_DATABASELIST,null);
// Write databases to the log
while (dblcsr.moveToNext()) {
Log.d(CSU_TAG,"DatabaseList Row " + Integer.toString(dblcsr.getPosition() + 1) +
" Name=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_NAME_COL)) +
" File=" + dblcsr.getString(dblcsr.getColumnIndex(PRAGMA_DBLIST_FILE_COL))
);
}
dblcsr.close();
// Issue PRAGMA user_version to get the version and write to the log
//Note! to set user_version use execSQL not rawQuery
Cursor uvcsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_USERVERSION,null);
while (uvcsr.moveToNext()) {
Log.d(CSU_TAG,"Database Version = " +
Integer.toString(uvcsr.getInt(uvcsr.getColumnIndex(PRAGMA_USERVERSION))));
}
uvcsr.close();
// Select all table entry rows from sqlite_master
Cursor tlcsr = db.rawQuery("SELECT * FROM " +
SQLITE_MASTER + " WHERE " +
SM_TABLE_TYPE_COLUMN + "='" + SM_TYPE_TABLE + "'"
,null);
// For each table write table information to the log
// (inner loop gets column info per table)
while (tlcsr.moveToNext()) {
String current_table = tlcsr.getString(tlcsr.getColumnIndex(SM_TABLENAME_COLUMN));
Log.d(CSU_TAG,
"Table Name = " + current_table +
" Created Using = " + tlcsr.getString(tlcsr.getColumnIndex(SM_SQL_COLUMN)),
null
);
// Issue PRAGMA tabel_info for the current table
Cursor ticsr = db.rawQuery(PRAGMA_STATEMENT + PRAGMA_TABLEINFO +
"(" + current_table + ")",
null
);
// Write column info (see headings below) to the log
while (ticsr.moveToNext()) {
Log.d(CSU_TAG,"Table = " +
current_table +
" ColumnName = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_NAME_COl)) +
" ColumnType = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_TYPE_COL)) +
" Default Value = " +
ticsr.getString(ticsr.getColumnIndex(PRAGMA_TABLEINFO_DEFAULTVALUE_COL)) +
" PRIMARY KEY SEQUENCE = " + Integer.toString(
ticsr.getInt(ticsr.getColumnIndex(PRAGMA_TABLEINFO_PRIMARYKEY_COL))
)
);
}
ticsr.close();
}
tlcsr.close();
}
/**
* Generic get all rows from an SQlite table,
* allowing the existence of the table to be checked and also
* allowing the ROWID to be added AS a supplied string
*
* @param db The SQLiteDatabase
* @param tablename The name of the table from which the
* returned cursor will be created from;
* Note!
* @param use_error_checking Whether ot not to try to detect errors
* currently just table doesn't exist,
* true to turn on, false to turn off
* ERROR_CHECKING_ON = true
* ERROR_CHECKING_OFF = false
* @param forceRowidAs If length of string passed is 1 or greater
* then a column, as an alias of ROWID, will be
* added to the cursor
* @return the extracted cursor, or in the case of the
* underlying table not existing an empty cursor
* with no columns
*/
public static Cursor getAllRowsFromTable(SQLiteDatabase db,
String tablename,
boolean use_error_checking,
String forceRowidAs) {
String[] columns = null;
// Tablename must be at least 1 character in length
if (tablename.length() < 1) {
Log.d(CSU_TAG,new Object(){}.getClass().getEnclosingMethod().getName() +
" is finishing as the provided tablename is less than 1 character in length"
);
return new MatrixCursor(new String[]{});
}
// If use_error_checking is true then check that the table exists
// in the sqlite_master table
if (use_error_checking) {
Cursor chkcsr = db.query(SQLITE_MASTER,null,
SM_TABLE_TYPE_COLUMN + "=? AND "
+ SM_TABLENAME_COLUMN + "=?",
new String[]{SM_TYPE_TABLE,tablename},
null,null,null
);
// Ooops table is not in the Database so return an empty
// column-less cursor
if (chkcsr.getCount() < 1) {
Log.d(CSU_TAG,"Table " + tablename +
" was not located in the SQLite Database Master Table."
);
// return empty cursor with no columns
return new MatrixCursor(new String[]{});
}
chkcsr.close();
}
// If forcing an alias of ROWID then user ROWID AS ???, *
if(forceRowidAs != null && forceRowidAs.length() > 0) {
columns = new String[]{"rowid AS " +forceRowidAs,"*"};
}
// Finally return the Cursor but trap any exceptions
try {
return db.query(tablename, columns, null, null, null, null, null);
} catch (Exception e) {
Log.d(CSU_TAG,"Exception encountered but trapped when querying table " + tablename +
" Message was: \n" + e.getMessage());
Log.d(CSU_TAG,"Stacktrace was:");
e.printStackTrace();
return new MatrixCursor(new String[]{});
}
}
/**
* Create and return a Cursor devoid of any rows and columns
* Not used, prehaps of very little use.
* @param db The Sqlite database in which the cursor is to be created
* @return The empty Cursor
*/
private static Cursor getEmptyColumnLessCursor(SQLiteDatabase db) {
return new MatrixCursor(new String[]{});
}
/**
* Write column names in the passed Cursor to the log
* @param csr The Cursor to be inspected.
*/
public static void logCursorColumns(Cursor csr) {
Log.d(CSU_TAG,
new Object(){}.getClass().getEnclosingMethod().getName() +
" invoked. Cursor has the following " +
Integer.toString(csr.getColumnCount())+
" columns.");
int position = 0;
for (String column: csr.getColumnNames()) {
position++;
Log.d(CSU_TAG,"Column Name " +
Integer.toString(position) +
" is "
+ column
);
}
}
/**
* Write the contents of the Cursor to the log
* @param csr The Cursor that is to be displayed in the log
*/
public static void logCursorData(Cursor csr) {
int columncount = csr.getColumnCount();
int rowcount = csr.getCount();
int csrpos = csr.getPosition(); //<<< added 20171016
Log.d(CSU_TAG,
new Object(){}.getClass().getEnclosingMethod().getName() +
" Cursor has " +
Integer.toString(rowcount) +
" rows with " +
Integer.toString(columncount) + " columns."
);
csr.moveToPosition(-1); //Ensure that all rows are retrieved <<< added 20171016
while (csr.moveToNext()) {
String unobtainable = "unobtainable!";
String logstr = "Information for row " + Integer.toString(csr.getPosition() + 1) + " offset=" + Integer.toString(csr.getPosition());
for (int i=0; i < columncount;i++) {
logstr = logstr + "\n\tFor Column " + csr.getColumnName(i);
switch (csr.getType(i)) {
case Cursor.FIELD_TYPE_NULL:
logstr = logstr + " Type is NULL";
break;
case Cursor.FIELD_TYPE_FLOAT:
logstr = logstr + "Type is FLOAT";
break;
case Cursor.FIELD_TYPE_INTEGER:
logstr = logstr + " Type is INTEGER";
break;
case Cursor.FIELD_TYPE_STRING:
logstr = logstr + " Type is STRING";
break;
case Cursor.FIELD_TYPE_BLOB:
logstr = logstr + " Type is BLOB";
break;
}
String strval_log = " value as String is ";
String lngval_log = " value as long is ";
String dblval_log = " value as double is ";
String blbval_log = "";
try {
strval_log = strval_log + csr.getString(i);
lngval_log = lngval_log + csr.getLong(i);
dblval_log = dblval_log + csr.getDouble(i);
} catch (Exception e) {
strval_log = strval_log + unobtainable;
lngval_log = lngval_log + unobtainable;
dblval_log = dblval_log + unobtainable;
try {
blbval_log = " value as blob is " +
getBytedata(csr.getBlob(i),24);
} catch (Exception e2) {
e2.printStackTrace();
}
}
logstr = logstr + strval_log + lngval_log + dblval_log + blbval_log;
}
Log.d(CSU_TAG,logstr);
}
csr.moveToPosition(csrpos); // restore cursor position <<< added 20171016
}
/**
* Return a hex string of the given byte array
* @param bytes The byte array to be converted to a hexadecimal string
* @param limit the maximum number of bytes;
* note returned string will be up to twice as long
* @return The byte array represented as a hexadecimal string
*/
private static String getBytedata(byte[] bytes, int limit) {
if (bytes.length < limit) {
return convertBytesToHex(bytes);
} else {
byte[] subset = new byte[limit];
System.arraycopy(bytes,0,subset,0,limit);
return convertBytesToHex(subset);
}
}
// HEX characters as a char array for use by convertBytesToHex
private final static char[] hexarray = "0123456789ABCDEF".toCharArray();
/**
* Return a hexadecimal string representation of the passed byte array
* @param bytes The byte array to be represented.
* @return The string representing the byte array as hexadecimal
*/
private static String convertBytesToHex(byte[] bytes) {
char[] hexstr = new char[bytes.length * 2];
for (int i=0; i < bytes.length; i++) {
int h = bytes[i] & 0xFF;
hexstr[i * 2] = hexarray[h >>> 4];
hexstr[i * 2 + 1] = hexarray[h & 0xF];
}
return new String(hexstr);
}
}
activity_catalog.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".CatalogActivity">
<TextView
android:id="@+id/text_view_pet"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hello World!"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</android.support.constraint.ConstraintLayout>
