Android App / JAVA

Two JAVA Data Files below (DAO & DatabaseHelper)

1. Inside the DAO constructor near line 35, add the code to initialze an instance of the database helper class.

DAO.java

package edu.csug.expenses.data; import java.util.HashMap; import android.content.ContentValues; import android.content.Context; import android.content.res.Resources; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteQueryBuilder; import android.text.TextUtils; import android.util.Log; /**  * Data Access Object supporting the Expenses Application  * @author Course 2771 Development Team  *  */ public class DAO { private static final String TAG="DAO"; private DatabaseHelper mDbHelper; /**  * A projection map used to select columns from the database  */  private static HashMap sExpensesProjectionMap; /*  * Static initializer block used to configure the projection map (column mappings)  */  static { // Creates a new projection map instance. The map returns a column name  // given a string. The two are usually equal.  sExpensesProjectionMap = new HashMap(); // Maps the string "_ID" to the column name "_ID"  sExpensesProjectionMap.put(Expense.ExpenseItem.COLUMN_NAME_ID, Expense.ExpenseItem.COLUMN_NAME_ID); sExpensesProjectionMap.put(Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION, Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION); sExpensesProjectionMap.put(Expense.ExpenseItem.COLUMN_NAME_AMOUNT, Expense.ExpenseItem.COLUMN_NAME_AMOUNT); sExpensesProjectionMap.put(Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE, Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE); } /**  * Normal constructor for the DAO  * @param context  */  public DAO(Context context) { mDbHelper = new DatabaseHelper(context); } /**  * Special constructor to support unit testing  * @param context  * @param testMode if true then an in-memory DB will be created which avoids breaking the real db  * during testing  */  protected DAO(Context context, boolean testMode) { if(testMode){ mDbHelper = new DatabaseHelper(context, testMode); } else { mDbHelper = new DatabaseHelper(context); } } /**  * Deletes expenses by the id of the expense  * @param id  * @return number of rows deleted - should be 1 for success  */  public int deleteExpensesById(long id) { String finalWhere = Expense.ExpenseItem.COLUMN_NAME_ID + // The ID column name  " = " + // test for equality  id; SQLiteDatabase db = mDbHelper.getWritableDatabase(); // Performs the delete.  int count = db.delete( Expense.ExpenseItem.TABLE_NAME, // The database table name.  finalWhere, // The final WHERE clause  null // The incoming where clause values.  ); return count; } /**  * Deletes expenses as specified by the where clause composed of where and whereArgs  * @param where where clause - if null, matches all rows  * @param whereArgs values for ? place holders in the where clause  * @return number of rows deleted  */  public int deleteExpenses(String where, String[] whereArgs) { // Opens the database object in "write" mode.  SQLiteDatabase db = mDbHelper.getWritableDatabase(); int count = db.delete( Expense.ExpenseItem.TABLE_NAME, // The database table name  where, // The incoming where clause column names  whereArgs // The incoming where clause values  ); // Returns the number of rows deleted.  return count; } /**  * Inserts an Expense item which is expressed in expenseValues  *  * @param expenseValues the values to populate the Expense item with. Any that are missing will  * be defaulted  * @return the id of the expense added. This is in fact the SQLite ROWID value  */  public long insertExpense(ContentValues expenseValues) { // If the incoming values map is not null, uses it for the new values.  if (expenseValues != null) { expenseValues = new ContentValues(expenseValues); } else { // Otherwise, create a new value map  expenseValues = new ContentValues(); } // Gets the current system time in milliseconds  Long now = Long.valueOf(System.currentTimeMillis()); // If the values map doesn't contain the expense date, sets the value to the current  // time.  if (expenseValues.containsKey(Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE) == false) { expenseValues.put(Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE, now); } // If the values map doesn't contain a description, sets the value to the default description.  if (expenseValues.containsKey(Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION) == false) { Resources r = Resources.getSystem(); expenseValues.put(Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION, r.getString(android.R.string.untitled)); } // If the values map doesn't contain note text, sets the amount to 0.0f.  if (expenseValues.containsKey(Expense.ExpenseItem.COLUMN_NAME_AMOUNT) == false) { expenseValues.put(Expense.ExpenseItem.COLUMN_NAME_AMOUNT, 0.0f); } // Opens the database object in "write" mode.  SQLiteDatabase db = mDbHelper.getWritableDatabase(); // Performs the insert and returns the ID of the new expense item.  long rowId = db.insert( Expense.ExpenseItem.TABLE_NAME, // The table to insert into.  Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION, // A hack, SQLite sets this column value to null  // if values is empty.  expenseValues // A map of column names, and the values to insert  // into the columns.  ); //Log.d(TAG, "Insert ROWID= " + rowId);  if(rowId < 0){ throw new SQLException("Failed to insert expense."); } return rowId; } /**  * Queries the database for a single expense item based on it's ID  * @param expenseId the ID of the expense item to return  * @param projection the columns to populate in the cursor  * @return a Cursor containing the data for the Expense item  */  public Cursor queryExpenseById(long expenseId, String[] projection) { // Constructs a new query builder and sets its table name  SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); qb.setTables(Expense.ExpenseItem.TABLE_NAME); qb.appendWhere(Expense.ExpenseItem.COLUMN_NAME_ID + // the name of the ID column  "=" + expenseId); return performQuery(qb, projection, null, null, null); } /**  * General query method for expenses. Allows where clause and sort order to be  * specified @see {@link android.database.sqlite.SQLiteQueryBuilder#query(SQLiteDatabase, String[], String, String[], String, String, String)}  * @param projection  * @param selection A filter declaring which rows to return  * @param selectionArgs You may include ?s in selection, which will be replaced by the values from selectionArgs  * @param sortOrder How to order the rows, formatted as an SQL ORDER BY  * @return  */  public Cursor queryExpenses(String[] projection, String selection, String[] selectionArgs, String sortOrder) { // Constructs a new query builder and sets its table name  SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); qb.setTables(Expense.ExpenseItem.TABLE_NAME); return performQuery(qb, projection, selection, selectionArgs, sortOrder); } /**  * Helper method to map public query methods onto the SQLQueryBuilder class methods  * @param qb  * @param projection  * @param selection  * @param selectionArgs  * @param sortOrder  * @return  */  private Cursor performQuery(SQLiteQueryBuilder qb, String[] projection, String selection, String[] selectionArgs, String sortOrder) { // Opens the database object in "read" mode, since no writes need to be done.  SQLiteDatabase db = mDbHelper.getReadableDatabase(); qb.setProjectionMap(sExpensesProjectionMap); String orderBy; // If no sort order is specified, uses the default  if (TextUtils.isEmpty(sortOrder)) { orderBy = Expense.ExpenseItem.DEFAULT_SORT_ORDER; } else { // otherwise, uses the incoming sort order  orderBy = sortOrder; } Log.i(TAG, "performQuery. Projection: " + projection); /*  * Performs the query. If no problems occur trying to read the database, then a Cursor  * object is returned; otherwise, the cursor variable contains null. If no records were  * selected, then the Cursor object is empty, and Cursor.getCount() returns 0.  */  Cursor c = qb.query( db, // The database to query  projection, // The columns to return from the query  selection, // The columns for the where clause  selectionArgs, // The values for the where clause  null, // don't group the rows  null, // don't filter by row groups  orderBy // The sort order  ); return c; } /**  * Updates the expense item specified by the expenseId parameter. If an ID parameter is also specified in the values  * parameter it will be ignored.  * @param expenseId  * @param values  * @return  */  public int updateExpenseById( long expenseId, ContentValues values) { // Opens the database object in "write" mode.  SQLiteDatabase db = mDbHelper.getWritableDatabase(); int count; String where = Expense.ExpenseItem.COLUMN_NAME_ID + // The ID column name  " = " + expenseId; // test for equality   // Does the update and returns the number of rows updated.  count = db.update( Expense.ExpenseItem.TABLE_NAME, // The database table name.  values, // A map of column names and new values to use.  where, // The final WHERE clause to use  // placeholders for whereArgs  null // The where clause column values to select on, or  // null if the values are in the where argument.  ); // Returns the number of rows updated.  return count; } /**  * Updates all of the expenses matching where and whereArgs with the values supplied.  * @param values  * @param where where clause - if null, matches all rows  * @param whereArgs values for ? place holders in the where clause  * @return  */  public int updateExpenses( ContentValues values, String where, String[] whereArgs) { // Opens the database object in "write" mode.  SQLiteDatabase db = mDbHelper.getWritableDatabase(); int count; // Does the update and returns the number of rows updated.  count = db.update( Expense.ExpenseItem.TABLE_NAME, // The database table name.  values, // A map of column names and new values to use.  where, // The where clause column names.  whereArgs // The where clause column values to select on.  ); return count; } /**  * Used by test classes to directly access the database helper  * @return a handle to the database helper object for the provider's data.  */   DatabaseHelper getDbHelperForTest() { return mDbHelper; } } 

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DatabaseHelper.java

package edu.csug.expenses.data; import android.content.ContentValues; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import java.util.Calendar; public class DatabaseHelper extends SQLiteOpenHelper { private boolean mTestMode = false; private static final String DATABASE_NAME = "expenses.db"; // Should this be qualified?   private static final int DATABASE_VERSION = 1; private static final String EXPENSES_TABLE_CREATE = "CREATE TABLE " + Expense.ExpenseItem.TABLE_NAME + " (" + Expense.ExpenseItem.COLUMN_NAME_ID + " INTEGER PRIMARY KEY," + Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION + " TEXT, " + Expense.ExpenseItem.COLUMN_NAME_AMOUNT + " REAL, " + Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE + " TEXT " + ");"; public DatabaseHelper(Context context) { // If the 2nd parameter is null then the database is held in memory -- this form creates a file backed database  super(context, DATABASE_NAME, null, DATABASE_VERSION); // TODO Auto-generated constructor stub  } /**  * Alternative constructor for test mode  * @param context  * @param testMode state of flag is irrelevant. The presence of the 2nd argument causes the in-memory db to be created  */  public DatabaseHelper(Context context, boolean testMode) { // If the 2nd parameter is null then the database is held in memory -- this form creates an in memory database  super(context, null, null, DATABASE_VERSION); mTestMode = testMode; // TODO Auto-generated constructor stub  } @Override public void onCreate(SQLiteDatabase db) { // TODO Auto-generated method stub  // NOTE: the db passed in here seems to be linked to the file system  // The exec does effect the database.  db.execSQL(EXPENSES_TABLE_CREATE); // For the purposes of the course, add some dummy data items into the database  if(!mTestMode){ // Don't populate the DB in test mode  Calendar cal = Calendar.getInstance(); cal.add(Calendar.DATE, -4); insertExpense(db, 1, "Samples Restaurant", 28.50, cal.getTimeInMillis() + ""); cal.add(Calendar.DATE, -1); insertExpense(db, 2, "Night in 6 star hotel", 22222.99, cal.getTimeInMillis() + ""); cal.add(Calendar.DATE, -1); insertExpense(db, 3, "Lunch at the Restaurant at the End of the Universe", 9991.99, cal.getTimeInMillis() + ""); cal.add(Calendar.DATE, -10); insertExpense(db, 4, "Travel to Restaurant at the End of the Universe", 132221.99, cal.getTimeInMillis() + ""); } } private void insertExpense(SQLiteDatabase db, long id, String description, double amount, String date) { ContentValues values = new ContentValues(); values.put(Expense.ExpenseItem.COLUMN_NAME_ID, id); values.put(Expense.ExpenseItem.COLUMN_NAME_DESCRIPTION, description); values.put(Expense.ExpenseItem.COLUMN_NAME_AMOUNT, amount); values.put(Expense.ExpenseItem.COLUMN_NAME_EXPENSE_DATE, date); db.insert(Expense.ExpenseItem.TABLE_NAME, null, values); } /**  * Not sure what to do with this. Could ignore for the course...  */  @Override public void onUpgrade(SQLiteDatabase db, int arg1, int arg2) { // TODO Auto-generated method stub   } }