A very open question n00b-esque about expanding the Notepad tutorial on Android

Question

I want to start by asking for your collective patience ... I'm trying to learn how to program for Android by modifying a trial and error Google code Example code: Notepad Tutorial So far, everything has been very slow. (I also read Head First Java :)

My goal is to add an additional TextEdit field and a button to the training application ... I want the user to be able to enter text in the field, then click the button and the text they just entered is added to the database and then dropped to a text element in scrollView so that the recording of entries is visible to the viewer. Basically, my goal is to allow the user to add an unlimited amount of data (depending on the number of clicks on the button) in each database record. I got part of the way there (adding a new db field, creating a TextEdit and a button, etc.), but I can’t put it all together ... specifically, how to make it work at the end of db. I'm not sure I'm explaining this correctly ... but I will attach the appropriate source code to try to make it more clear.

(Note: KEY_HOUSE is the db field I added, and house / mHouseText are the corresponding variables)

NoteEdit.java

package com.android.demo.notepad3; import android.R.string; import android.app.Activity; import android.database.Cursor; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.CheckBox; import android.widget.EditText; import android.widget.TableLayout; import android.widget.TableRow; import android.widget.TextView; import android.widget.TableRow.LayoutParams; public class NoteEdit extends Activity{ private EditText mTitleText; private EditText mBodyText; private Long mRowId; private NotesDbAdapter mDbHelper; Button btn; int counter = 0; private EditText mHouseText; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); mDbHelper = new NotesDbAdapter(this); mDbHelper.open(); setContentView(R.layout.note_edit); setTitle(R.string.edit_note); mTitleText = (EditText) findViewById(R.id.title); mBodyText = (EditText) findViewById(R.id.body); mHouseText = (EditText) findViewById(R.id.house); Button confirmButton = (Button) findViewById(R.id.confirm); Button btn = (Button) findViewById(R.id.Button01); mRowId = (savedInstanceState == null) ? null : (Long) savedInstanceState.getSerializable(NotesDbAdapter.KEY_ROWID); if (mRowId == null) { Bundle extras = getIntent().getExtras(); mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID) : null; } populateFields(); confirmButton.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { setResult(RESULT_OK); finish(); } }); btn.setOnClickListener(new View.OnClickListener() { public void onClick(View view) { addrow(); } }); } private void populateFields() { if (mRowId != null) { Cursor note = mDbHelper.fetchNote(mRowId); startManagingCursor(note); mTitleText.setText(note.getString( note.getColumnIndexOrThrow(NotesDbAdapter.KEY_TITLE))); mBodyText.setText(note.getString( note.getColumnIndexOrThrow(NotesDbAdapter.KEY_BODY))); mHouseText.setText(note.getString( note.getColumnIndexOrThrow(NotesDbAdapter.KEY_HOUSE))); } } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); saveState(); outState.putSerializable(NotesDbAdapter.KEY_ROWID, mRowId); } @Override protected void onPause() { super.onPause(); saveState(); } @Override protected void onResume() { super.onResume(); populateFields(); } private void saveState() { String title = mTitleText.getText().toString(); String body = mBodyText.getText().toString(); String house = mHouseText.getText().toString(); if (mRowId == null) { long id = mDbHelper.createNote(title, body, house); if (id > 0) { mRowId = id; } } else { mDbHelper.updateNote(mRowId, title, body, house); } } private void addrow(){ //mHouseText = (EditText) findViewById(R.id.house); String house = mHouseText.getText().toString(); // get a reference for the TableLayout TableLayout table = (TableLayout) findViewById(R.id.TableLayout02); // create a new TableRow TableRow row = new TableRow(this); // create a new TextView TextView t = new TextView(this); // set the text to "text xx" t.setText(house); // create a CheckBox CheckBox c = new CheckBox(this); // add the TextView and the CheckBox to the new TableRow row.addView(t); row.addView(c); // add the TableRow to the TableLayout table.addView(row,new TableLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); } } 

NotesDbAdapter.java

 package com.android.demo.notepad3; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; * Simple notes database access helper class. Defines the basic CRUD operations * for the notepad example, and gives the ability to list all notes as well as * retrieve or modify a specific note. * * This has been improved from the first version of this tutorial through the * addition of better error handling and also using returning a Cursor instead * of using a collection of inner classes (which is less scalable and not * recommended). public class NotesDbAdapter { public static final String KEY_TITLE = "title"; public static final String KEY_BODY = "body"; public static final String KEY_HOUSE = "house"; public static final String KEY_ROWID = "_id"; private static final String TAG = "NotesDbAdapter"; private DatabaseHelper mDbHelper; private SQLiteDatabase mDb; /** * Database creation sql statement */ private static final String DATABASE_CREATE = "create table notes (_id integer primary key autoincrement, " + "title text not null, body text not null, house text not null);"; private static final String DATABASE_NAME = "data"; private static final String DATABASE_TABLE = "notes"; private static final int DATABASE_VERSION = 2; private final Context mCtx; private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(DATABASE_CREATE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion + ", which will destroy all old data"); db.execSQL("DROP TABLE IF EXISTS notes"); onCreate(db); } } /** * Constructor - takes the context to allow the database to be * opened/created * * @param ctx the Context within which to work */ public NotesDbAdapter(Context ctx) { this.mCtx = ctx; } /** * Open the notes database. If it cannot be opened, try to create a new * instance of the database. If it cannot be created, throw an exception to * signal the failure * * @return this (self reference, allowing this to be chained in an * initialization call) * @throws SQLException if the database could be neither opened or created */ public NotesDbAdapter open() throws SQLException { mDbHelper = new DatabaseHelper(mCtx); mDb = mDbHelper.getWritableDatabase(); return this; } public void close() { mDbHelper.close(); } /** * Create a new note using the title and body provided. If the note is * successfully created return the new rowId for that note, otherwise return * a -1 to indicate failure. * * @param title the title of the note * @param body the body of the note * @return rowId or -1 if failed */ public long createNote(String title, String body, String house) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_TITLE, title); initialValues.put(KEY_BODY, body); initialValues.put(KEY_HOUSE, house); return mDb.insert(DATABASE_TABLE, null, initialValues); } /** * Delete the note with the given rowId * * @param rowId id of note to delete * @return true if deleted, false otherwise */ public boolean deleteNote(long rowId) { return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } /** * Return a Cursor over the list of all notes in the database * * @return Cursor over all notes */ public Cursor fetchAllNotes() { return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_BODY, KEY_HOUSE}, null, null, null, null, null); } /** * Return a Cursor positioned at the note that matches the given rowId * * @param rowId id of note to retrieve * @return Cursor positioned to matching note, if found * @throws SQLException if note could not be found/retrieved */ public Cursor fetchNote(long rowId) throws SQLException { Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, KEY_BODY, KEY_HOUSE}, KEY_ROWID + "=" + rowId, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } /** * Update the note using the details provided. The note to be updated is * specified using the rowId, and it is altered to use the title and body * values passed in * * @param rowId id of note to update * @param title value to set note title to * @param body value to set note body to * @return true if the note was successfully updated, false otherwise */ public boolean updateNote(long rowId, String title, String body, String house) { ContentValues args = new ContentValues(); args.put(KEY_TITLE, title); args.put(KEY_BODY, body); args.put(KEY_HOUSE, house); return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; } } 

NoteEdit.xml

  <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TableLayout android:id="@+id/TableLayout01" android:layout_width="fill_parent" android:layout_height="wrap_content" android:stretchColumns="0"> <TableRow android:id="@+id/TableRow01" android:layout_width="wrap_content" android:layout_height="wrap_content"> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="@string/title" /> <EditText android:id="@+id/title" android:layout_height="wrap_content" android:layout_width="wrap_content" android:hint="Montague St."/> </TableRow> <TableRow android:id="@+id/TableRow02" android:layout_width="wrap_content" android:layout_height="wrap_content"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/body" /> <EditText android:id="@+id/body" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:scrollbars="vertical" android:hint="44"/> </TableRow> </TableLayout> <ScrollView android:id="@+id/ScrollView01" android:layout_width="wrap_content" android:layout_height="wrap_content"> <TableLayout android:id="@+id/TableLayout02" android:layout_width="fill_parent" android:layout_height="wrap_content" android:stretchColumns="0"> <TableRow android:id="@+id/TableRow03" android:layout_width="wrap_content" android:layout_height="wrap_content"> <EditText android:id="@+id/house" android:layout_width="fill_parent" android:layout_height="wrap_content" android:hint="House Number"></EditText> <CheckBox android:id="@+id/CheckBox01" android:layout_width="wrap_content" android:layout_height="wrap_content"></CheckBox> </TableRow> <Button android:id="@+id/Button01" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Add House"></Button> </TableLayout> </ScrollView> <LinearLayout android:orientation="horizontal" android:layout_width="wrap_content" android:layout_height="wrap_content"> <Button android:id="@+id/confirm" android:text="@string/confirm" android:layout_width="wrap_content" android:layout_height="wrap_content" /> </LinearLayout> </LinearLayout> 

I understand that my problem is extremely open, and "n00b" is very simple, but any help or even just pushing in the right direction would be appreciated.

thanks

Franc

Answer 1

It looks like what you want is a one-to-many relationship in your data. To do this, you will create another table of type "note_houses", where each entry is a single text entry / "house" with a column note_id, which acts as a foreign key, for example:

 create table note_houses ( _id integer primary key autoincrement, note_id integer not null references notes (_id), entry text not null ) 

When someone clicked a button to add a new record, it should insert a new record in this table (for this you will have to write a createHouse method similar to createNote). A scrolling list of entries below can be generated using a ListView. The cursor for the ListView adapter must be generated from the fetchHousesByNote method in the DbAdapter, which would execute the following request:

 select * from note_houses where note_id=? 

... and you bind the note_id parameter to the identifier of the edited note.

It makes sense? Is this what you are asking for?

Answer 2

Create a method in the database class that allows you to update the record. Then call this method in onClickListener on the button that will read the values ​​and pass them to the database method for updating. It will not be perfect, but should work.