Android 无法使用操作栏将项添加到listview
对于我正在尝试制作的应用程序，用户将按下操作栏中的加号图标，并弹出一个带有编辑文本的自定义警报对话框，要求用户输入文本。输入文本并单击“添加”后，应向listview添加一个项目，其中包含用户在edittext中输入的文本。我使用了Android开发中心的记事本示例，并对代码进行了修改，以使其符合我的喜好。但问题是，当我按下“添加”按钮时，没有任何变化。它根本不添加列表项 Notepadv2.javaAndroid 无法使用操作栏将项添加到listview,android,listview,android-actionbar,android-alertdialog,Android,Listview,Android Actionbar,Android Alertdialog,对于我正在尝试制作的应用程序，用户将按下操作栏中的加号图标，并弹出一个带有编辑文本的自定义警报对话框，要求用户输入文本。输入文本并单击“添加”后，应向listview添加一个项目，其中包含用户在edittext中输入的文本。我使用了Android开发中心的记事本示例，并对代码进行了修改，以使其符合我的喜好。但问题是，当我按下“添加”按钮时，没有任何变化。它根本不添加列表项 Notepadv2.java public class Notepadv2 extends ListActivity {
public class Notepadv2 extends ListActivity {
private static final int ACTIVITY_CREATE=0;
private static final int ACTIVITY_EDIT=1;
private static final int INSERT_ID = Menu.FIRST;
private static final int DELETE_ID = Menu.FIRST + 1;
private NotesDbAdapter mDbHelper;
private Cursor mNotesCursor;
private EditText mTitleText;
private Long mRowId;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes_list);
mDbHelper = new NotesDbAdapter(this);
mDbHelper.open();
fillData();
registerForContextMenu(getListView());
mRowId = null;
Bundle extras = getIntent().getExtras();
if (extras != null) {
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mRowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (title != null) {
mTitleText.setText(title);
}
}
}
private void fillData() {
// Get all of the rows from the database and create the item list
mNotesCursor = mDbHelper.fetchAllNotes();
startManagingCursor(mNotesCursor);
// Create an array to specify the fields we want to display in the list (only TITLE)
String[] from = new String[]{NotesDbAdapter.KEY_TITLE};
// and an array of the fields we want to bind those fields to (in this case just text1)
int[] to = new int[]{R.id.text1};
// Now create a simple cursor adapter and set it to display
SimpleCursorAdapter notes =
new SimpleCursorAdapter(this, R.layout.notes_row, mNotesCursor, from, to);
setListAdapter(notes);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.INSERT_ID:
createNote();
break;
}
return true;
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
menu.add(0, DELETE_ID, 0, R.string.menu_delete);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
switch(item.getItemId()) {
case DELETE_ID:
AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
mDbHelper.deleteNote(info.id);
fillData();
return true;
}
return super.onContextItemSelected(item);
}
private void createNote()
{
Context context = Notepadv2.this;
AlertDialog.Builder alert = new AlertDialog.Builder(context);
alert.setTitle("Add note");
alert.setMessage("Enter text here");
// Set an EditText view to get user input
final EditText input = new EditText(this);
alert.setView(input);
alert.setPositiveButton(R.string.alert_dialog_ok, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, input.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
}
});
alert.setNegativeButton(R.string.alert_dialog_cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
/* User clicked Cancel so do some stuff */
}
});
alert.create();
alert.show();
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Cursor c = mNotesCursor;
c.moveToPosition(position);
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, mTitleText.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
Bundle extras = intent.getExtras();
switch(requestCode) {
case ACTIVITY_CREATE:
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.createNote(title);
fillData();
break;
case ACTIVITY_EDIT:
Long rowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (rowId != null) {
String editTitle = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.updateNote(rowId, editTitle);
}
fillData();
break;
}
}
}
public class NotesDbAdapter {
public static final String KEY_TITLE = "title";
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);";
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) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TITLE, title);
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}, 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_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) {
ContentValues args = new ContentValues();
args.put(KEY_TITLE, title);
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
public class Notepadv2 extends ListActivity {
private static final int ACTIVITY_CREATE=0;
private static final int ACTIVITY_EDIT=1;
private static final int INSERT_ID = Menu.FIRST;
private static final int DELETE_ID = Menu.FIRST + 1;
private NotesDbAdapter mDbHelper;
private Cursor mNotesCursor;
private EditText mTitleText;
private Long mRowId;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes_list);
mDbHelper = new NotesDbAdapter(this);
mDbHelper.open();
fillData();
registerForContextMenu(getListView());
mRowId = null;
Bundle extras = getIntent().getExtras();
if (extras != null) {
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mRowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (title != null) {
mTitleText.setText(title);
}
}
}
private void fillData() {
// Get all of the rows from the database and create the item list
mNotesCursor = mDbHelper.fetchAllNotes();
startManagingCursor(mNotesCursor);
// Create an array to specify the fields we want to display in the list (only TITLE)
String[] from = new String[]{NotesDbAdapter.KEY_TITLE};
// and an array of the fields we want to bind those fields to (in this case just text1)
int[] to = new int[]{R.id.text1};
// Now create a simple cursor adapter and set it to display
SimpleCursorAdapter notes =
new SimpleCursorAdapter(this, R.layout.notes_row, mNotesCursor, from, to);
setListAdapter(notes);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.INSERT_ID:
createNote();
break;
}
return true;
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
menu.add(0, DELETE_ID, 0, R.string.menu_delete);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
switch(item.getItemId()) {
case DELETE_ID:
AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
mDbHelper.deleteNote(info.id);
fillData();
return true;
}
return super.onContextItemSelected(item);
}
private void createNote()
{
Context context = Notepadv2.this;
AlertDialog.Builder alert = new AlertDialog.Builder(context);
alert.setTitle("Add note");
alert.setMessage("Enter text here");
// Set an EditText view to get user input
final EditText input = new EditText(this);
alert.setView(input);
alert.setPositiveButton(R.string.alert_dialog_ok, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, input.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
}
});
alert.setNegativeButton(R.string.alert_dialog_cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
/* User clicked Cancel so do some stuff */
}
});
alert.create();
alert.show();
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Cursor c = mNotesCursor;
c.moveToPosition(position);
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, mTitleText.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
Bundle extras = intent.getExtras();
switch(requestCode) {
case ACTIVITY_CREATE:
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.createNote(title);
fillData();
break;
case ACTIVITY_EDIT:
Long rowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (rowId != null) {
String editTitle = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.updateNote(rowId, editTitle);
}
fillData();
break;
}
}
}
public class NotesDbAdapter {
public static final String KEY_TITLE = "title";
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);";
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) {
ContentValues initialValues = new ContentValues();
initialValues.put(KEY_TITLE, title);
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}, 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_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) {
ContentValues args = new ContentValues();
args.put(KEY_TITLE, title);
return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0;
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ListView android:id="@+id/android:list"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
<TextView android:id="@+id/android:empty"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:text="@string/no_notes"/>
</LinearLayout>
<?xml version="1.0" encoding="utf-8"?>
<TextView android:id="@+id/text1" xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:padding="12dp"/>
如果有人知道我可以用什么代码替换我的代码来解决这个问题，我们将不胜感激。谢谢 notices.notifyDataSetChanged（）如何？它告诉listview数据已经更改。我考虑过了…但我不知道在哪里实现它。我修复了代码。常量int“RESULT_OK”的值是多少？如果代码仍然无法工作，请尝试将“setResult（RESULT_OK，minent）；”替换为“setResult（ACTIVITY_CREATE，minent）；”我尝试了这一点，并添加了
notes.notifyDataSetChanged（）但两者都不起作用如果有任何帮助，当我按下“添加”按钮时，我检查了日志cat，这就是我得到的结果，因此我添加了setResult（ACTIVITY_CREATE，minent）和notes.notifyDataSetChanged（）到代码，但我仍然得到相同的结果。当我点击“添加”时，什么也没发生。有人有其他想法吗？因为我迷路了
public class Notepadv2 extends ListActivity {
private static final int ACTIVITY_CREATE=0;
private static final int ACTIVITY_EDIT=1;
private static final int INSERT_ID = Menu.FIRST;
private static final int DELETE_ID = Menu.FIRST + 1;
private NotesDbAdapter mDbHelper;
private Cursor mNotesCursor;
private EditText mTitleText;
private Long mRowId;
private SimpleCursorAdapter notes;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.notes_list);
mDbHelper = new NotesDbAdapter(this);
mDbHelper.open();
fillData();
registerForContextMenu(getListView());
mRowId = null;
Bundle extras = getIntent().getExtras();
if (extras != null) {
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mRowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (title != null) {
mTitleText.setText(title);
}
}
}
private void fillData() {
// Get all of the rows from the database and create the item list
mNotesCursor = mDbHelper.fetchAllNotes();
startManagingCursor(mNotesCursor);
// Create an array to specify the fields we want to display in the list (only TITLE)
String[] from = new String[]{NotesDbAdapter.KEY_TITLE};
// and an array of the fields we want to bind those fields to (in this case just text1)
int[] to = new int[]{R.id.text1};
// Now create a simple cursor adapter and set it to display
notes = new SimpleCursorAdapter(this, R.layout.notes_row, mNotesCursor, from, to);
setListAdapter(notes);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle item selection
switch (item.getItemId()) {
case R.id.INSERT_ID:
createNote();
break;
}
return true;
}
@Override
public void onCreateContextMenu(ContextMenu menu, View v,
ContextMenuInfo menuInfo) {
super.onCreateContextMenu(menu, v, menuInfo);
menu.add(0, DELETE_ID, 0, R.string.menu_delete);
}
@Override
public boolean onContextItemSelected(MenuItem item) {
switch(item.getItemId()) {
case DELETE_ID:
AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
mDbHelper.deleteNote(info.id);
fillData();
return true;
}
return super.onContextItemSelected(item);
}
private void createNote()
{
Context context = Notepadv2.this;
AlertDialog.Builder alert = new AlertDialog.Builder(context);
alert.setTitle("Add note");
alert.setMessage("Enter text here");
// Set an EditText view to get user input
final EditText input = new EditText(this);
alert.setView(input);
alert.setPositiveButton(R.string.alert_dialog_ok, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, input.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
notes.notifyDataSetChanged();
}
});
alert.setNegativeButton(R.string.alert_dialog_cancel, new DialogInterface.OnClickListener() {
public void onClick(DialogInterface dialog, int whichButton) {
/* User clicked Cancel so do some stuff */
}
});
alert.create();
alert.show();
}
@Override
protected void onListItemClick(ListView l, View v, int position, long id) {
super.onListItemClick(l, v, position, id);
Cursor c = mNotesCursor;
c.moveToPosition(position);
Bundle bundle = new Bundle();
bundle.putString(NotesDbAdapter.KEY_TITLE, mTitleText.getText().toString());
if (mRowId != null) {
bundle.putLong(NotesDbAdapter.KEY_ROWID, mRowId);
}
Intent mIntent = new Intent();
mIntent.putExtras(bundle);
setResult(RESULT_OK, mIntent);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent intent) {
super.onActivityResult(requestCode, resultCode, intent);
Bundle extras = intent.getExtras();
switch(requestCode) {
case ACTIVITY_CREATE:
String title = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.createNote(title);
fillData();
break;
case ACTIVITY_EDIT:
Long rowId = extras.getLong(NotesDbAdapter.KEY_ROWID);
if (rowId != null) {
String editTitle = extras.getString(NotesDbAdapter.KEY_TITLE);
mDbHelper.updateNote(rowId, editTitle);
}
fillData();
break;
}
}
}