当我访问delete方法时，我的应用程序强制关闭，它与insert和get items方法一起工作正常。 在databasehandler中，
public class DatabaseHandler extends SQLiteOpenHelper {
private static final int DB_VERSION = 1;
private static final String DB_NAME = "mydb";
private static final String TABLE_NAME = "mytable";
private static final String _id = "_id";
private static final String name = "name";
public DatabaseHandler(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTableQuery = "create table " + TABLE_NAME + "(" + _id
+ " INTEGER PRIMARY KEY," + name + " TEXT)";
db.execSQL(createTableQuery);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists " + TABLE_NAME);
onCreate(db);
}
public void insertData(String label) {
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(name, label);
db.insert(TABLE_NAME, null, values);
db.close();
}
public void deleteData(String item){
SQLiteDatabase db =this.getWritableDatabase();
//db.delete(TABLE_NAME, name+ "='" +item +"'", null);
db.execSQL("DELETE FROM TABLE_NAME WHERE name='"+item+"'");
db.close();
}
public Set<String> getAllData() {
Set<String> set = new HashSet<String>();
String selectQuery = "select * from " + TABLE_NAME;
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery(selectQuery, null);
if (cursor.moveToFirst()) {
do {
set.add(cursor.getString(1));
} while (cursor.moveToNext());
}
cursor.close();
db.close();
return set;
}
}
在我的活动中，我有这个和
public void onItemSelected(AdapterView<?> parent, View v, int position,
long id) {
String deleteitem = parent.getItemAtPosition(position).toString();
db.deleteData(deleteitem);
loadSpinner();
}
如果我从我的活动中删除“db.deleteData（deleteitem）;”，它没有任何问题。我不知道我错在哪里。一切似乎都很好。
05-17 16:44:01.855: E/AndroidRuntime(1936): FATAL EXCEPTION: main
05-17 16:44:01.855: E/AndroidRuntime(1936): android.database.sqlite.SQLiteException: no such table: TABLE_NAME: DELETE FROM TABLE_NAME WHERE name='Hi i am not available now. i will contact you soon.'
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.database.sqlite.SQLiteDatabase.native_execSQL(Native Method)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1763)
05-17 16:44:01.855: E/AndroidRuntime(1936): at com.praveenkutti1990.ezmesseger.DatabaseHandler.deleteData(DatabaseHandler.java:50)
05-17 16:44:01.855: E/AndroidRuntime(1936): at com.praveenkutti1990.ezmesseger.ListActivity.onItemSelected(ListActivity.java:90)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.widget.AdapterView.fireOnSelected(AdapterView.java:871)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.widget.AdapterView.access$200(AdapterView.java:42)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.widget.AdapterView$SelectionNotifier.run(AdapterView.java:837)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.os.Handler.handleCallback(Handler.java:587)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.os.Handler.dispatchMessage(Handler.java:92)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.os.Looper.loop(Looper.java:123)
05-17 16:44:01.855: E/AndroidRuntime(1936): at android.app.ActivityThread.main(ActivityThread.java:3683)
05-17 16:44:01.855: E/AndroidRuntime(1936): at java.lang.reflect.Method.invokeNative(Native Method)
05-17 16:44:01.855: E/AndroidRuntime(1936): at java.lang.reflect.Method.invoke(Method.java:507)
05-17 16:44:01.855: E/AndroidRuntime(1936): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-17 16:44:01.855: E/AndroidRuntime(1936): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-17 16:44:01.855: E/AndroidRuntime(1936): at dalvik.system.NativeStart.main(Native Method)
05-17 16:44:03.945: I/Process(1936): Sending signal. PID: 1936 SIG: 9
我的活动
public class ListActivity extends Activity implements OnClickListener,
OnItemSelectedListener {
private EditText edittext;
private Button btnAdd;
DatabaseHandler db;
private Spinner spinner;
ArrayAdapter<String> adapter;
List<String> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.list);
db = new DatabaseHandler(ListActivity.this);
edittext = (EditText) findViewById(R.id.editText1);
btnAdd = (Button) findViewById(R.id.btnadd);
spinner = (Spinner) findViewById(R.id.spinner);
btnAdd.setOnClickListener(this);
spinner.setOnItemSelectedListener(this);
loadSpinner();
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
String name = edittext.getText().toString().trim();
if (TextUtils.isEmpty(name)) {
edittext.setError("Enter a valid Message");
edittext.requestFocus();
} else {
db.insertData(name);
edittext.setText("");
// Hiding the keyboard
InputMethodManager inputmangager = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
inputmangager.hideSoftInputFromWindow(edittext.getWindowToken(), 0);
}
Toast.makeText(getApplicationContext(),"Template added Successfully", 0).show();
Intent in = new Intent(ListActivity.this,MainActivity.class);
startActivity(in);
finish();
}
@Override
public void onItemSelected(AdapterView<?> parent, View v, int position,
long id) {
String deleteitem = parent.getItemAtPosition(position).toString();
//db.deleteData(deleteitem);
loadSpinner();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
private void loadSpinner() {
// TODO Auto-generated method stub
Set<String> set = db.getAllData();
List<String> list = new ArrayList<String>(set);
adapter = new ArrayAdapter<String>(ListActivity.this,
android.R.layout.simple_spinner_item, list);
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
spinner.setAdapter(adapter);
spinner.setWillNotDraw(false);
}
}
答案 0 :(得分：3)
尝试改变
db.delete(TABLE_NAME, name+ "=" +item, null);
这一行
db.delete(TABLE_NAME, name+ "=?", new String[] { (item) });
像这样或者
db.delete(TABLE_NAME, name+ "='" +item+"'", null);
我认为您在申请中没有使用btnAdd。如果是，请删除
btnAdd = (Button) findViewById(R.id.btnadd);
这一行。并从
中删除评论符号（//）
//db.deleteData(deleteitem);
这一行。
并且还要改变
String createTableQuery = "create table " + TABLE_NAME + "(" + _id
+ " INTEGER PRIMARY KEY," + name + " TEXT)";
这一行
String createTableQuery = "create table " + TABLE_NAME + " (" + _id
+ " INTEGER PRIMARY KEY," + name + " TEXT)";
TABLE_NAME和(之间的空格。
让我知道会发生什么。
答案 1 :(得分：0)
只是'错过了这样的字符串：
db.delete(TABLE_NAME, name+ "='" +item + "'", null);
您正在删除SQL中需要放置的字符串。
更新：
只需改变一下：
db.execSQL("DELETE FROM TABLE_NAME WHERE name='"+item+"'");
by：
db.execSQL("DELETE FROM " + TABLE_NAME + " WHERE name='"+item+"'");
答案 2 :(得分：0)
我更喜欢execSQL：
db.execSQL("DELETE FROM x WHERE y='"+z+"'");