我正在尝试在listView中显示数据库中的结果，这是可点击的长按，项目可以删除，点击后可以转到另一个活动。所以我创建了一个名为editdeletedoctor
的活动public class editdeletedoctor extends Activity {
private ArrayList<String> results = new ArrayList<String>();
private String tableName = TableData.TableInfo.TABLE_DOCTOR;
private SQLiteDatabase newDB;
private ArrayList<doctorClass> doctor_List = new ArrayList<doctorClass>();
public static String MODEL_TO_EDIT = "MODEL_TO_EDIT";
public ListView list;
public ArrayAdapter<String> adapter;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_list);
init();
openAndQueryDatabase();
displayResultList();
}
private void init() {
list = (ListView) findViewById(R.id.list);
list.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
Intent intent = new Intent(editdeletedoctor.this,
registerdoctor.class);
intent.putExtra("theText", doctor_List.get(position).getUsername());
intent.putExtra(editdeletedoctor.MODEL_TO_EDIT,doctor_List.get(position));
editdeletedoctor.this.finish();
startActivity(intent);
}
});
list.setOnItemLongClickListener(new OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view,
final int position, long id) {
Builder dialog = new AlertDialog.Builder(editdeletedoctor.this);
dialog.setTitle("Are you sure you want to delete This doctor?");
dialog.setPositiveButton("Yes", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
doctorClass doctor = doctor_List.get(position);
doctor_List.remove(position);
DatabaseOperations db = new DatabaseOperations(getApplicationContext());
try {
db.open();
HashMap<String, String> conditionKV = new HashMap<String, String>();
conditionKV.put(TableData.TableInfo.DOCTOR_ID, doctor.getId() + "");
db.deleteDoctor(conditionKV);
results.remove(position);
adapter.notifyDataSetChanged();
} catch (SQLiteException se) {
Log.e(getClass().getSimpleName(),
"Could not create or Open the database");
} finally {
if (db != null)
db.close();
}
dialog.dismiss();
}
});
dialog.setNegativeButton("No", new OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
dialog.show();
return false;
}
});
}
private void displayResultList() {
adapter = new ArrayAdapter<String>(this,
android.R.layout.simple_list_item_1, results);
list.setAdapter(adapter);
list.setTextFilterEnabled(true);
}
private void openAndQueryDatabase() {
DatabaseOperations db = new DatabaseOperations(getApplicationContext());
try {
db.open();
doctor_List = db.getDoctor(null);
for (doctorClass inc : doctor_List) {
if(inc.getId()==TableData.TableInfo.userID)
results.add("Name: " + inc.getUsername() + " Phone:"
+ inc.getPhone() + ",Address: "
+ inc.getAddress());
}
} catch (SQLiteException se) {
Log.e(getClass().getSimpleName(),
"Could not create or Open the database");
} finally {
if (db != null)
db.close();
}
}
}
And in the DatabaseOperations.java class :
public DatabaseOperations open() throws SQLException {
ourHelper = new DatabaseOperations(context);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}
public void close() {
ourHelper.close();
}
public ArrayList<doctorClass> getDoctor(HashMap<String, String> conditionKV) {
Cursor m_cursor = get(TableData.TableInfo.TABLE_DOCTOR, conditionKV);
ArrayList<doctorClass> list = new ArrayList<doctorClass>();
if (m_cursor.moveToFirst()) {
do {
doctorClass model = new doctorClass();
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_ID)) != null)
model.setId(m_cursor.getInt(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_ID)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_NAME)) != null)
model.setUsername(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_NAME)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_PASS)) != null)
model.setPassword(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_PASS)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_MAIL)) != null)
model.setEmail(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_MAIL)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_PHONE)) != null)
model.setPhone(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_PHONE)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_ADDRESS)) != null)
model.setAddress(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_ADDRESS)));
if (m_cursor.getString(m_cursor.getColumnIndex(TableData.TableInfo.DOCTOR_GENDER)) != null)
model.setGender(m_cursor.getString(m_cursor
.getColumnIndex(TableData.TableInfo.DOCTOR_GENDER)));
list.add(model);
} while (m_cursor.moveToNext());
}// end if
return list;
}
public Cursor get(String tableName, HashMap<String, String> conditionKV) {
String whereClause = null;
if (conditionKV != null)
whereClause = formatWherecondition(conditionKV);
String completeQuery = "SELECT * FROM " + tableName + " ";
if (whereClause != null) {
completeQuery += " WHERE " + whereClause;
}
return ourDatabase.rawQuery(completeQuery, null);
}
public String formatWherecondition(HashMap<String, String> conditionKV) {
try {
String result = "";
if (conditionKV.size() < 1) {
throw new Exception("Hahsmap condition Empty");
}
Iterator l_iterator = conditionKV.keySet().iterator();
boolean isOneField = false;
while (l_iterator.hasNext()) {
String l_key = (String) l_iterator.next();
String l_value = conditionKV.get(l_key);
if (isOneField)
result = result + " AND ";
result = result + l_key + "='" + l_value + "' ";
isOneField = true;
}
return result;
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
public void deleteDoctor(HashMap<String, String> conditionKV) {
delete(TableData.TableInfo.TABLE_DOCTOR, conditionKV);
}
private void delete(String tableName, HashMap<String, String> conditionKV) {
String whereClause = null;
if (conditionKV == null)
return;
whereClause = formatWherecondition(conditionKV);
String completeQuery = "DELETE FROM " + tableName + " ";
if (whereClause != null) {
completeQuery += " WHERE " + whereClause;
ourDatabase.execSQL(completeQuery);
}
}
运行时出现错误Here is the logcat
请帮帮我。
谢谢
答案 0 :(得分：0)
你确定你在这里使用的“上下文”不是空的吗？
如何以这种方式重写open()函数并通过open(getApplicationContext());调用它？
public DatabaseOperations open(Context context) throws SQLException {
ourHelper = new DatabaseOperations(context);
ourDatabase = ourHelper.getWritableDatabase();
return this;
}