如何使这段代码无重复? 这种方法很相似。如何重写这种方法而不重复?
方法来创建电话号码:
private List<String> createPhoneNumbers(String sqlStatement, Long id) {
List<String> phones = new ArrayList<>();
try (PreparedStatement statement = this.connection.prepareStatement(sqlStatement)) {
statement.setLong(1, id);
try (ResultSet resultSet = statement.executeQuery()) {
while (resultSet.next()) {
phones.add(resultSet.getString("phoneNumber"));
}
return phones;
}
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
方法来创建好友列表:
private List<Account> createFriendList(String sqlStatement, Long id) {
List<Account> friends = new ArrayList<>();
try (PreparedStatement statement = this.connection.prepareStatement(sqlStatement)) {
statement.setLong(1, id);
try (ResultSet resultSet = statement.executeQuery()) {
while (resultSet.next()) {
friends.add(createSimpleElement(resultSet));
}
return friends;
}
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
方法来创建群组列表:
private List<Group> createGroupList(String sqlStatement, Long id) {
List<Group> groups = new ArrayList<>();
try (PreparedStatement statement = this.connection.prepareStatement(sqlStatement)) {
statement.setLong(1, id);
try (ResultSet resultSet = statement.executeQuery()) {
while (resultSet.next()) {
groups.add(createGroupFromResultSet(resultSet));
}
return groups;
}
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
这是我很不好解决。
//field values: 1- create String, 2 - createAccount, 3 - createGroup
private <E> List<E> createList(String selectSql, Long id, int field) {
List<E> list = new ArrayList<>();
try (PreparedStatement statement = this.connection.prepareStatement(selectSql)) {
statement.setLong(1, id);
try (ResultSet resultSet = statement.executeQuery()) {
while (resultSet.next()) {
switch (field) {
case 1:
list.add((E) resultSet.getString("phoneNumber"));
break;
case 2:
list.add((E) createSimpleElement(resultSet));
break;
case 3:
list.add((E) createGroupFromResultSet(resultSet));
break;
}
}
return list;
}
} catch (SQLException e) {
e.printStackTrace();
return null;
}
}
我能读什么来解决我的代码中的类似问题?
不要。有一种方法可以做一件事,做得很好。如果需要的话,你总是可以使用接口或抽象类。 –
你可以阅读设计模式,并通过编写代码尝试 ,https://www.tutorialspoint.com/design_pattern/ – saurabh