大约有 19,599 项符合查询结果（耗时：0.0346秒） [XML]
How to parse a string to an int in C++?
...still a couple of other problems.
What if the number in the string is not base 10? We can try to accommodate other bases by setting the stream to the correct mode (e.g. ss << std::hex) before trying the conversion. But this means the caller must know a priori what base the number is -- and ho...
How do I initialize the base (super) class?
...asses are derived from object and are what you are using, and invoke their base class through super(), e.g.
class X(object):
def __init__(self, x):
pass
def doit(self, bar):
pass
class Y(X):
def __init__(self):
super(Y, self).__init__(123)
def doit(self, foo):
return supe...
JavaScript Chart Library
...s of JavaScript solutions for graphics that do not require Flash:
Canvas-based, rendered in IE using ExplorerCanvas that in turns relies on VML
SVG on standard-based browsers, rendered as VML in IE
There are pros and cons of both approaches but for a charting library I would recommend the later ...
How to inherit constructors?
Imagine a base class with many constructors and a virtual method
14 Answers
14
...
Connecting to remote URL which requires authentication using Java
...pass = username + ":" + password;
String basicAuth = "Basic " + new String(Base64.getEncoder().encode(userpass.getBytes()));
uc.setRequestProperty ("Authorization", basicAuth);
InputStream in = uc.getInputStream();
share
...
Is it unnecessary to put super() in constructor?
...) is a compiler error so it must be specified.
For example:
public class Base { }
public class Derived extends Base { }
This is fine because if you add no constructor explicitly Java puts in a public default constructor for you.
public class Base { }
public class Derived extends Base { public D...
Check if a table exists in Rails
...tables/views, collectively data sources.
# Tables and views
ActiveRecord::Base.connection.data_sources
ActiveRecord::Base.connection.data_source_exists? 'kittens'
# Tables
ActiveRecord::Base.connection.tables
ActiveRecord::Base.connection.table_exists? 'kittens'
# Views
ActiveRecord::Base.connect...
How to execute a raw update sql with dynamic binding in rails
...ing connection and using it's methods, e.g. for MySQL:
st = ActiveRecord::Base.connection.raw_connection.prepare("update table set f1=? where f2=? and f3=?")
st.execute(f1, f2, f3)
st.close
I'm not sure if there are other ramifications to doing this (connections left open, etc). I would trace the...
What are metaclasses in Python?
...tributes of the class-to-be. The metaclass is determined by looking at the baseclasses of the class-to-be (metaclasses are inherited), at the __metaclass__ attribute of the class-to-be (if any) or the __metaclass__ global variable. The metaclass is then called with the name, bases and attributes of ...
multiple packages in context:component-scan, spring config
...
The following approach is correct:
<context:component-scan base-package="x.y.z.service, x.y.z.controller" />
Note that the error complains about x.y.z.dao.daoservice.LoginDAO, which is not in the packages mentioned above, perhaps you forgot to add it:
<context:component-sca...