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Difference between Java Enumeration and Iterator
...CC, EEE. ----------------------------------------------------- Vector<String> v=new Vector<String>(6); v.add("AAA"); v.add("BBB"); v.add("CCC"); v.add("DDD"); v.add("EEE"); v.add("FFF"); Enumeration<String> en = v.elements(); while(en.hasMoreElements()) String value=(String) en.n...
Can hash tables really be O(1)?
...ll as the above, if you are using immutable objects as your keys e.g. Java Strings, having calculated the hash once, you can remember it and not have to calculate it again. On the other hand, you can't usually rely on the hash to tell if two keys are equal once you have found the right bucket, so f...
What is the most efficient way to deep clone an object in JavaScript?
...nly supported by Firefox . I've done things like obj = JSON.parse(JSON.stringify(o)); but question the efficiency. I've also seen recursive copying functions with various flaws.
I'm surprised no canonical solution exists.
...
differentiate null=True, blank=True in django
...ngo are never saved as NULL. Blank values are stored in the DB as an empty string ('').
A few examples:
models.DateTimeField(blank=True) # raises IntegrityError if blank
models.DateTimeField(null=True) # NULL allowed, but must be filled out in a form
Obviously, Those two options don't make logi...
simple HTTP server in Java using only Java SE API
...t.httpserver.HttpServer;
public class Test {
public static void main(String[] args) throws Exception {
HttpServer server = HttpServer.create(new InetSocketAddress(8000), 0);
server.createContext("/test", new MyHandler());
server.setExecutor(null); // creates a default e...
Correct way to use StringBuilder in SQL
...
The aim of using StringBuilder, i.e reducing memory. Is it achieved?
No, not at all. That code is not using StringBuilder correctly. (I think you've misquoted it, though; surely there aren't quotes around id2 and table?)
Note that the aim ...
Why is list initialization (using curly braces) better than the alternatives?
...t be converted to another integer that cannot hold its value. For example, char
to int is allowed, but not int to char.
A floating-point value cannot be converted to another floating-point type that cannot hold its
value. For example, float to double is allowed, but not double to float.
A floating-p...
SQL Server indexes - ascending or descending, what difference does it make?
...
CREATE TABLE T1( [ID] [int] IDENTITY NOT NULL,
[Filler] [char](8000) NULL,
PRIMARY KEY CLUSTERED ([ID] ASC))
The Query
SELECT TOP 10 *
FROM T1
ORDER BY ID DESC
Uses an ordered scan with scan direction BACKWARD as can be seen in the Execution Plan. There is a s...
Pass arguments to Constructor in VBA
...e our private properties to be set.
Public Sub InitiateProperties(name as String, age as Integer)
m_name = name
m_age = age
End Sub
And now in the factory module:
Public Function CreateEmployee(name as String, age as Integer) as Employee
Dim employee_obj As Employee
Set employ...
How to evaluate a math expression given in string form?
I'm trying to write a Java routine to evaluate math expressions from String values like:
25 Answers
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