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Using a strategy pattern and a command pattern
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I'm including an encapsulation hierarchy table of several of the GoF design patterns to help explain the differences between these two patterns. Hopefully it better illustrates what each encapsulates so my explanation makes more sense.
First off, the hierarchy list...
Creating a “logical exclusive or” operator in Java
...me result. Therefore, no need for distinct operators. The simplified truth table for a XOR operator is X ^ !X = 1. You cannot short circuit an input in XOR because you have to determine whether the inputs are different. It is a lot easier to understand if you know the fabrication of the actual XOR g...
What is lazy loading in Hibernate?
...e child when parent is loaded from the database.
Example :
If you have a TABLE ? EMPLOYEE mapped to Employee object and contains set of Address objects.
Parent Class : Employee class,
Child class : Address Class
public class Employee {
private Set address = new HashSet(); // contains set of ch...
count the frequency that a value occurs in a dataframe column
... x 1 columns]
See the online docs: http://pandas.pydata.org/pandas-docs/stable/groupby.html
Also value_counts() as @DSM has commented, many ways to skin a cat here
In [38]:
df['a'].value_counts()
Out[38]:
b 3
a 2
s 2
dtype: int64
If you wanted to add frequency back to the original d...
How can I get the timezone name in JavaScript?
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@DanielCompton oh I didn't know about this table, thanks for correcting it again.
– CommonSenseCode
Sep 3 '18 at 7:34
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JPA - Returning an auto generated id after persist()
... Its not working giving zero as a Return after persisting the data into table. either refresh is not working at this case .. What should i do for this. please suggest a way... Thank you
– Vikrant Kashyap
Jun 13 '16 at 6:57
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What version of javac built my jar?
...iszewski' https://stackoverflow.com/a/3313839/1497139 class number version table to create a bash script jarv to show the versions of all class files in a jar file.
usage
usage: ./jarv jarfile
-h|--help: show this usage
Example
jarv $Home/.m2/repository/log4j/log4j/1.2.17/log4j-1.2.17.jar
jav...
What does SQL clause “GROUP BY 1” mean?
...d name, you may also group by ordinal, or position of the field within the table. 1 corresponds to the first field (regardless of name), 2 is the second, and so on.
This is generally ill-advised if you're grouping on something specific, since the table/view structure may change. Additionally, it ma...
How to get UITableView from UITableViewCell?
I have a UITableViewCell which is linked to an object and I need to tell if the cell is visible. From the research I've done, this means I need to somehow access the UITableView that contains it (from there, there are several ways to check if it's visible). So I'm wondering if UITableViewCell ...
Biggest GWT Pitfalls? [closed]
...nnot inspect (inside my IntelliJ debugger) what's happening in the GWT EXT table class... All you can see is that it's a JavaScriptObject. This makes it quite difficult to figure out what's gone wrong...
Not having someone on your team who knows CSS. From my experience, it didn't matter that the per...