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What is a NullPointerException, and how do I fix it?
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When you declare a reference variable (i.e. an object) you are really creating a pointer to an object. Consider the following code where you declare a variable of primitive type int:
int x;
x = 10;
In this example, the variable x is an int and Java will initialize it to 0 for you. When yo...
How do you crash a JVM?
...ught that you could do so by writing an infinite for-loop that would eventually use up all the memory.
27 Answers
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JavaScript - get the first day of the week from current date
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This is great except this function should be called "setToMonday" as it modifies the date object passed in. getMonday, would return a new Date that is the monday based on the date passed in. A subtle difference, but one that caught me after using this function. Easiest f...
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...
Best way to do Version Control for MS Excel
...lution here.
The solution for me was to create a spreadsheet that exports all modules on save, and removes and re-imports the modules on open. Yes, this could be potentially dangerous for converting existing spreadsheets.
This allows me to edit the macros in the modules via Emacs (yes, emacs) or n...
What are CN, OU, DC in an LDAP search?
...N = Common Name
OU = Organizational Unit
DC = Domain Component
These are all parts of the X.500 Directory Specification, which defines nodes in a LDAP directory.
You can also read up on LDAP data Interchange Format (LDIF), which is an alternate format.
You read it from right to left, the right-m...
Swift - encode URL
...= "test/test"
let escapedString = originalString.addingPercentEncoding(withAllowedCharacters: .urlHostAllowed)
print(escapedString!)
Output:
test%2Ftest
Swift 1
In iOS 7 and above there is stringByAddingPercentEncodingWithAllowedCharacters
var originalString = "test/test"
var escapedString...
Multiple ModelAdmins/views for same model in Django admin
...l may be registered only once.
class PostAdmin(admin.ModelAdmin):
list_display = ('title', 'pubdate','user')
class MyPost(Post):
class Meta:
proxy = True
class MyPostAdmin(PostAdmin):
def get_queryset(self, request):
return self.model.objects.filter(user = request.user...
Windows 7 SDK installation failure
I seem to be completely unable to install the Windows 7 SDK onto my machine, and the only solution I've found on the web is to make a swathe of registry changes. I've done this - still no success.
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What does “./bin/www” do in Express 4.x?
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In Express 3.0, you normally would use app.configure() (or app.use()) to set up the required middleware you need. Those middleware you specified are bundled together with Express 3.0.
Example:
var express = require('express');
var routes = require...