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Understanding checked vs unchecked exceptions in Java
...be used at all. They were eliminated in C# for example, and most languages don't have them. So you can always throw a subclass of RuntimeException (unchecked exception)
However, I think checked exceptions are useful - they are used when you want to force the user of your API to think how to handle ...
PHP global in functions
...cope to the global scope (statics, singletons, registries, constants). You do not want to use them. A function call should not have to rely on anything outside, e.g.
function fn()
{
global $foo; // never ever use that
$a = SOME_CONSTANT // do not use that
$b = Foo::S...
Echo a blank (empty) line to the console from a Windows batch file [duplicate]
When outputting status messages to the console from a Windows batch file, I want to output blank lines to break up the output. How do I do this?
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What is java interface equivalent in Ruby?
Can we expose interfaces in Ruby like we do in java and enforce the Ruby modules or classes to implement the methods defined by interface.
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Evenly space multiple views within a container view
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So my approach allows you to do this in interface builder. What you do is create 'spacer views' that you have set to match heights equally. Then add top and bottom constraints to the labels (see the screenshot).
More specifically, I have a top const...
How to delete history of last 10 commands in shell?
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If you do this with vim you may find your deletion history in ~/.viminfo so be sure to remove that too!
– waltwood
Jul 22 '15 at 22:39
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How do I set the size of an HTML text box?
How do I set the size of an HTML text box?
11 Answers
11
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PSQLException: current transaction is aborted, commands ignored until end of transaction block
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I got this error using Java and PostgreSQL doing an insert on a table. I will illustrate how you can reproduce this error:
org.postgresql.util.PSQLException: ERROR:
current transaction is aborted, commands ignored until end of transaction block
Summary:
The reason ...
How do you query for “is not null” in Mongo?
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This will return all documents with a key called "IMAGE URL", but they may still have a null value.
db.mycollection.find({"IMAGE URL":{$exists:true}});
This will return all documents with both a key called "IMAGE URL" and a non-null value.
db.my...
Using a piano keyboard as a computer keyboard [closed]
...ed 30 different computer keyboards which all caused me pain. Playing piano does not cause me pain. I have played piano for around 20 years without any pain issues. I would like to know if there is a way to capture MIDI from a MIDI keyboard and output keyboard strokes. I know nothing at all about MID...