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How to escape text for regular expression in Java
... may lead to unexpected results, for example Pattern.quote("*.wav").replaceAll("*",".*") will result in \Q.*.wav\E and not .*\.wav, as you might expect.
– Matthias Ronge
Jan 16 '13 at 13:27
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Java's L number (long) specification
It appears that when you type in a number in Java, the compiler automatically reads it as an integer, which is why when you type in (long) 6000000000 (not in integer's range) it will complain that 6000000000 is not an integer. To correct this, I had to specify 6000000000L . I just learned abo...
Preview an image before it is uploaded
...file (image) before it is uploaded. The preview action should be executed all in the browser without using Ajax to upload the image.
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Efficient way to remove ALL whitespace from String?
I'm calling a REST API and am receiving an XML response back. It returns a list of a workspace names, and I'm writing a quick IsExistingWorkspace() method. Since all workspaces consist of contiguous characters with no whitespace, I'm assuming the easiest way to find out if a particular workspace i...
Prevent a webpage from navigating away using JavaScript
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Using onunload allows you to display messages, but will not interrupt the navigation (because it is too late). However, using onbeforeunload will interrupt navigation:
window.onbeforeunload = function() {
return "";
}
Note: An empty st...
Super-simple example of C# observer/observable with delegates
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The observer pattern is usually implemented with events.
Here's an example:
using System;
class Observable
{
public event EventHandler SomethingHappened;
public void DoSomething() =>
SomethingHappened?.Invoke(this, EventArgs.Empt...
Immutability of Strings in Java
...t, and changing a reference. s2 still points to the same object as we initially set s1 to point to. Setting s1 to "Help!" only changes the reference, while the String object it originally referred to remains unchanged.
If strings were mutable, we could do something like this:
String s1 = "Hello";
St...
One-liner to recursively list directories in Ruby?
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Dir.glob("**/*/") # for directories
Dir.glob("**/*") # for all files
Instead of Dir.glob(foo) you can also write Dir[foo] (however Dir.glob can also take a block, in which case it will yield each path instead of creating an array).
Ruby Glob Docs
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Converting strings to floats in a DataFrame
...newer version of pandas (0.17 and up), you can use to_numeric function. It allows you to convert the whole dataframe or just individual columns. It also gives you an ability to select how to treat stuff that can't be converted to numeric values:
import pandas as pd
s = pd.Series(['1.0', '2', -3])
p...
Using jquery to get all checked checkboxes with a certain class name
I know I can get all checked checkboxes on a page using this:
16 Answers
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