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NullPointerException accessing views in onCreate()
...d-generated code.
The view is in the fragment layout (fragment_main.xml) and not in the activity layout (activity_main.xml). onCreate() is too early in the lifecycle to find it in the activity view hierarchy, and a null is returned. Invoking a method on null causes the NPE.
The preferred solution...
How do you split a list into evenly sized chunks?
I have a list of arbitrary length, and I need to split it up into equal size chunks and operate on it. There are some obvious ways to do this, like keeping a counter and two lists, and when the second list fills up, add it to the first list and empty the second list for the next round of data, but t...
Offset a background image from the right using CSS
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It works now on mobile devices (checked on Android, iOS and WindowsPhone). Still Safari 5.1.7 not support background position given like here.
– Szorstki
Apr 15 '14 at 13:33
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calling non-static method in static method in Java [duplicate]
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@EJP For security purposes, and this is what I do with my project, in the case of dependency injection, it is useful to only have initialization code be instantiated for initialization, and not at the arbitrary discretion of code using my API. Thus, whe...
Checking if an object is null in C#
... List<Object>();
Even better: since it's a field, make it private. And if there's nothing preventing you, make it also readonly. Just good practice.
Aside
The correct way to check for nullity is if(data != null). This kind of check is ubiquitous for reference types; even Nullable<T> ...
Unix - create path of folders and file
I know you can do mkdir to create a directory and touch to create a file, but is there no way to do both operations in one go?
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Is there a way to get the XPath in Google Chrome?
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I guess Chrome copied most of the Firebug command-line commands: getfirebug.com/wiki/index.php/Command_Line_API
– huyz
Sep 3 '11 at 8:35
102
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initialize a numpy array
Is there way to initialize a numpy array of a shape and add to it? I will explain what I need with a list example. If I want to create a list of objects generated in a loop, I can do:
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Extract a substring according to a pattern
...we create a data frame with two columns, one for the part before the colon and one for after, and then extract the latter.
library(dplyr)
library(tidyr)
library(purrr)
DF <- data.frame(string)
DF %>%
separate(string, into = c("pre", "post")) %>%
pull("post")
## [1] "E001" "E002" "E00...
How to convert a DOM node list to an array in Javascript?
...es, but it expects a Javascript array (it runs some Array methods on that) and I want to feed it the output of Document.getElementsByTagName that returns a DOM node list.
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