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How to read all files in a folder from Java?
...e/you/Desktop");
listFilesForFolder(folder);
Files.walk API is available from Java 8.
try (Stream<Path> paths = Files.walk(Paths.get("/home/you/Desktop"))) {
paths
.filter(Files::isRegularFile)
.forEach(System.out::println);
}
The example uses try-with-resources patte...
cartesian product in pandas
... you can produce a cartesian product using merge (like you would in SQL).
from pandas import DataFrame, merge
df1 = DataFrame({'key':[1,1], 'col1':[1,2],'col2':[3,4]})
df2 = DataFrame({'key':[1,1], 'col3':[5,6]})
merge(df1, df2,on='key')[['col1', 'col2', 'col3']]
Output:
col1 col2 col3
0 ...
How can I lock a file using java (if possible)
... opens a file using a FileReader. How can I prevent another (Java) process from opening this file, or at least notify that second process that the file is already opened? Does this automatically make the second process get an exception if the file is open (which solves my problem) or do I have to ex...
How can I check file size in Python?
....stat. You can get it by either using pathlib (Python 3.4+):
>>> from pathlib import Path
>>> Path('somefile.txt').stat()
os.stat_result(st_mode=33188, st_ino=6419862, st_dev=16777220, st_nlink=1, st_uid=501, st_gid=20, st_size=1564, st_atime=1584299303, st_mtime=1584299400, st_ct...
When to use PNG or JPG in iPhone development?
... extra CPU energy to display. However, large PNGs may take longer to read from storage than more compressed image formats, and thus be slower to display.
JPG's are smaller to store, but lossy (amount depends on compression level), and to display them requires a much more complicated decoding algor...
How to override trait function and call it from the overridden function?
...n calc($v) {
return parent::calc($v*3);
}
}
// .... other code from above
print (new MyTraitChildClass())->calc(2); // will print 8 (2*3 + 2)
You can also provide for ways to override, but still access the trait method as follows:
trait A {
function trait_calc($v) {
ret...
What do the terms “CPU bound” and “I/O bound” mean?
...ght become I/O bound, since the bottleneck is then the reading of the data from disk (actually, this example is perhaps kind of old-fashioned these days with hundreds of MB/s coming in from SSDs).
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Window Features - 更多技术 - 清泛网 - 专注C/C++及内核技术
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Clipping
The system does not automatically clip a child window from the parent window's client area. This means the parent window draws over the child window if it carries out any drawing in the same location as the child window. However, the system does clip the child window from the pa...
Repository Pattern Step by Step Explanation [closed]
...ects are persisted. All of the knowledge of persistence, including mapping from tables to objects, is safely contained in the repository.
Very often, you will find SQL queries scattered in the codebase and when you come to add a column to a table you have to search code files to try and find usages...
How to use multiple AWS Accounts from the command line?
...46053/1199564) because it allows a user to understand how to move settings from one profile to another if, for example, you started out with only the default profile and want to continue with dedicated, separate profiles.
– mgd
Mar 14 '18 at 8:24
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