Learn about several methods to remove items in a loop from a java collection.
“Puns are the highest form of literature.”
― Alfred Hitchcock
When you have a List or a Set or any other Collection, you may sometimes need to remove items in a loop. For example, you may be maintaining a list of messages for processing, and need to occasionally purge stale items from the list. In such a scenario, you would loop around the collection and remove the stale items.
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Use Java 8 Optional to avoid unexpected conditions like NPE in your code.
“Life always begins with one step outside of your comfort zone.”
― Shannon L. Alder
Java version 1.8 provides the new class Optional which represents an abstration of an optional value. That is the object may contain a value or a
null. This class provides several useful features which help java programmers avoid NullPointerException. Let us look into this class in more detail.
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A ListIterator allows traversal of a Java ArrayList in forward or backward direction.
“A man devoid of hope and conscious of being so has ceased to belong to the future.”
― Albert Camus, The Myth of Sisyphus and Other Essays
Java’s ArrayList class provides a list iterator which allows, among other things, traversal of the list in either direction. This is in comparison to a normal Iterator that allows traversal of the list in forward direction only. In this article, we delve into the usage and behavior of the ListIterator when used with an ArrayList.
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Easily search a java list using java 8 predicate functions.
“Make improvements, not excuses. Seek respect, not attention.”
― Roy T. Bennett, The Light in the Heart
Searching, sorting and iterating are some of the fundamental operations required when using a list. Searching refers to finding one or more objects in the list that match a given condition. In this article, we look at some methods for searching a list in java.
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Learn how to sort a List in java. Use Java 8 Lambdas to compose sort conditions.
“You can only be afraid of what you think you know.”
― Jiddu Krishnamurti
Sorting a list is a very common requirement when programming in java. Out of the box, java provides for sorting using a performant algorithm so there is no need to roll your own algo for the purpose. In this article, we demonstrate how to sort a list in java.
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Introduction to Sorting Dictionaries in Python
Dictionaries in python are unsorted. They are stored by the hash value of the key, and this allows for fast lookup. In this article, we show a couple of ways in which dictionaries can be sorted.
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Python supports sets which are a collection of unique elements and provide operations for computing set union, intersection and difference.
“The world is a book and those who do not travel read only one page.”
― Augustine of Hippo
A set is a collection of unique elements. A common use is to eliminate duplicate elements from a list. In addition, it supports set operations like union intersection and difference.
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Learn how to use Python Scrapy to Extract information from Websites.
“When life gives you lemons, chunk it right back.”
― Bill Watterson
Scrapy is a python-based web crawler which can be used to extract information from websites. It is fast, simple and can navigate pages just like a browser can.
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Learn how to list contents of a directory from python. Also, easily find and process files matching conditions from your python program.
“If at first you don’t succeed, destroy all evidence that you tried.”
― Steven Wright
There are several methods to list a directory in python. In this article we present a few of these along with the caveats for each.
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Learn how to build regular expression patterns for parsing phone numbers, emails, etc.
Regular Expressions provide a powerful method to handle parsing tasks while handling texts. Whether the problem is a simple search for a pattern, or splitting a string into components, regular expressions are widely used today.
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