Sean Robertson

Sean Robertson

1548127618

Generic Filter for enum

Following is my class

public final class Test {
enum Animal {DOG,CAT};
enum COLOR {RED,YELLOW};

class Meaningless {
String animal,color;
}
public void filter(List<Meaningless> meaninglesses){
meaninglesses.stream()
.filter(meaningless -> {
try {
Animal.valueOf(meaningless.animal);
return true;
}catch(Exception e){
return false;
}
})
.filter(meaningless -> {
try {
COLOR.valueOf(meaningless.color);
return true;
}catch(Exception e){
return false;
}
})
.collect(Collectors.toList());
}

}

The 2 iterations of filter methods essentially filters out the invalid enum types. How can I remove the code duplication from this ? The check should be generic enough so that I dont have to change the isValidEnum when there is a new enum introduced.

Ideally I would like to do something like

 meaninglesses.stream()
.filter(meaningless -> isValidEnum(meaningless.animal,Animal.class))
.filter(meaningless -> isValidEnum(meaningless.color,COLOR.class))


#java

What is GEEK

Buddha Community

Charles Cooper

1548232656

The following utility method should do the trick here,

public static <E extends Enum<E>> boolean validateEnum(Class<E> clazz, String s) {
    return EnumSet.allOf(clazz).stream().anyMatch(e -> e.name().equals(s));
}

And here’s how your client code looks in practice,

boolean isValid = validateEnum(Animal.class, "DOG");

Finally, putting it back to your context, it should be something like this.

meaninglesses.stream()
    .filter(meaningless -> validateEnum(Animal.class, meaningless.animal))
    .filter(meaningless -> validateEnum(COLOR.class, meaningless.color))
    .collect(Collectors.toList());

Guide to Understanding Generics in Java

Introduction

Java is a type-safe programming language. Type safety ensures a layer of validity and robustness in a programming language. It is a key part of Java’s security to ensure that operations done on an object are only performed if the type of the object supports it.

Type safety dramatically reduces the number of programming errors that might occur during runtime, involving all kinds of errors linked to type mismatches. Instead, these types of errors are caught during compile-time which is much better than catching errors during runtime, allowing developers to have less unexpected and unplanned trips to the good old debugger.

Type safety is also interchangeably called strong typing.

Java Generics is a solution designed to reinforce the type safety that Java was designed to have. Generics allow types to be parameterized onto methods and classes and introduces a new layer of abstraction for formal parameters. This will be explained in detail later on.

There are many advantages of using generics in Java. Implementing generics into your code can greatly improve its overall quality by preventing unprecedented runtime errors involving data types and typecasting.

This guide will demonstrate the declaration, implementation, use-cases, and benefits of generics in Java.

#java #guide to understanding generics in java #generics #generics in java #guide to understanding generics in java

Jeromy  Lowe

Jeromy Lowe

1598736540

Generics in Kotlin

Generics is a facility for generic programming, allowing classes, interfaces and methods to operate on various types of objects. It basically allows a type to be a parameter to methods, classes and interfaces.

Generics removes the need to typecast by restricting the accepted types and hence guaranteeing run time type safety.

Type Parameters
Type parameters are used to implement generics. The type parameters are placeholders for the actual type to be used with the classes, interfaces or methods.

#variance #generics #generics-in-kotlin #generics-programming #invariance

Twig filters: useful filters, create own custom filter in Symfony 4

This videos goes over Most useful twig filters that i use most of the time (not all of them), and also how to create your own filter to extend the functionalities of twig.

This video includes the following filters:

  • Format
  • Striptags
  • Filter
  • Reduce
  • Date
  • Date_modify
  • Batch
  • How to create your own custom filter in twig for Symfony 4.

#filters #symfony 4 #twig filters

Hudson  Larkin

Hudson Larkin

1600195500

C++ Enum Example | Enumeration (or enum) in C++

C++ Enum (Enumeration) is a user-defined datatype where we specify the set of values for a variable, and the variable can only take one out of a small set of possible values.

C++ Enum Example

An enumeration is the distinct type whose value is restricted to the range of values (see below for details), which may include a several explicitly named constants (“enumerators“). The values of the constants are the values of an integral type known as an underlying type of the enumeration.

Keyword and Syntax

If we want to declare an enumeration, we use the keyword enum.

The syntax is the following.

enum enum_name {const1, const2, const3,..., const-n};

Example:

enum months {Jan, Feb, March, April, May};

Here, enum name is month and Jan, Feb, March… are the type of months.

#c++ #enum #c++ enum

Fannie  Zemlak

Fannie Zemlak

1603108800

Understanding Search Engine Filtering of Customer Reviews

In the digital era, you see people dropping reviews online as customers. We can even see companies seeking a platform to provide them with online reviews to boost their business. You might have heard or read about online review filters and how it might have caused frustrations or confusion. Understanding search engine filtering of customer reviews can help you minimize this vagueness.

Why do we need to filter reviews?

We can see an obvious sky-rocket in searching among people in the past decade. People depend on their search results and the reviews they read about a particular thing.

Reviews can be an excellent scale to measure the popularity of a business. It also gives real-life experience to searchers for a specific kind of business or service or etc.

If reviews are so cool and helpful, why do we need an algorithm to filter them?

Since the development of technology, you see that robots also can drop reviews. Some companies even hire people who even might not be customers to give them good reviews. We can also see companies dropping reviews for themselves. So, there you have the reasons for the filtering of customer reviews. For instance, on social media platforms, Instagram uses the filtering algorithm for cleaning the purchased followers.

How does the filtering work?

The specific details of these kinds of algorithms have not been revealed, but the general sense of the mechanism is out there, which is the backbone of most filtering algorithms. Filtering gets triggered when one or more of the following happens:

• Sudden increase in the number of reviews in a short period of time

• Abnormal usage of keywords

• Overuse of complimenting adjectives or swearwords

• Link usage in the reviews

Some of the more advanced and cutting-edge filters do not only stop at the aforementioned points. They also check the characteristics of users, such as:

• The IP addresses

• Number of reviews written by a single user on a website

• How often a user leaves reviews on a particular site

Considering the points above, one could understand how probable it is for the fake reviewers to get stuck in the filter, all thanks to the smart algorithm.

#online-reviews #algorithms #spam-filter #web-filtering-software #content-filtering #vpn-review #search-engine #search-engines