Hello guys, if you wonder how to remove duplicates from Stream in Java, don't worry. You can use the Stream.distinct() method to remove duplicates from a Stream in Java 8 and beyond. The distinct() method behaves like the distinct clause of SQL, which eliminates duplicate rows from the result set. The distinct() is also a standard method, which means it will return a new Stream without duplicates, which can be used for further processing. Like other methods of Stream class, I mean, map(), flatmap(), or filter(), distinct() is also lazy, and it will not remove duplicate elements until you call a terminal method on Streams like collect or forEach().
5 Examples of map() and flatMap() in Java 8 Stream
The map() and flatMap() are prince and princess of functional programming in Java. They are two powerful methods of Stream API which I believe every Java developer should be aware of and should also master it. You can use map() and flatMap() for data transformation, dealing with database operations where you need to convert one object to another while saving or reading from database. You can also use them for parsing and formatting as well as when you want to remove boiler plate code and make your data pipeline concise. The map() function is used in functional programming to transform each element of Stream into another element.
Java 8 Stream.filter() example Example with Null and Empty String
The filter() is a method on Stream class, which accepts a Predicate (a functional interface with a method which return boolean) and returns a stream consisting of the elements of this stream that match the given predicate. For example, if stream is obtained from a list containing "SONY", "APPLE" and "GOOGLE" and predicate is elements with length greater than 4, then filter will return another stream containing only APPLE and GOOGLE, leaving SONY out because its length is not greater than 4. Java 8 provides advanced filtering capability using lambdas and predicates.
Top 5 Functional Interface Every Java Developer Should Learn
Hello guys, functional interface in Java are an important concept but not many developer pay enough attention to them. They learn lambda and method reference but the functional interface from java.util.function package. While its not really possible to learn all the functional interfaces on that package but you can learn a few more commonly used ones like Predicate, Supplier, Consumer etc and that's what you will learn in this article. But, before we get to the top 5 functional interfaces that every Java developer should learn, let me tell you a bit about what Java really is.
3 Examples of flatMap() of Stream in Java
Hello guys, if you are doing Java development then you must have come across the flatMap() method on Stream and Optional Class. The flatMap() method is extension of map() function as it does both flattening and mapping (or transformation) instead of just transformation done by map() method. I have explained the difference between map() and flatMap() earlier in detail, but just to revise, let's revisit it. If you have a list of String e.g. {"credit", "debit", "master", "visa"} then you can use the map() method to get a list of integer where each value is length of corresponding String e.g. list.stream().map(s -> s.length()) will produce {6, 5, 6, 4}. This is called transformation because you have transformed an stream of String to a Stream of integer.
10 Examples of Collectors + Stream in Java 8 - groupingBy(), toList(), toMap()
As the name suggests, the Collectors class is used to collect elements of a Stream into Collection. It acts as a bridge between Stream and Collection, and you can use it to convert a Stream into different types of collections like List, Set, Map in Java using Collectors' toList(), toSet(), and toMap() method. Btw, Collector is not just limited to collection stream pipeline results into various collection class, it even provides functionalities to join String, group by, partition by, and several other reduction operators to return a meaningful result. It's often used along with the collect() method of Stream class which accepts Collectors. In this article, you will learn how to effectively use java.util.stream.Collectors in Java by following some hands-on examples.
How to use Spliterator in Java 8 - Example Tutorial
Hello friends, we are here today again on the journey of Java. And today, we are gonna learn about SplitIterator class from Stream package that may not be used in your day-to-day life but can be very useful to know as Java internally does use this with both normal streams and parallel streams. As always, let’s take an example of a situation. I will present you with a situation and you guys can think about it. So, let’s say we have an array with 50k records in it. Now, these all records need to be modified, let’s say they are strings and we need to append the string with a name. Now, traversing the array sequentially would be time-consuming. Any innovative ideas my friends?
How to Convert Stream to List, Set, and Collection in Java 8? Example Tutorial
Hello guys, if you are wondering how to convert a Stream to List, Set, Map, or any other Collection class in Java then you have come to the right place. Earlier, I have shared best Stream and Collection courses, and books as well as many Stream tutorials and in this article, I will tell you how exactly you can use Collectors to convert a Stream to List, Set, Map, or any other Collection class in Java. if you are following Java releases then you know that introduction of the Stream class is one of the most important addition in Java 8 as it makes processing bulk data really easy. Since data is the core part of any application and probably is the most important thing now than ever, a good knowledge of how to use Stream class effectively is important like how to work between Collections and Stream classes.
How to use Stream allMatch() and anyMatch() function in Java? Example Tutorial
Hello friends, we all know how streams are super important for our day-to-day needs in Java programming and coding nowadays. It allows us to filter data in memory in a declarative way, it also allows us to transform objects as well create a complex Stream pipeline to represent our business logic in a declarative fashion. But, do we know all the stream functionalities? Of course not. Earlier, we have seen examples of filter(), map, flatMap, and findFirst() method and today we will learn two of the most important stream functions anyMatch() and allMatch(). So what’s the wait? Let's start!
How to use Stream findFirst and findAny function in Java? Example Tutorial
Hello friends, here we are again on the journey of Java excited and eager to find the next stop of knowledge. But do not worry my friends, continuing the java stream series further, today we will deep dive into two other functions of streams that are equally important and interesting. Let me start by providing a situation that you guys can analyze and then we will discuss it. Let’s say you have data coming into your code through an API call. Now, you have no idea what the stream of data would be but you want the first element present in it. So, stream provides a function for the same. Let’s see what it is and how it is written.
Java 8 Predicate and Lambda Expression Example
Hello guys, if you want to learn about Predicates in Java 8 and looking for examples then you have come to the right place. In the past, I have explained key Java 8 concepts and classes like Stream, Optional, Collectors etc and we have seen how to use those functional methods like map, filter, and flatmap and in this article, I will show you how to use Predicates in Java 8 with Lambda expression. If you don't know Predicate is a functional interface in Java. A functional interface is nothing but a function with one abstract method or annotated by @FunctionalInterface annotation. Predicate is a functional interface with a function which accepts an object and return Boolean.
3 Examples to convert a Map to List in Java 8 - Example Tutorial
Hello guys, when you convert a Map to List in Java 8 or before, you have three choices like you can get a list of keys from Map, a List of values from Map, or a List of entries from Map, which encapsulates both keys and values. The API doesn't provide these methods because Map doesn't guarantee any order and the List interface guarantees ordering, like insertion order. Hence, JDK API provides an equivalent method to convert a Map to Set, like keySet() will return a set of keys and entrySet() will return a set of entries.
4 Examples of Stream.collect() method in Java 8
Hello guys, you may know that Java 8 brought Stream API which supports a lot of functional programming operations like filter, map, flatMap, reduce, and collect. In this article, you will learn about the collect() method. The collect() method of Stream class can be used to accumulate elements of any Stream into a Collection. In Java 8, you will often write code that converts a Collection like a List or Set to Stream and then applies some logic using functional programming methods like the filter, map, flatMap and then converts the result back to the Collection like a List, Set, Map, or ConcurrentMap in Java.
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