public static void main(String[] args) {\n \/\/create a BiFunction\n BiFunction<String, String, String> stringJoiner = (String a, String b) -> a + b;\n \n \/\/call the apply method\n System.out.println(stringJoiner.apply("Hello ", "World"));\n \n }<\/pre><\/div>\n\n\n\nThe code above creates a BiFunction called stringJoiner<\/code>. As you can see, the types of the arguments and the return object don’t need to be different. <\/p>\n\n\n\nRunning the code above would provide the following results:<\/p>\n\n\n\nLet’s try something less boring than just String. As you may know, a male Donkey and a female Horse went to a bar and sometime later, they will produce a Mule. However, if a female Donkey and a male Horse went to a bar, the couple would produce a Hinny!<\/p>\n\n\n\n
Let’s first create some classes to represent the animals:<\/p>\n\n\n\n
enum Gender {\n MALE,\n FEMALE\n}\nrecord Horse(String name, Gender gender) {\n}\n\nrecord Donkey(String name, Gender gender) {\n\n}\n\ninterface HorseDonkey {\n}\n\nrecord Mule(String name) implements HorseDonkey {\n @Override\n public String toString() {\n return "Mule{" +\n "name='" + name + '\\'' +\n '}';\n }\n}\n\nrecord Hinny(String name) implements HorseDonkey {\n @Override\n public String toString() {\n return "Hinny{" +\n "name='" + name + '\\'' +\n '}';\n }\n}\n<\/pre><\/div>\n\n\n\nAnd here is the BiFunction<\/p>\n\n\n\n
BiFunction<Horse, Donkey, HorseDonkey> downtownBar = (Horse horse, Donkey donkey) -> {\n if (horse.gender() == Gender.FEMALE && donkey.gender() == Gender.MALE) {\n return new Mule(horse.name() + "\\uD83D\\uDD25" + donkey.name());\n } else if (horse.gender() == Gender.MALE && donkey.gender() == Gender.FEMALE) {\n return new Hinny(horse.name() + "\\uD83D\\uDD25" + donkey.name());\n }\n\n throw new RuntimeException("Not implemented yet");\n };<\/pre><\/div>\n\n\n\nLet’s try with Jack the male horse and Jane the female Donkey.<\/p>\n\n\n\n
public static void main(String[] args) {\n\n BiFunction<Horse, Donkey, HorseDonkey> downtownBar = (Horse horse, Donkey donkey) -> {\n if (horse.gender() == Gender.FEMALE && donkey.gender() == Gender.MALE) {\n return new Mule(horse.name() + "\\uD83D\\uDD25" + donkey.name());\n } else if (horse.gender() == Gender.MALE && donkey.gender() == Gender.FEMALE) {\n return new Hinny(horse.name() + "\\uD83D\\uDD25" + donkey.name());\n }\n\n throw new RuntimeException("Not implemented yet");\n };\n\n var jack = new Horse("Jack", Gender.MALE);\n var jane = new Donkey("Jane", Gender.FEMALE);\n\n var horseDonkey = downtownBar.apply(jack, jane);\n\n System.out.println(horseDonkey);\n }<\/pre><\/div>\n\n\n\nYou can expect that the result is a Hinny:<\/p>\n\n\n\nChaining BiFunction and Function<\/h2>\n\n\n\n Imagine you need to write a function to calculate the shipping fee and tax for an order of many items. The steps are:<\/p>\n\n\n\n
\nFirst, calculate the total (without shipping and tax)<\/li>\n\n\n\n Next, calculate the total with the shipping<\/li>\n\n\n\n Finally, calculate the tax based on the total with shipping<\/li>\n<\/ol>\n\n\n\nThe BiFunction interface has a default method called andThen<\/code> that accepts a Function. You can achieve the above requirements with the following code:<\/p>\n\n\n\n\trecord CartLine(String name, int quantity, double price) {\n\t}\n public static void main(String[] args) {\n var cart = List.of(\n new CartLine("Apple", 2, 1.5),\n new CartLine("Orange", 3, 2.0),\n new CartLine("Banana", 1, 3.0)\n );\n\n var shippingRate = 0.5;\n var tax = 0.1;\n\n BiFunction<Double, Double, Double> shippingBifunction = (total, rate) -> total * (1 + rate);\n Function<Double, Double> taxFunction = (total) -> total * (1 + tax);\n\n var cartTotal = cart.stream()\n .mapToDouble(line -> line.price() * line.quantity())\n .sum();\n\n var finalTotal = shippingBifunction.andThen(taxFunction);\n\n System.out.println(finalTotal.apply(cartTotal, shippingRate));\n }<\/pre><\/div>\n\n\n\nThe andThen<\/code> method returns a BiFunction. That means you can keep calling andThen<\/code> to pass in as many Functions as you need.<\/p>\n\n\n\nRunning the code would provide the following result:<\/p>\n\n\n\nConclusion<\/h2>\n\n\n\n In this post, I’ve shown you the basic usages of the BiFunction functional interface in Java. To use this interface, you need to provide the implementation for the apply method. You can also use the andThen<\/code> method to chain subsequent functions to further process the result. <\/p>\n","protected":false},"excerpt":{"rendered":"Overview In Java, A BiFunction represents a function that accepts two arguments and returns a result. The interface has one abstract method apply and one default method andThen. The apply method is defined as follows: That means it accepts two arguments (t of type T and u of type U) and returns an object of … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":1974,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"footnotes":""},"categories":[1,4],"tags":[],"class_list":["post-1935","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-backend","category-java"],"yoast_head":"\nJava BiFunction Tutorial - datmt<\/title>\n<meta name=\"description\" content=\"Unlock the Power of Java BiFunction: Dive into our comprehensive tutorial, packed with examples and practical insights. Learn how to harness the versatility of BiFunction for efficient data processing in Java. 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