Java lambda expressions list

Java lambda expressions list

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Here is the information about Java lambda expressions:

Java lambda expressions are a new feature introduced in Java 8 that allows you to write concise, one-method interfaces. They were designed to be used as replacements for traditional anonymous classes.

Here are some key points about Java lambda expressions:

Syntax:

The syntax for a Java lambda expression is as follows:

(parameters) -> { code }

Where parameters is a comma-separated list of parameter names, and { code } is the body of the lambda expression.

Example:

Here's an example of a simple lambda expression that takes two integers and returns their sum:

(int x, int y) -> { return x + y; }

Using Lambda Expressions:

Lambda expressions can be used in several contexts in Java. Some common uses include:

Collections.sort(list, (a, b) -> a.compareTo(b));

Advantages:

Java lambda expressions offer several advantages over traditional anonymous classes. Some of the key benefits include:

Example:

Here's an example of using a lambda expression with a Java stream:

List list = Arrays.asList("apple", "banana", "cherry");
list.stream().filter((s) -> s.startsWith("a")).forEach(System.out::println);

In this example, the lambda expression (s) -> s.startsWith("a") is used to filter a stream of strings.

Conclusion:

Java lambda expressions are a powerful feature that allows you to write concise and expressive code. They can be used in several contexts in Java, including method references, functional interfaces, and streams.

lambda expression in java interview questions

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Lambda expressions are a powerful feature in Java introduced in version 8 (Java SE 8). They allow you to write concise and expressive code, making your programming life easier. Here are some common lambda expression-related interview questions:

Answer: Lambda expressions enable functional programming in Java, allowing you to write small, anonymous functions that can be used as arguments to methods or returned from methods.

Example:

Runnable r = () -> System.out.println("Hello");
r.run(); // prints "Hello"

This lambda expression defines an anonymous Runnable interface, which is executed when the run() method is called.

Example:

 Comparator c = String::compareTo;
System.out.println(c.compare("hello", "world")); // prints -1

In this example, we create a lambda expression that refers to the compareTo() method of the String class. This can be useful when you need to pass an existing method as a callback.

Answer: A functional interface is an interface with a single abstract method (SAM). Lambda expressions are instances of functional interfaces that can be used to implement them.

Example:

List list = Arrays.asList("hello", "world", "lambda");
list.stream()
.filter(s -> s.length() > 4)
.collect(Collectors.toList());
// returns ["lambda"]

In this example, we use a lambda expression to filter the elements of a List based on their length.

Example:

public class Example {
public static void main(String[] args) {
Function<Integer, Integer> square = x -> x * x;
System.out.println(square.apply(4)); // prints 16
}
}

In this example, we define a higher-order function square that takes an integer as input and returns its square. We then apply the lambda expression to the value 4.

Example:

public class Example {
public static void main(String[] args) {
BiConsumer<String, Integer> biConsumer = String::concat;
biConsumer.accept("Hello, ", 25); // prints "Hello, 25"
}
}

In this example, we use a lambda expression to refer to the concat() method of the String class.

Answer: Lambda expressions are commonly used as part of Java 8's Stream API to create intermediate operations that transform data. For example, using map(), filter(), or reduce() methods on a stream to perform specific operations.

Example:

public class Example {
public static void main(String[] args) {
RecursiveFunction rf = x -> x == 0 ? 1 : Math.min(x, recursiveFunction(x - 1));
System.out.println(rf.apply(5)); // prints the smallest number that can be expressed as a sum of 2's and 5's using up to 5 iterations
}
}

In this example, we define a lambda expression that implements a recursive function to calculate the smallest number that can be expressed as a sum of 2's and 5's using up to x iterations.

These are just a few examples of lambda expressions in Java. Mastering these concepts will help you write more concise, expressive, and efficient code!