java anomymous code block

In Java, an anonymous code block is a block of code that is defined and executed without a name. Anonymous code blocks are typically used to define short pieces of code that are used only once and are not meant to be reused.

There are two main types of anonymous code blocks in Java: anonymous inner classes and lambda expressions.

Anonymous Inner Classes

An anonymous inner class is a type of inner class that does not have a name. It is defined and used in a single location, and cannot be used elsewhere in the code.

Here is an example of how to use an anonymous inner class to create a thread:

new Thread(new Runnable() {
    public void run() {
        // Code to be executed in the thread
    }
}).start();

In this example, the anonymous inner class implements the Runnable interface and defines the run() method, which will be executed when the thread is started.

Lambda Expressions

A lambda expression is a concise way to define a block of code as a function. It allows you to specify a block of code as an argument to a method, or to assign it to a variable.

Here is an example of how to use a lambda expression to define a code block that prints a message:

Runnable r = () -> System.out.println("Hello, world!");

In this example, the lambda expression defines a code block that takes no arguments and returns no value. The code block is assigned to the Runnable variable r, and can be executed by calling the run() method on r.

Anonymous code blocks are often used to define small pieces of code that are used only once and are not meant to be reused. They can be useful for defining simple behavior or for creating concise and readable code. However, they should be used with caution, as they can make the code more difficult to understand if overused.