Java’s agility is a major factor in its success. Since its first 1.0 release, Java has continuously changed to reflect changes in both the programming environment and programmers’ practices. Most significantly, it has contributed to the development of trends rather from merely following them. One of the main reasons Java has been and will continue to be so successful is its capacity to adapt to the quick pace of change in the computer industry.

Previously, major Java versions were often two or more years between. However, since the release of JDK 9, the interval between major Java versions has been reduced. Today, it is assumed that a major release will take place on a fixed timetable, with just six months between such releases.

key features that have been added to the Java language

Modules

Modules, which allow you to declare the connection and dependencies of the code that makes up an application, were the main new JDK 9 feature. Modules can provide an additional level to Java’s access control capabilities. The addition of modules resulted in the addition of a new syntactic element and numerous keywords to Java. In addition, the JDK now includes a tool called jlink, which allows a programmer to construct a run-time image of an application that contains only the essential modules. JMOD, a new file type, was created. Modules have a significant impact on the API library since library packages are now divided into modules beginning with JDK 9.

Local Variable Type inference

With local variable type inference, the type of a local variable can now be inferred from the type of its initializer rather than being explicitly declared. Java’s context-sensitive keyword var was created to accommodate this new functionality. When a variable’s type can be inferred from its initializer, type inference can help to reduce code duplication. It can also help to simplify declarations when the type is difficult to identify or cannot be clearly indicated.

Using var in lambda expressions

Using var modifiers can be added to local variables and lambda formals without losing brevity, which helps in uniformity. A type annotation, for example, is a common modifier. We cannot use such annotations unless the types are specified.

(@Nonnull var s1, @Nullable var s2) -> s1 + s2

Enhancements to switch

The switch expression is the modification to switch that will have the most effect. In essence, a switch expression is a switch that returns a value. As a result, it possesses all the features of a conventional switch statement as well as the capacity to generate a result. The switch expression is one of Java’s more significant recent additions because of its new capabilities. The new yield statement is one approach to deliver the value of a switch expression.

Text blocks

A text block is a new kind of literal that is comprised of a sequence of characters that can occupy more than one line. A text block reduces the tedium programmers often face when creating long string literals because newline characters can be used in a text block without the need for the \n escape sequence. Furthermore, tab and double quote characters can also be entered directly, without using an escape sequence, and the indentation of a multiline string can be preserved. Although text blocks may, at first, seem to be a relatively small addition to Java, they may well become one of the most popular features.

Records

One of the central motivations for records is the reduction of the effort required to create a class whose primary purpose is to organize two or more values into a single unit. Although it has always been possible to use class for this purpose, doing so can entail writing a number of lines of code for constructors, getter methods, and possibly (depending on use) overriding one or more of the methods inherited from Object. As you will see, by creating a data aggregate by using record, these elements are handled automatically for you, greatly simplifying your code.

Another reason for the addition of records is to enable a program to clearly indicate that the intended purpose of a class is to hold a grouping of data, rather than act as a full-featured class. Because of these advantages, records are a much welcomed addition to Java.

Patterns in instanceof

instanceof evaluates to true if an object is of a specified type, or can be cast to that type. Beginning with JDK 16, a second form of the instanceof operator has been added to Java that supports the new pattern matching feature. In general terms, pattern matching defines a mechanism that determines if a value fits a general form. As it relates to instanceof, pattern matching is used to test the type of a value (which must be a reference type) against a specified type. This kind of pattern is called a type pattern. If the pattern matches, a pattern variable will receive a reference to the object matched by the pattern.

Sealed classes and interfaces

Beginning with JDK 17, it is possible to declare a class that can be inherited by only specific subclasses. Such a class is called sealed. Prior to the advent of sealed classes, inheritance was an “all or nothing” situation. A class could either be extended by any subclass or marked as final, which prevented its inheritance entirely. Sealed classes fall between these two extremes because they enable you to specify precisely what subclasses a superclass will allow.

In similar fashion, it is also possible to declare a sealed interface in which you specify only those classes that implement the interface and/or those interfaces that extend the sealed interface. Together, sealed classes and interfaces give you significantly greater control over inheritance, which can be especially important when designing class libraries. read more

New Stream Methods

• Stream.mapMulti()
• Stream.toList()

conclusion

These new features, taken together, radically broaden the ways in which you may develop and deploy solutions.