Java 19 New Features Introduction & Examples

Java 19 includes a number of new features and improvements, including support for pattern matching, improved garbage collection, and support for records and sealed classes. It also includes support for the Z Garbage Collector, which is designed to reduce application pauses and improve overall performance. Additionally, Java 19 includes support for the new Java Flight Recorder, which allows developers to collect and analyze data about their applications.

Table of Contents

1. What Is Java 19 Pattern Matching & Examples.

Java 19’s pattern matching feature allows developers to use a concise syntax to match data against a pattern.

This feature can be used to simplify code and make it easier to read.
It also allows developers to use patterns to match against objects, making it easier to extract data from them.
Additionally, pattern matching can be used to simplify switch statements and reduce the amount of code needed to perform certain operations.

Below is the java 19 pattern matching example code.

// Match a String against a pattern
String input = "Hello World";
if (input instanceof String s && s.startsWith("Hello")) {
    System.out.println("Input starts with 'Hello'");
}
// Match an Integer against a pattern
Integer number = 42;
if (number instanceof Integer n && n > 0) {
    System.out.println("Number is greater than 0");
}

2. Java 19 Improved Garbage Collection Introduction.

Java 19 includes improved garbage collection features that are designed to reduce application pauses and improve overall performance.
The new Z Garbage Collector is designed to reduce application pauses by using a concurrent and parallel approach to garbage collection.

Additionally, Java 19 includes support for the G1 Garbage Collector, which is designed to reduce application pauses and improve overall performance.

2.1 Z Garbage Collector.

The Z Garbage Collector is a new garbage collector in Java 19 that is designed to reduce application pauses and improve overall performance.
It uses a concurrent and parallel approach to garbage collection, which allows it to collect garbage in the background while the application is running.

Additionally, the Z Garbage Collector is designed to reduce the amount of time needed to perform garbage collection, which can help improve application performance.

2.2 G1 Garbage Collector.

The Java 19 G1 Garbage Collector is a garbage collection algorithm that is part of the Java Virtual Machine.
It works by separate the heap into a number of different regions, each of which is collected independently.

The G1 Garbage collector also supports concurrent and parallel processing, as well as incremental and concurrent compaction.
This means the G1 Garbage Collector can provide improved throughput, response time, and memory usage compared to other garbage collection algorithms.
The G1 Garbage Collector can also be configured to be more aggressive in reclaiming memory, thereby increasing the overall performance of the application.

2.3 Original Garbage Collector Example Source Code.

The below code example shows how to create a new garbage collector in java.
It set the garbage collection parameters, and then run it.
The maxHeapSize parameter specifies the maximum amount of memory the garbage collector should use.

While freeHeapSize and minFreeHeapSize specify the minimum and maximum amount of free heap space that must be available for the garbage collector to complete its job.

// Create a new garbage collector
GarbageCollector gc = new GarbageCollector();

// Set the garbage collection parameters 
gc.setMaxHeapSize(2048);
gc.setFreeHeapSize(1024);
gc.setMinFreeHeapSize(512);

// Run the garbage collector
gc.run();

// Check the results to reclaim unused memory
System.out.println(gc.getUnusedMemory());

3. Java 19 Records And Sealed Classes Introduction.

Java 19 introduces the concept of records and sealed classes.
Records are a new type of class that are designed to simplify the creation of immutable data classes.

Sealed classes are a new type of class that are designed to restrict the inheritance of a class to a specific set of subclasses.
Both records and sealed classes are designed to improve the readability and maintainability of code.
An example of a record class in Java 19 is as follows.
```
public record Person(String name, int age) {

}
```

This record class defines a Person object with two fields: name and age.
The record class is immutable, meaning that the fields cannot be changed once the object is created.
An example of a sealed class in Java 19 is as follows.
```
public sealed class Animal permits Cat, Dog {

}
```

This sealed class defines an Animal class that can only be extended by the Cat and Dog classes.
This helps to ensure that the Animal class is only extended by the classes that are intended to extend it.

4. What Is Java Flight Recorder In Java 19?

Java Flight Recorder (JFR) is a profiling and event collection framework built into the Java Virtual Machine (JVM).

It allows developers to collect detailed information about the performance and behavior of their applications.
JFR was introduced in Java 11 and has been improved in Java 19 with the addition of new features such as the ability to collect data from multiple JVMs and the ability to collect data from multiple threads.

An example of using Java Flight Recorder in Java 19 is as follows.

// Create a new JFR instance
FlightRecorder recorder = FlightRecorder.newRecorder();

// Set the recording options
RecordingOptions options = new RecordingOptions()
    .duration(Duration.ofMinutes(5))
    .name("My Recording")
    .enable(JFRFeature.CPU_LOAD);

// Start the recording
recorder.start(options);

// Do some work
// ...

// Stop the recording
recorder.stop();

// Generate a report
recorder.generateReport();