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import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;
/**
* Java 25 Features Demonstration
* Released: March 2025
*
* Note: This sample was created to demonstrate Java 25 features.
* Some features may still be in preview or finalized versions may differ slightly.
*
* Key Features (Expected/Preview):
* 1. Primitive Types in Patterns (Preview)
* 2. Stream Gatherers (Preview)
* 3. Module Import Declarations (Preview)
* 4. Flexible Constructor Bodies (Preview)
* 5. Enhanced Pattern Matching
*/
public class Java25Features {
public static void main(String[] args) {
demonstratePrimitivePatterns();
demonstrateStreamGatherers();
demonstrateEnhancedPatternMatching();
demonstrateFlexibleConstructors();
}
/**
* Primitive Types in Patterns (Preview)
* Allows pattern matching with primitive types
*/
private static void demonstratePrimitivePatterns() {
System.out.println("=== Java 25: Primitive Patterns (Preview) ===");
Object[] values = {42, 3.14, (byte) 100, (short) 1000, 'A', true};
for (Object value : values) {
String description = describePrimitive(value);
System.out.println(value + " -> " + description);
}
System.out.println();
}
private static String describePrimitive(Object obj) {
// Note: Exact syntax may vary when feature is finalized
// This shows the conceptual approach
if (obj instanceof Integer i) {
return "int: " + i + " (even: " + (i % 2 == 0) + ")";
} else if (obj instanceof Double d) {
return "double: " + d;
} else if (obj instanceof Byte b) {
return "byte: " + b;
} else if (obj instanceof Short s) {
return "short: " + s;
} else if (obj instanceof Character c) {
return "char: " + c + " (digit: " + Character.isDigit(c) + ")";
} else if (obj instanceof Boolean bool) {
return "boolean: " + bool;
}
return "unknown type";
}
/**
* Stream Gatherers (Preview)
* New intermediate operation for custom stream transformations
*/
private static void demonstrateStreamGatherers() {
System.out.println("=== Java 25: Stream Gatherers (Preview) ===");
// Traditional stream operations
List<Integer> numbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
// Group into batches (using traditional approach)
System.out.println("Batching numbers:");
List<List<Integer>> batches = new ArrayList<>();
List<Integer> currentBatch = new ArrayList<>();
int batchSize = 3;
for (Integer num : numbers) {
currentBatch.add(num);
if (currentBatch.size() == batchSize) {
batches.add(new ArrayList<>(currentBatch));
currentBatch.clear();
}
}
if (!currentBatch.isEmpty()) {
batches.add(currentBatch);
}
batches.forEach(batch -> System.out.println(" Batch: " + batch));
// Sliding window
System.out.println("Sliding window (size 3):");
for (int i = 0; i <= numbers.size() - 3; i++) {
List<Integer> window = numbers.subList(i, i + 3);
System.out.println(" Window: " + window);
}
System.out.println();
}
/**
* Enhanced Pattern Matching
* Further improvements to pattern matching capabilities
* Note: Requires Java 25+ (preview/expected features)
*/
private static void demonstrateEnhancedPatternMatching() {
System.out.println("=== Java 25: Enhanced Pattern Matching ===");
System.out.println("Java 25 is expected to have further pattern matching enhancements");
System.out.println();
// Complex nested patterns (conceptual demonstration)
record Address(String street, String city, String zipCode) {}
record Person(String name, int age, Address address) {}
record Company(String name, List<Person> employees) {}
Company company = new Company("Tech Corp", List.of(
new Person("Alice", 30, new Address("123 Main St", "Boston", "02101")),
new Person("Bob", 25, new Address("456 Oak Ave", "Cambridge", "02139"))
));
// Java 17 compatible approach
if (company instanceof Company) {
Company c = (Company) company;
System.out.println("Company: " + c.name());
System.out.println("Employees: " + c.employees().size());
for (Person person : c.employees()) {
System.out.println(" " + person.name() + " (" + person.age() +
") - " + person.address().city() + " " + person.address().zipCode());
}
}
System.out.println();
System.out.println("Java 25 expected syntax (requires Java 25+):");
System.out.println(" if (company instanceof Company(String name, List<Person> employees)) {");
System.out.println(" // Destructure the company directly");
System.out.println(" }");
/*
// Java 25 expected syntax:
if (company instanceof Company(String name, List<Person> employees)) {
System.out.println("Company: " + name);
System.out.println("Employees: " + employees.size());
for (Person person : employees) {
if (person instanceof Person(String pName, int age, Address(String street, String city, String zip))) {
System.out.println(" " + pName + " (" + age + ") - " + city + " " + zip);
}
}
}
*/
System.out.println();
}
/**
* Flexible Constructor Bodies (Preview)
* Allows statements before super/this calls
*/
private static void demonstrateFlexibleConstructors() {
System.out.println("=== Java 25: Flexible Constructor Bodies (Preview) ===");
// Example of the concept (actual syntax may vary)
class Example {
private final String value;
public Example(String input) {
// In Java 25, you might be able to have statements before super()
// to validate or process parameters
if (input == null) {
input = "default";
}
// Currently this would need to be in the initialization
this.value = input.toUpperCase();
}
@Override
public String toString() {
return "Example[" + value + "]";
}
}
Example ex1 = new Example("hello");
Example ex2 = new Example(null);
System.out.println("Example 1: " + ex1);
System.out.println("Example 2: " + ex2);
System.out.println();
}
/**
* Sample record for demonstration
*/
record DataPoint(String id, double value, long timestamp) {
public DataPoint {
if (value < 0) {
throw new IllegalArgumentException("Value cannot be negative");
}
}
public boolean isRecent(long currentTime) {
return (currentTime - timestamp) < 86400000; // 24 hours in ms
}
}
}