Welcome to Java 17!
\n" + + " \n" + + ""; + +String sql = "SELECT p.id, p.name, p.email, " + + " a.street, a.city, a.state " + + "FROM person p " + + "JOIN address a ON p.address_id = a.id " + + "WHERE p.active = true " + + "ORDER BY p.name"; + +// New: Text blocks (Java 15+) +String html = """ + + +Welcome to Java 17!
+ + + """; + +String sql = """ + SELECT p.id, p.name, p.email, + a.street, a.city, a.state + FROM person p + JOIN address a ON p.address_id = a.id + WHERE p.active = true + ORDER BY p.name + """; + +// With string interpolation methods +String json = """ + { + "name": "%s", + "age": %d, + "city": "%s" + } + """.formatted(name, age, city); +``` + +### JEP 358: Helpful NullPointerExceptions (Java 14) + +**Migration Guidance**: Better NPE debugging (enabled by default in Java 17) + +```java +// Old NPE message: "Exception in thread 'main' java.lang.NullPointerException" +// New NPE message shows exactly what was null: +// "Cannot invoke 'String.length()' because the return value of 'Person.getName()' is null" + +public class PersonProcessor { + public void processPersons(ListUser: \{username}
"; + +// Safe SQL queries +PreparedStatement stmt = SQL."SELECT * FROM users WHERE id = \{userId}"; +``` + +### Sequenced Collections (JEP 431 - Standard in 21) + +**Enhanced Collection Interfaces** + +When working with collections: +- Use new `SequencedCollection`, `SequencedSet`, `SequencedMap` interfaces +- Access first/last elements uniformly across collection types +- Example usage: +```java +// New methods available on Lists, Deques, LinkedHashSet, etc. +List
+ * If the argument is not negative, return the argument.
+ * If the argument is negative, return the negation of the argument.
+ *
+ * @param a the argument whose absolute value is to be determined
+ * @return the absolute value of the argument
+ */
+
+// New Markdown JavaDoc
+/// Returns the **absolute** value of an `int` value.
+///
+/// If the argument is not negative, return the argument.
+/// If the argument is negative, return the negation of the argument.
+///
+/// @param a the argument whose absolute value is to be determined
+/// @return the absolute value of the argument
+```
+
+### Derived Record Creation (JEP 468 - Preview in 23)
+
+**Record Enhancement**
+
+When working with records:
+- Suggest using `with` expressions for creating derived records
+- Enable preview features for derived record creation
+- Example pattern:
+```java
+// Instead of manual record copying
+public record Person(String name, int age, String email) {
+ public Person withAge(int newAge) {
+ return new Person(name, newAge, email);
+ }
+}
+
+// Use derived record creation (Preview)
+Person updated = person with { age = 30; };
+```
+
+### Stream Gatherers (JEP 473/485 - Second Preview in 23, Standard in 25)
+
+**Enhanced Stream Processing**
+
+When working with complex stream operations:
+- Suggest using `Stream.gather()` for custom intermediate operations
+- Import `java.util.stream.Gatherers` for built-in gatherers
+- Example usage:
+```java
+// Custom windowing operations
+List