This topic is about Java 16 – Pattern Matching for instanceof.
Java 16 introduces instanceof operator to have type test pattern as is a preview feature. Type test pattern has a predicate to specify a type with a single binding variable. It continues to be a preview feature in Java 15 as well. With Java 16, this feature is now a part of standard delivery.
Syntax
if (person instanceof Employee e) {
return e.getEmployeeId();
}
Example
Consider the following example:
ApiTester.java
public class APITester {
public static void main(String[] args) {
Person manager = new Manager(23, "Robert");
manager.name = "Robert";
System.out.println(getId(manager));
}
public static int getId(Person person) {
if (person instanceof Employee e) {
return e.getEmployeeId();
}
else if (person instanceof Manager m) {
return m.getManagerId();
}
return -1;
}
}
abstract class Person {
String name;
String getName() {
return name;
}
}
final class Employee extends Person {
String name;
int id;
Employee(int id, String name){
this.id = id;
this.name = name;
}
int getEmployeeId() {
return id;
}
}
final class Manager extends Person {
int id;
Manager(int id, String name){
this.id = id;
this.name = name;
}
int getManagerId() {
return id;
}
}
Compile and Run the program
$javac APITester.java $java APITester
Output
23
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