What are New Features in Java 12
June 20, 2021
1. JDK 12 supports Unicode 11 that includes 684 new characters, 11 new blocks and 7 new scripts.
2. On Linux platform, now we can assign
POSIX_SPAWN to following Java property.
jdk.lang.Process.launchMechanism = POSIX_SPAWN
POSIX_SPAWN is used for spawning child processes. The default launch mechanism on Linux is unchanged i.e. VFORK.
3. In JDK 12, a new package
java.lang.invoke.constant has been added that introduces an API to model nominal descriptions of class file and run-time artifacts.
4. In JDK 12, the
NumberFormat has been added with new support to format numbers in its compact format. Compact number formatting is the representation of a number in short or human readable form. For example, for the Locale.UK, the compact format for 1000 is 1k and for 1000000, it is 1M.
NumberFormat fmt = NumberFormat.getCompactNumberInstance(Locale.UK, NumberFormat.Style.SHORT); String result = fmt.format(1000); //1K System.out.println(result); result = fmt.format(1000000); //1M System.out.println(result);
6. In JDK 12, Z Garbage Collector supports class unloading concurrently. This feature is enabled by default but can be disabled using command line option
-XX:-ClassUnloading .
7. Now old generation of Java Heap can be allocated on alternate memory devices such as NVDIMM memory. NVDIMM is a RAM for computers. It is a non-volatile dual in-line memory module (NVDIMM) that retains its contents even when electrical power is removed. To enable this feature i.e. allocation of old generation of Java Heap on NVDIMM, use the command
-XX:AllocateOldGenAt=<path>. Once enabled, the young generation objects are placed in DRAM only and old generation objects are stored in NVDIMM. DRAM is Dynamic RAM. At any point the size of heap specified by -Xmx will be greater than the total memory committed in DRAM and NVDIMM.
8. A fix is done for OS detection to identify Windows Server 2019 correctly. Prior to this, fix Windows Server 2019 was recognized as Windows Server 2016 and hence we get incorrect values in
os.name property and hs_err_pid file.
9. A command line flag
-XX:+ExtensiveErrorReports has been added to produce extensive report related to crash as reported in the hs_err<pid>.log file.
10. Now we can provide "disallow" and "allow" token options to the
java.security.manager system property. When we assign "disallow" at the start of JVM, security manager is not set and we cannot use System.setSecurityManager. This will increase the run-time performance for the applications that never set a security manager.
11. A new
-groupname option has been added to keytool -genkeypair so that a user can specify a named group when generating a key pair.
12. 4 new Java Flight Recorder (JFR) security events have been added to the security library area. That are jdk.SecurityPropertyModification, jdk.TLSHandshake, jdk.X509Validation and jdk.X509Certificate .
13. New system and security properties have been added to enable users to customize the generation of PKCS #12 keystores.
14. New TLS cipher suites using the ChaCha20-Poly1305 algorithm have been added to JSSE. These cipher suites are enabled by default.
15. The
dns_canonicalize_hostname flag in the krb5.conf configuration file is now supported by the JDK Kerberos implementation.
16. In Java 12,
switch statement has been enhanced to use as expression as preview feature. Now we can use switch as statement as well as expression.
Find the sample code to use
switch as expression.
int day = 2;
switch (day) {
case 1 -> System.out.println("Monday");
case 2 -> System.out.println("Tuesday");
case 3 -> System.out.println("Wednesday");
}
