Java 14 reached General Availability on 17 March 2020, download Java 14 here.
Java 14 features.
Before Java 14, we use instanceof-and-cast
to check the object’s type and cast to a variable.
if (obj instanceof String) { // instanceof String s = (String) obj; // cast if("jdk14".equalsIgnoreCase(s)){ //... } }else { System.out.println("not a string"); }
Now Java 14, we can refactor above code like this:
if (obj instanceof String s) { // instanceof, cast and bind variable in one line. if("jdk4".equalsIgnoreCase(s)){ //... } }else { System.out.println("not a string"); }
if obj
is an instance of String
, then it is cast to String
and assigned to the binding variable s
.
New jpackage
tool to package a Java application into a platform-specific package.
For example, package the JAR
file into an exe
file on Windows.
P.S Update jpackage
example here
New NUMA-aware memory allocation mode, improves the G1 performance on large machines. Add +XX:+UseNUMA
option to enable it.
Improved the existing JFR to support event streaming, it means now we can stream the JFR events in real-time, without the need to dump the recorded events to disk and parse it manually.
The JDK Flight Recorder (JFR) is a tool for collecting diagnostic and profiling data about a running Java application. Normally, we start a recording, stop it, dump the recorded events to disk for parsing, it works well for profiling, analysis, or debugging.
Related JEP 328: Flight Recorder
P.S Update JFR Event Streaming example here_
Improved FileChannel
API to create MappedByteBuffer
that access to non-volatile memory (NVM) – a memory that can retrieve stored data even after having been power cycled. For example, this feature ensures that any changes which might still be in the cache are written back to memory.
P.S Only Linux/x64 and Linux/AArch64 OS support this!
Improved the description of NullPointerExceptions
by telling which variable was null. Add -XX:+ShowCodeDetailsInExceptionMessages
option to enable this feature.
A simple Java file that throws an NullPointerException
.
Test.java
import java.util.Locale; public class Test { public static void main(String[] args) { String input = null; String result = showUpperCase(input); // NullPointerException System.out.println(result); } public static String showUpperCase(String str){ return str.toUpperCase(Locale.US); } }
Before Java 14.
$ /usr/lib/jvm/jdk-14/bin/java Test Exception in thread "main" java.lang.NullPointerException at Test.showUpperCase(Test.java:15) at Test.main(Test.java:9)
Java 14 with -XX:+ShowCodeDetailsInExceptionMessages
option.
$ /usr/lib/jvm/jdk-14/bin/java -XX:+ShowCodeDetailsInExceptionMessages Test Exception in thread "main" java.lang.NullPointerException: Cannot invoke "String.toUpperCase(java.util.Locale)" because "<parameter1>" is null at Test.showUpperCase(Test.java:15) at Test.main(Test.java:9)
P.S Please enable this feature by default