Java 14 Features

Pattern Matching for instanceof (Preview)
Packaging Tool (Incubator)
NUMA-Aware Memory Allocation for G1
JFR Event Streaming
Non-Volatile Mapped Byte Buffers
Helpful NullPointerExceptions
Records (Preview) (developer feature)
Switch Expressions (Standard) (developer feature)
Deprecate the Solaris and SPARC Ports
Remove the Concurrent Mark Sweep (CMS) Garbage Collector
ZGC on macOS
ZGC on Windows
Deprecate the ParallelScavenge + SerialOld GC Combination
Remove the Pack200 Tools and API
Text Blocks (Second Preview) (developer feature)
Foreign-Memory Access API (Incubator) (developer feature)

Pattern Matching for instanceof

Before Java 14, we were used 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("java".equalsIgnoreCase(s)){

}
}else {
System.out.println("not a string");
}

Now in Java 14

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

Packaging Tool (Incubator)
New jpackage tool to package a Java application into a platform-specific package.

Linux: deb and rpm
macOS: pkg and dmg
Windows: msi and exe
For example, package the JAR file into an exe file on Windows

Helpful NullPointerExceptions

Improved the description of NullPointerExceptions by telling which variable was null. Add -XX:+ShowCodeDetailsInExceptionMessages option to enable this feature.

A Java file that throws an NullPointerException

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.

$ D:/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

$ D:/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)

Switch Expressions (Standard)

The switch expression was a preview feature in Java 12 and Java 13; now it is officially JDK standard feature, it means from Java 14 and onward, we can return value via switch expressions without specifying the --enable-preview option.

We can use yield to return a value from a switch

private static int getValueViaYield(String mode) {
int result = switch (mode) {
case "a", "b":
yield 1;
case "c":
yield 2;
case "d", "e", "f":
// do something here...
System.out.println("Supports multi line block!");
yield 3;
default:
yield -1;
};
return result;
}

Java 14 Features

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