Process handling classes and related API have been introduced in Java 9. We can use the ProcessHandle interface and related methods to get pid and information about other related processes. We need to get all children of a process, then use java.lang.ProcessHandle.children() method. This method returns a stream, typically a process that has no children.In the below example, we can get the first process and retrieve its children's process information.Exampleimport java.util.stream.Stream; import java.util.Optional; public class ChilderenProcessTest {    public static void main(String args[]) throws InterruptedException {       System.out.println("---------------------------");       System.out.println("Children Processes:");       Optional processHandle = ... Read More

In Java 9, Process API supports an easy way to get much information about a process. ProcessHandle interface can identify and provide the control of native processes and method to check processes liveness and destroy the processes whereas ProcessHandle.Info interface can give an Information snapshot of a process. We need to destroy a process by using the destroy() method of the ProcessHandle interface.In the below example, we need to terminate a process by using the ProcessHandle interface.Exampleimport java.io.File; import java.io.IOException; import java.util.Objects; public class DestroyProcessTest {    public static void main(String[] args) throws InterruptedException {       System.out.println("---------------------------");       ... Read More

In Java 9, the ofInstant() method has introduced for conversion. It is a static method of LocalDate, LocalTime, and LocalDateTime classes. This method converts java.time.Instant object to LocalDate that requires a time zone in the form of java.time.ZoneId.Syntaxpublic static LocalTime ofInstant(Instant instant, ZoneId zone) public static LocalDate ofInstant(Instant instant, ZoneId zone) public static LocalDateTime ofInstant(Instant instant, ZoneId zone)Exampleimport java.time.LocalDate; import java.time.LocalTime; import java.time.LocalDateTime; import java.time.Instant; import java.time.ZoneId; public class OfInstantMethodTest {    public static void main(String args[]) { Instant instant = Instant.parse("2020-02-05T02:35:15.245Z"); System.out.println("Instant: " + instant); ... Read More

In Java 9, the LocalDate class provides the toEpochSecond() method to convert local date into epoch seconds. The toEpochSecond() method converts the LocalDate to a number of seconds since the epoch 1970-01-01T00:00:00Z. The LocalDate can be combined with a given time and zone offset to calculate seconds starting from 1970-01-01T00:00:00Z.Syntaxpublic long toEpochSecond(LocalTime time, ZoneOffset offset)Exampleimport java.time.LocalDate; import java.time.LocalTime; import java.time.ZoneOffset; public class ToEpochSecondMethodTest {    public static void main(String args[]) {       LocalDate date = LocalDate.now();       LocalTime time = LocalTime.now();       System.out.println("LocalDate toEpochSecond : " + date.toEpochSecond(time, ZoneOffset.of("Z")));       ... Read More

Internationalization enhancements in Java 9 include Unicode 8.0, UTF-8 properties files and enabling CLDR locale data by default. Java 9 supports up to Unicode 8.0 standards with 10, 555 characters, 29 scripts, and 42 blocks.In Java 9, the properties files are loaded in UTF-8 encoding. By default, reading an input stream throws MalformedInputException or UnmappableCharacterException. In this case, PropertyResourceBundle instance reset to a state before the exception, re-reads the input stream in ISO-8859-1, and continues reading.If PropertyResourceBundle.encoding has set to either ISO-8859-1 or UTF-8, then PropertyResourceBundle instance read an input stream in that encoding, and throw an exception if encountering an invalid sequence. The system property read ... Read More

Java 9 introduced StackWalker API as an alternative to Thread.getStackTrace() or Throwable.getStackTrace() and SecurityManager.getClassContext(). This API targets a mechanism to traverse and materialize required stack frames allowing efficient lazy access to additional stack frames when required.If we need to access each stack element of an exception stack trace, then we can use the getStackTrace() method of Throwable class. It returns an array of StackTraceElement.Exampleimport java.util.*; // Test1 class class Test1 {    public void test() throws Exception {       Test2 test2 = new Test2();       test2.test();    } } // Test2 class class Test2 {    public void test() ... Read More

In Java 9, a new method added to the Collectors class: flatMapping(). It is similar to the Collectors.mapping() method in which the flatMapping() method allows us to handle nested collections. The Collectors.flatMapping() method takes a function to be applied to input elements and a collector to accumulate the elements passed through the function. Unlike the Collectors.mapping() method, the Collectors.flatMapping() method deals with a stream of elements that allows us to get rid of unnecessary intermediary collections.Syntaxpublic static Collector flatMapping(Function

Collectors class is an essential part of the Stream API. In Java 9, a new method: filtering() added to the Collectors class. The Collectors.filtering() method can be used for filtering elements in a stream. It is similar to the filter() method on streams. The filter() method processes the values before they have grouped whereas the filtering() method can be used nicely with the Collectors.groupingBy() method to group the values before the filtering step takes place.Syntaxpublic static Collector filtering(Predicate

JShell is a command-line tool that allows us to enter Java statements (simple statements, compound statements, or even full methods and classes), evaluates it and prints the result.Forward references are commands that refer to methods, variables, or classes that don't exist in any code we have typed in JShell. As code entered and evaluated sequentially in JShell, these forward references have temporarily unresolved. JShell supports forward references in method bodies, return types, parameter types, variable types, and within a class.In the below code snippet, created a method forwardReference() in Jshell. This method can't be invoked until the variable is declared. If we are trying to attempt to call this method, it throws a ... Read More

JShell is an interactive tool introduced since Java 9. It is Java's first official REPL tool to create a simple programming environment in the command-line that reads the user's inputs, evaluates it, and prints the result.We can able to create a new JShell instance programmatically in Java language. JShell and its associated APIs can be found under jdk.jshell package. we can get a new instance for JShell by using the static method: create() of JShell class. The eval() method of JShell class used to add an expression to JShell instance. It returns a list of events triggered by the evaluation. It is exactly one ... Read More