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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to filter stack frames using StackWalker API in Java 9?
StackWalker API provides a stream of information in stack traces during the execution of a program. This API requires a virtual machine to capture a snapshot of the entire stack and returns an array of elements for filtering purposes. We need to skip, drop, and limit the stack frames by using the walk() method. We can also filter a stack frame by class for getting the first matching frame, and all matching frames by using the filter() method.In the below example, we can filter a stack frame by using StackWalker API.Exampleimport java.lang.StackWalker.StackFrame; import java.util.*; import java.util.stream.*; public class StackWalkerFilterTest ...
Read MoreHow to print different stack frames using StackWalker API in Java?
Java 9 defines a StackWalker API that provides laziness and frame filtering. An object of StackWalker allows us to traverse and access stacks and contains one useful method: walk(). This method opens a StackFrame stream for the current thread, then applies the function with that StackFrame stream. We need to get StackWalker object, then use StackWalker.getInstance() method.In the below example, we can print different stack frames: all stack frames, skip some stack frames and limit stack frames by using StackWalker API.Exampleimport java.lang.StackWalker.StackFrame; import java.util.*; import java.util.stream.*; public class StackWalkerTest { public static void main(String args[]) { ...
Read MoreHow can we implement the SubmissionPublisher class in Java 9?
Since Java 9, we can create Reactive Streams by introducing four core interfaces: Publisher, Subscriber, Subscription, Processor, and one concrete class: SubmissionPublisher that implements the Publisher interface. Each interface plays a different role, corresponding to the principles of Reactive Streams. We can use the submit() method of SubmissionPublisher class to publish the provided item to each subscriber.Syntaxpublic class SubmissionPublisher extends Object implements Flow.Publisher, AutoCloseableIn the below example, we can implement the SubmissionPublisher classExampleimport java.util.concurrent.Flow.Subscriber; import java.util.concurrent.Flow.Subscription; import java.util.concurrent.SubmissionPublisher; class MySubscriber implements Subscriber { private Subscription subscription; private String name; public ...
Read MoreHow to add a specific character to any empty space in MySQL table values?
For this, use REPLACE() function and replace empty space with the character. Let us first create a table −mysql> create table DemoTable (Subject text); Query OK, 0 rows affected (0.86 sec)ExampleInsert some records in the table using insert command −mysql> insert into DemoTable values('Introduction to MySQL'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('Java in depth'); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable values('Data Structure and Algorithm'); Query OK, 1 row affected (0.16 sec)Display all records from the table using select statement −mysql> select *from DemoTable;Output+------------------------------+ | Subject | +------------------------------+ | Introduction ...
Read MoreWhat are the core interfaces of Reactive Streams in Java 9?
Java 9 has introduced Reactive Streams under java.util.concurrent.Flow package that supports an interoperable publish-subscribe framework. It processes an asynchronous stream of data across the asynchronous boundary (passing elements into another thread or thread-pool), and the receiving side is not forced to buffer arbitrary amounts of data, then buffer overflow can't occur.Flow API contains four interrelated core interfaces: Publisher, Subscriber, Subscription, and Processor.Syntax@FunctionalInterface public static interface Publisher { public void subscribe(Subscriber
Read MoreHow to terminate/destroy a process using Process API in Java 9?
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 { ...
Read MoreImportance of ofInstant() method in Java 9?
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: " + ...
Read MoreMySQL query to select records from a table on the basis of a particular month number?
You can select specific month with the help of MONTH() function. The syntax is as follows −SELECT yourColumnName FROM yourTableName WHERE MONTH(yourColumnName) = yourValue;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table UserLoginTimeInformation -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserLoginDatetime datetime -> ); Query OK, 0 rows affected (0.55 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into UserLoginTimeInformation(UserLoginDatetime) values(date_add(now(), interval 3 month)); Query OK, 1 row affected (0.14 sec) ...
Read MoreWhat happens when a negative value is inserted to UNSIGNED column in MySQL?
Error occurs when you set a negative value to UNSIGNED column in MySQL. For example, let us first create a table with an UNSIGNED field −mysql> create table UnsignedDemo -> ( -> Id int UNSIGNED -> ); Query OK, 0 rows affected (0.79 sec)The error is as follows whenever you insert negative value to column Id which is declared as UNSIGNED −mysql> INSERT INTO UnsignedDemo VALUES(-100); ERROR 1264 (22003): Out of range value for column 'Id' at row 1ExampleHowever, positive values work well for UNSIGNED. The same is shown in the example below. Insert some records in ...
Read MoreSelect and filter the records on month basis in a MySQL table?
You can use aggregate function SUM() with GROUP BY clause to achieve this.Let us create a table. The query to create a table is as follows −mysql> create table SelectPerMonthDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Price int, -> PurchaseDate datetime -> ); Query OK, 0 rows affected (2.34 sec)ExampleInsert some records in the table using insert command with one of them would be the date of purchase. The query is as follows −mysql> insert into SelectPerMonthDemo(Price, PurchaseDate) values(600, date_add(now(), interval -1 month)); Query OK, 1 row affected (0.42 sec) ...
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