How to Pretty Print JSON output in cURL
In cURL requests, the default JSON output is in compact format. Terminal curl https://api.cloudflare.com/client/v4/ {"success":false,"errors":[{"code":7000,"message":"No route for that URI"}],"messages":[],"result":null} In cURL, we can use or pipe the json_pp to pretty print the JSON output. Terminal curl https://api.cloudflare.com/client/v4/ |...
How to exit JShell in Java?
To exit JShell, type /exit. I stuck in JShell for minutes, commands like exit, ctrl + c, end, q!, q, quit all failed, the correct syntax to quit or exit the JShell is /exit. Terminal C:\Users\mkyong>jshell | Welcome to JShell -- Version 11.0.1 | For an introduction type: /help intro jshell> exit | Error: | cannot find symbol | symbol: variable exit | exit | ^--^ jshell> q | Error: | cannot find...
How to list containers in Docker?
In Docker, we can use docker ps to show all running containers, docker ps -a to show all running and stopped containers. Here are some of the commonly used examples: Terminal # common $ docker ps // show only running containers $ docker ps -a // show all containers (running and stopped or exited) # recent containers $ docker ps -l // To show the...
Java 8 Supplier Examples
In Java 8, Supplier is a functional interface; it takes no arguments and returns a result. Supplier.java @FunctionalInterface public interface Supplier<T> { T get(); } 1. Supplier 1.1 This example uses Supplier to return a current date-time. Java8Supplier1.java package com.mkyong; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; import java.util.function.Supplier; public class...
Java SSLSocket TLS 1.3 example
This Java 11 JEP 332 adds support for TLS 1.3 protocol. SSLSocket + TLS 1.3 An SSLSocket client with TLS1.3 protocol and TLS_AES_128_GCM_SHA256 stream cipher, to send a request to https://google.com and print the response. JavaTLS13.java package com.mkyong.java11.jep332; import javax.net.ssl.SSLSocket; import javax.net.ssl.SSLSocketFactory; import java.io.*; // Java 11 public class JavaTLS13 { private static final...
Java 11 shebang example in Docker
In Java 11, JEP 330 adds support to run single-file source code directly. Terminal # Before Java 11 $ javac Hello.java $ java Hello # Now Java 11 $ java Hello.java This indirectly supports the Java single-file program to run as a script using Unix Shebang. For example, run below .sh file will print Hello World!. run.sh #!/opt/java/openjdk/bin/java --source 11 public class SheBang { public static void main(String[]...
Java - What is serialVersionUID
In Java, serialVersionUID is something like version control, assure both serialized and deserialized objects are using the compatible class. For example, if an object saved into a file (Serialization) with serialVersionUID=1L, when we convert the file back to an object (Derialization), we must use the same serialVersionUID=1L, otherwise an InvalidClassException is thrown. Terminal Exception in thread "main"...
Java - What is transient fields?
In Java, transient fields are excluded in the serialization process. In short, when we save an object into a file (serialization), all transient fields are ignored. 1. POJO + transient Review the following Person class; the salary field is transient. public class Person implements Serializable { private static final long serialVersionUID = 1L; private String name; private int age; // ignore this field ...