This article shows a few examples of filtering a Map by its keys or values using the Java 8 stream APIs. Table of contents: 1. Java Map filter (Classic) 2. Java Map filter (Java 8) 3. Java Map filter (Java 8 Predicate) 4. References 1. Java Map filter (Classic) Before Java 8, we looped the […]
While the unit test is running in the IDE, the Logback is showing a lot of configuration or status like this : 21:16:59,569 |-INFO in ch.qos.logback.classic.LoggerContext[default] – Could NOT find resource [logback.groovy] 21:16:59,569 |-INFO in ch.qos.logback.classic.LoggerContext[default] – Could NOT find resource [logback-test.xml] 21:16:59,569 |-INFO in ch.qos.logback.classic.LoggerContext[default] – Found resource [logback.xml] at … //… omitted for […]
In this tutorial, we will show you few Java 8 examples to demonstrate the use of Streams filter(), collect(), findAny() and orElse() 1. Streams filter() and collect() 1.1 Before Java 8, filter a List like this : BeforeJava8.java package com.mkyong.java8; import java.util.ArrayList; import java.util.Arrays; import java.util.List; public class BeforeJava8 { public static void main(String[] args) […]
In Python, you can simply join two list with a plus + symbol like this: list1 = [1,2,3] list2 = [4,5,6] list3 = list1 + list2 print list3 #[1, 2, 3, 4, 5, 6] Note Try to compare with this Java example – how to join arrays. Python really makes join list extremely easy.
In this article, we will show you a few StringJoiner examples to join String. 1. StringJoiner 1.1 Join String by a delimiter StringJoiner sj = new StringJoiner(","); sj.add("aaa"); sj.add("bbb"); sj.add("ccc"); String result = sj.toString(); //aaa,bbb,ccc 1.2 Join String by a delimiter and starting with a supplied prefix and ending with a supplied suffix. StringJoiner sj […]
In this article, we will show you a few ways to join a Java Array. Apache Commons Lang – ArrayUtils Java API Java 8 Stream 1. Apache Commons Lang – ArrayUtils The simplest way is add the Apache Commons Lang library, and use ArrayUtils. addAll to join arrays. This method supports both primitive and object […]
There are two ways to exclude some unit tests in Gradle. Test filtering (preferred option) Include and exclude Topics. 1. Gradle Test filtering 1.1 Test classes 1.2 Exclude tests from a package 1.3 Exclude a single test using a class name 1.4 Exclude a single method of a test class 1.5 Exclude test methods contains […]
On Debian, you can use apt-cache policy ‘package name’ to check the package version. 1.1 Display Tomcat7 version. $ sudo apt-cache policy tomcat7 tomcat7: Installed: (none) Candidate: 7.0.52-1ubuntu0.3 Version table: 7.0.52-1ubuntu0.3 0 500 http://archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages 500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages 7.0.52-1 0 500 http://archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages 1.2 Display OpenJDK-7 version. $ sudo […]
This article shows you the difference between Mutable and Immutable objects in Java 1. Mutable object – You can change the states and fields after the object is created. For examples: StringBuilder, java.util.Date and etc. 2. Immutable object – You cannot change anything after the object is created. For examples: String, boxed primitive objects like […]
By default, the Gradle build process will be stopped and failed if any unit test is failed. $ gradle build :clean :compileJava :processResources :classes :compileTestJava :processTestResources UP-TO-DATE :testClasses :test com.mkyong.example.TestExample > test_example FAILED java.lang.Exception at TestExample.java:9 //… 3 tests completed, 1 failed :test FAILED //… BUILD FAILED // <————– see status In this article, we […]
By default, gradle test displays only the test summary. Terminal % gradle test BUILD SUCCESSFUL in 4s 6 actionable tasks: 3 executed, 3 up-to-date P.S Gradle test generates the detailed tests’ result at the build/reports/tests/test/index.html page. P.S Tested with Gradle 6.7.1 1. Display test result in the console. 1.1 We add the testLogging events to […]
In this article, we will show you a few ways to print a Java Array. Table of contents. 1. JDK 1.5 Arrays.toString 2. Java 8 Stream APIs 3. Java 8 Stream APIs – Collectors.joining 4. Jackson APIs 5. References 1. JDK 1.5 Arrays.toString We can use Arrays.toString to print a simple array and Arrays.deepToString for […]
Gradle example to exclude commons-logging from Spring frameworks. build.gradle compile(‘org.springframework:spring-webmvc:4.2.4.RELEASE’){ exclude group: ‘commons-logging’, module: ‘commons-logging’ } If you have multiple Spring dependencies, you have to exclude for each build.gradle compile(‘org.springframework:spring-webmvc:4.2.4.RELEASE’){ exclude group: ‘commons-logging’, module: ‘commons-logging’ } compile(‘org.springframework:spring-test:4.2.4.RELEASE’){ exclude group: ‘commons-logging’, module: ‘commons-logging’ } A better solution is excluding commons-logging at the project level. build.gradle configurations.all […]
Create a Gradle project in Jenkins CI, source management with Git, and build with Gradle Wrapper 1. Problem Jenkins console output, the build is failed – “Could not find org.gradle.wrapper.GradleWrapperMain” [Gradle] – Launching build. [workspace] $ /var/lib/jenkins/jobs/GradleTest/workspace/gradlew clean test Error: Could not find or load main class org.gradle.wrapper.GradleWrapperMain Build step ‘Invoke Gradle script’ changed build […]
In this tutorial, we will show you how to create Gradle wrapper for your project and how to use it. What is Gradle wrapper? The Gradle wrapper allows you to run a Gradle task without requiring that Gradle is installed on your system. 1. Create a Gradle Wrapper 1.1 Declares a wrapper task. build.gradle task […]
A Gradle build + JaCoCo coverage report. build.gradle apply plugin: ‘java’ apply plugin: ‘eclipse-wtp’ apply plugin: ‘jacoco’ //code coverage repositories { mavenLocal() mavenCentral() } jacoco { toolVersion = "0.7.5+" } jacocoTestReport { reports { html.enabled = true xml.enabled = true csv.enabled = false } } P.S Tested with Gradle 2.10 1. Problem 1.1 Run the […]
In this tutorial, we will show you how to ‘hot deploy’ or ‘hot swap’ a web application in IDEA. Note Tested with Intellij IDEA 14 and 15 1. Select exploded WAR Go Run –>> Edit Configurations –>> “Deployment” tab, clicks + icon –>> select an “exploded artifact” 2. Update classes and resources Select “Server” tab, […]
In Maven, we can use the official JBoss WildFly Maven Plugin to deploy a web application (war file) to the WildFly application server. Technologies tested : Maven 3.3.9 WildFly 9.0.2.final WildFly Maven Plugin 1.1.0.Alpha5 P.S This Spring MVC web application will be used for this deployment test. 1. Deploy WAR To WildFly 1.1 Start WildFly […]
Maven package a web application and hits the following error message : $ mvn package //… [ERROR] Failed to execute goal org.apache.maven.plugins:maven-war-plugin:2.2:war (default-war) on project spring4-mvc-maven-ajax-example: Error assembling WAR: webxml attribute is required (or pre-existing WEB-INF/web.xml if executing in update mode) -> [Help 1] Solution 1. For servlet container < 3, make sure WEB-INF/web.xml file […]
In this tutorial, we will show you a Spring MVC + Mustache JS template web application example. Technologies used : Spring 4.2.4.RELEASE mustache.js JDK 1.8.0_66 Jackson 2.7 Eclipse 4.3 Tomcat 8 Maven 3 Bootstrap 3 Note This solution is still working, but recommend this simple Spring Boot + JMustache solution. In Spring, we can use […]
Start a Java webapp with Maven Jetty plugin. $ mvn jetty:run 1. Problem But it hits the following error messages : [WARNING] FAILED org.eclipse.jetty.maven.plugin.JettyServer@1f53481b: java.net.BindException: Address already in use at sun.nio.ch.Net.bind0(Native Method) at sun.nio.ch.Net.bind(Net.java:433) at sun.nio.ch.Net.bind(Net.java:425) at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:223) at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74) at org.eclipse.jetty.server.ServerConnector.open(ServerConnector.java:321) at org.eclipse.jetty.server.AbstractNetworkConnector.doStart(AbstractNetworkConnector.java:80) //… 2. Solution By default, the maven-jetty-plugin start Jetty on port […]
Always, Java developers need to know which application is using the high demand 8080 port. In this tutorial, we will show you two ways to find out which application is using port 8080 on Linux. 1. lsof + ps command 1.1 Bring up the terminal, type lsof -i :8080 $ lsof -i :8080 COMMAND PID […]
Review a jQuery Ajax form submit. $(document).ready(function () { $("#hostingForm").submit(function (e) { e.preventDefault(e); var data = {} data["id"] = $("#id").val(); data["domain"] = $("#domain").val(); data["name"] = $("#name").val(); //… $.ajax({ type: "POST", contentType: "application/json", url: "{{home}}/hosting/update", data: JSON.stringify(data), dataType: ‘json’, timeout: 600000, success: function (data) { console.log("SUCCESS: ", data); }, error: function (e) { console.log("ERROR: ", e); […]
To view the request or response HTTP headers in Google Chrome, take the following steps : In Chrome, visit a URL, right click, select Inspect to open the developer tools. Select Network tab. Reload the page, select any HTTP request on the left panel, and the HTTP headers will be displayed on the right panel.
By default, Meteor app start on port 3000 $ meteor [[[[[ ~/path-to/meteor/hello ]]]]] => Started proxy. => Started MongoDB. => Started your app. => App running at: http://localhost:3000/ 1. Meteor Port 9999 To start Meteor app on a different port, start Meteor with –port parameter. $ meteor –port 9999 [[[[[ ~/path-to/meteor/app ]]]]] => Started proxy. […]
Review the below @PathVariable example. @RequestMapping("/site") public class SiteController { @RequestMapping(value = "/{q}", method = RequestMethod.GET) public ModelAndView display(@PathVariable("q") String q) { return getModelAndView(q, "site"); } } See the following cases : For input /site/google, q = google For input /site/google.com, q = google where is the .com? For input /site/google.com.my, q = google.com For […]
In this tutorial, we will show you how to create a website with Meteor framework. Tools used : Meteor 1.2.1 Tested with Linux (Debian, Ubuntu or Mint) Tested with Mac OSX 1. Install Meteor Issue curl https://install.meteor.com | sh, everything will be installed and configured. $ curl https://install.meteor.com | sh % Total % Received % […]
Few examples to show you how to split a String into a List in Python. 1. Split by whitespace By default, split() takes whitespace as the delimiter. alphabet = "a b c d e f g" data = alphabet.split() #split string into a list for temp in data: print temp Output a b c d […]
In this tutorial, we will show you how to use for-in-loop to loop a List in Python. #example 1 frameworks = [‘flask’, ‘pyramid’, ‘django’] #list for temp in frameworks: print temp print "Python framework : %s" %temp #example 2 numbers = [2,4,6,8,10] #list for num in numbers: print num print "Number : %d" %num Output […]
Reviewing a jQuery Ajax form POST and Spring MVC example, find out the following patterns : <script> jQuery(document).ready( function($) { $("#btn-save").click(function(event) { var id = $(‘#id’).val(); var domain = $(‘#domain’).val(); var name = $(‘#name’).val(); var desc = $(‘#desc’).val(); var tags = $(‘#tags’).val(); var afflink = $(‘#afflink’).val(); var cdn = $("#cdn").prop("checked") ? true : false; var […]
Spring doesn’t allow to inject value into static variables, for example: import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component public class GlobalValue { @Value("${mongodb.db}") public static String DATABASE; } If you print out the GlobalValue.DATABASE, a null will be displayed. GlobalValue.DATABASE = null Solution To fix it, create a “none static setter” to assign the injected value for […]
In this tutorial, we will show you how to install Oracle JDK 8 On Debian, manually. Environment : Debian 7 OpenJDK 1.7 is installed. (Switch to Oracle JDK 8 later) At the time of writing, OpenJDK 1.8 is not included in the default apt-get repository yet. I just don’t like the default apt repository schedule, […]
In this tutorial, we will show you how to install Apache Tomcat 8 On Debian, manually. Environment : Debian 7 JDK 1.8 Apache Tomcat 8 P.S Assume the JDK 1.8 is installed in /opt/jdk folder. Refer to this guide to install Oracle JDK 8 on Debian. Note On Debian 7, the Tomcat 8 is not […]
In Java 8, you can use Files.lines to read file as Stream. c://lines.txt – A simple text file for testing line1 line2 line3 line4 line5 1. Java 8 Read File + Stream TestReadFile.java package com.mkyong.java8; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; import java.util.stream.Stream; public class TestReadFile { public static void main(String args[]) { String fileName […]
In Java, the System.getenv() returns an unmodifiable string Map view of the current system environment. Map<String, String> env = System.getenv(); // get PATH environment variable String path = System.getenv("PATH"); Table of contents. 1. Get a specified environment variable 2. UnsupportedOperationException 3. Display all environment variables 4. Sort the environment variables 5. Download Source Code 6. […]
In this tutorial, we will show you how to use Jackson 2.x to convert Java objects to / from a JSON. 1. Basic 1.1 Convert a Staff object to from JSON. writeValue(…) – Java Objects to JSON ObjectMapper mapper = new ObjectMapper(); // Java object to JSON file mapper.writeValue(new File("c:\\test\\staff.json"), new Staff()); // Java object […]
In this tutorial, we will show you how to create a Spring MVC web project and submit a form via Ajax. Technologies used : Spring 4.2.2.RELEASE Jackson 2.6.3 Logback 1.1.3 jQuery 1.10.2 Maven 3 JDK 1.8 Tomcat 8 or Jetty 9 Eclipse 4.5 Boostrap 3 P.S If the Jackson library is found in the project […]
Performs a large sort operation (Aggregation) in a collection, and hits the following error message : MongoDB Console > db.bigdata.aggregate( {$group : {_id : "$range", total : { $sum : 1 }}}, {$sort : {total : -1}} ); #… aggregate failed at Error (<anonymous>) at doassert (src/mongo/shell/assert.js:11:14) #… Error: command failed: { "errmsg" : "exception: […]
In Java, we can use String#split() to split a string. String phone = "012-3456789"; // String#split(string regex) accepts regex as the argument String[] output = phone.split("-"); String part1 = output[0]; // 012 String part2 = output[1]; // 3456789 Table of contents 1. Split a string (default) 2. Split a string and retain the delimiter 3. […]
In Java, we can use TimeUnit.SECONDS.sleep() or Thread.sleep() to delay few seconds. 1. TimeUnit JavaDelayExample.java package com.mkyong; import java.util.Date; import java.util.concurrent.TimeUnit; public class JavaDelayExample { public static void main(String[] args) { try { System.out.println("Start…" + new Date()); // delay 5 seconds TimeUnit.SECONDS.sleep(5); System.out.println("End…" + new Date()); // delay 0.5 second //TimeUnit.MICROSECONDS.sleep(500); // delay 1 minute […]
