Edit this file /private/etc/hosts. Terminal $ sudo nano /private/etc/hosts ## # Host Database # # localhost is used to configure the loopback interface # when the system is booting. Do not change this entry. ## 127.0.0.1 localhost 255.255.255.255 broadcasthost ::1 localhost fe80::1%lo0 localhost 127.0.0.1 mkyong-mac 198.x.x.x linode-bot1 1.2.3.4 www.google.com References What is the difference between […]
Review the server environment, we need to allow Server B to access the Server A MongoDB database. Server A – MongoDB server Private IP – 192.168.162.129 / 17 Server B – Application Server Private IP – 192.168.204.205 / 17 Update the bind_ip, but unable to start mongod process anymore. /etc/mongod.conf #$ vim /etc/mongod.conf # Listen […]
Upgraded MongoDB and unable to start the mongod process, review the /var/log/mongodb/mongod.log file, and found the following error messages : Terminal 2017-08-24T03:57:21.289-0400 I CONTROL [initandlisten] MongoDB starting : pid=31927 port=27017 dbpath=/var/lib/mongodb3 64-bit host=hcompass 2017-08-24T03:57:21.289-0400 I CONTROL [initandlisten] db version v3.2.16 2017-08-24T03:57:21.289-0400 I CONTROL [initandlisten] git version: 056bf45128114e44c5358c7a8776fb582363e094 2017-08-24T03:57:21.289-0400 I CONTROL [initandlisten] OpenSSL version: OpenSSL 1.0.1t […]
The ALTER FUNCTION statement explicitly recompile a standalone function. Sometimes, ALTER TABLE on the table being used in function will cause the function becomes INVALID, we need to recompile (alter function) it to make it VALID again. 1. ALTER function example First, we will create table test_alter, function get_max_amount. In this function, we are using […]
This article show you how to use ATAN() and ATAN2() function in Oracle PL/SQL. 1. ATAN function examples The ATAN function returns the arc tangent of n, the n can be in an unbounded range. The function will returns a value in the range of -pi/2 to pi/2, expressed in radians. SELECT ATAN(1.5) FROM DUAL; […]
The CEIL function round the specified number up, and return the smallest number that is greater than or equal to the specified number. CEIL function examples SELECT CEIL(1.2) FROM DUAL; — output : 2 SELECT CEIL(1.5) FROM DUAL; — output : 2 SELECT CEIL(1.7) FROM DUAL; — output : 2 SELECT CEIL(1.99) FROM DUAL; — […]
The FLOOR() function round the specified number down, and return the largest number that is less than or equal to the specified number. FLOOR function examples SELECT FLOOR(1.2) FROM DUAL; — output : 1 SELECT FLOOR(1.5) FROM DUAL; — output : 1 SELECT FLOOR(1.7) FROM DUAL; — output : 1 SELECT FLOOR(1.99) FROM DUAL; — […]
The ACOS() function returns the arc cosine of input n, the input n must be in the range of -1 to 1. The function will return a value in the range of 0 to pi, expressed in radians. ACOS function examples SELECT ACOS(.2) FROM DUAL; — output 1.36943840600456582777619613942212803186 SELECT ACOS(-.4) FROM DUAL; — output 1.98231317286238463861605958925708704694 […]
A Java example to print half and full pyramid, for fun. CreatePyramid.java package com.mkyong; import java.util.Collections; public class CreatePyramid { public static void main(String[] args) { int rows = 5; System.out.println("\n1. Half Pyramid\n"); for (int i = 0; i < rows; i++) { for (int j = 0; j <= i; j++) { System.out.print("*"); } […]
The ASIN() function returns arc sine of input n, the input n must be in the range of -1 to 1. The function will return a value in the range of -pi/2 to pi/2, expressed in radians. ASIN function examples SELECT ASIN(.25) FROM DUAL; — output 0.25268025514207865348565743699370756609 SELECT ASIN(-.5) FROM DUAL; — output -0.52359877559829887307710723054658381405 SELECT […]
This ABS() function returns absolute value of a number, for example, the absolute value of 5 is 5, and the absolute value of -5 is also 5. In Mathematics, absolute value can be think of as a distance from zero. ABS function examples SELECT ABS(-15) FROM DUAL; — 15 SELECT ABS(-51.321) FROM DUAL; –51.321 SELECT […]
This article shows you how to use INSTEAD OF TRIGGER to update A noneditioning view A nested table column of a noneditioning view This INSTEAD OF triggers provide a way to modify views that cannot be modified directly through DML statements like INSERT, UPDATE and DELETE An INSTEAD OF trigger is Always a row-level trigger. […]
This article shows you how to use BEFORE DELETE TRIGGER, it will fire before the delete operation is executed. In real life scenarios, it is mostly used for purposes like: Restrict invalid DELETE operation. Delete data from another table. 1. Restrict invalid DELETE operation In this example, We have two tables item_details and order_details. The […]
This article shows you how to use Apache PDFBox to read a PDF file in Java. 1. Get PDFBox pom.xml <dependency> <groupId>org.apache.pdfbox</groupId> <artifactId>pdfbox</artifactId> <version>2.0.6</version> </dependency> 2. Print PDF file Example to extract all text from a PDF file. ReadPdf.java package com.mkyong; import org.apache.pdfbox.pdmodel.PDDocument; import org.apache.pdfbox.text.PDFTextStripper; import org.apache.pdfbox.text.PDFTextStripperByArea; import java.io.File; import java.io.IOException; public class ReadPdf { […]
A simple Python example to print half and full pyramid, just for fun. def half_pyramid(rows): print(‘Half pyramid…\n’) for i in range(rows): print(‘*’ * (i+1)) def full_pyramid(rows): print(‘\nFull pyramid…\n’) for i in range(rows): print(‘ ‘*(rows-i-1) + ‘*’*(2*i+1)) def inverted_pyramid(rows): print(‘\nInverted pyramid…\n’) for i in reversed(range(rows)): print(‘ ‘*(rows-i-1) + ‘*’*(2*i+1)) half_pyramid(5) full_pyramid(5) inverted_pyramid(5) Output Half pyramid… * […]
This article shows you how to use DROP FUNCTION to delete a function from Oracle database. 1. DROP function example 1.1 Create a function get_current_month. Then we will delete the function using DROP FUNCTION statement. –Creating function CREATE OR REPLACE FUNCTION get_current_month RETURN VARCHAR2 IS curr_month VARCHAR2(10); BEGIN SELECT to_char(sysdate, ‘MONTH’) INTO curr_month FROM dual; […]
Check the USER_TRIGGERS table, you can get the Trigger status easily : — display all triggers for users SELECT TRIGGER_NAME,STATUS FROM USER_TRIGGERS; — display status for a specified trigger SELECT TRIGGER_NAME,STATUS FROM USER_TRIGGERS WHERE TRIGGER_NAME = ‘TRIGGER_NAME’; SELECT TRIGGER_NAME,STATUS FROM USER_TRIGGERS WHERE TRIGGER_NAME IN(‘TRIGGER_NAME_A’, ‘TRIGGER_NAME_B’); Sample data. TRIGGER_NAME STATUS TRIGGER_NAME_A ENABLED TRIGGER_NAME_B DISABLED TRG_BEFORE_EMP_UPDATE ENABLED […]
This article shows you how to use BEFORE UPDATE TRIGGER, it’s fire before the update operation is executed. In real life scenarios, it is mostly used for purposes like: Data validation Update values automatically Data logging, or auditing 1. Data Validation Suppose some companies have job openings and already having application data and the criteria […]
This article shows you how to use DROP TRIGGER to delete a trigger. — delete a trigger DROP TRIGGER trigger_name; Note In DROP TRIGGER statement, recommend to specify a schema name before trigger name. If you don’t specify a schema name, then database will assume that the trigger is in your own schema. 1. Table […]
This article shows you how to use ALTER TRIGGER and ALTER TABLE to enable and disable triggers. — enable / disable a trigger ALTER TRIGGER trigger_name ENABLE; ALTER TRIGGER trigger_name DISABLE; — enable / disable all triggers for a specific table ALTER TABLE table_name ENABLE ALL TRIGGERS; ALTER TABLE table_name DISABLE ALL TRIGGERS; 1. Table […]
This article shows you how to use BEFORE INSERT TRIGGER, it’s fire BEFORE an INSERT operation is executed. In real life scenarios, it is mostly used for purposes like Data validation Update values automatically (e.g CREATED_BY, CREATION_DATE etc) 1. Table Create a employee_details, we will try to insert different values into this table and observe […]
Jacoco is used to measure the code coverage of application. In this tutorial we will understand how to configure Jacoco in maven and how to use Jacoco to see code coverage report. Technologies Used: Eclipse Mars Maven 3.3.9 Java 8 1. Eclipse Create Maven Java Project 1.1 In Eclipse create a Maven project File->New->Project->Maven Project, […]
Mkyong.com is one of the media partners for the coming JAX London 2017, in return, they are offering a 10% discount code for all the Mkyong.com readers. 10% discount code for JAX London 2017 mp_mky_10 Visit the JAX London official page So, What is JAX London? JAX London is a four-day conference for cutting-edge software […]
Example to use cURL -X PUT to send a PUT (update) request to update the user’s name and email. Terminal $ curl -X PUT -d ‘name=mkyong&[email protected]’ http://localhost:8080/user/100 If the REST API only accepts json formatted data, try this Terminal $ curl -X PUT -H "Content-Type: application/json" -d ‘{"name":"mkyong","email":"[email protected]"}’ http://localhost:8080/user/100 References cURL official website cURL – […]
To send a DELETE request, uses cURL -X DELETE Terminal $ curl -X DELETE http://localhost:8080/user/100 The above example will delete a user where user id is 100. References cURL official website cURL – POST request examples
In pom.xml, defined this maven.compiler.source properties to tell Maven to use Java 8 to compile the project. 1. Maven Properties Java 8 pom.xml <properties> <maven.compiler.target>1.8</maven.compiler.target> <maven.compiler.source>1.8</maven.compiler.source> </properties> Java 7 pom.xml <properties> <maven.compiler.target>1.7</maven.compiler.target> <maven.compiler.source>1.7</maven.compiler.source> </properties> 2. Compiler Plugin Alternative, configure the plugin directly. pom.xml <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.6.1</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> […]
A Spring Boot Thymeleaf example, uses Spring Security to protect path /admin and /user Technologies used : Spring Boot 1.5.3.RELEASE Spring 4.3.8.RELEASE Spring Security 4.2.2 Thymeleaf 2.1.5.RELEASE Thymeleaf extras Spring Security4 2.1.3 Tomcat Embed 8.5.14 Maven 3 Java 8 1. Project Directory 2. Project Dependencies Declares spring-boot-starter-security, it will get anything you need to develop […]
This article shows you how to use AFTER INSERT TRIGGER, it will fire after the insert operation is executed. 1. After INSERT Trigger In this example, if a new user is created in user_details, but fields like passport_no or driving_license_no is missing, a new record will be inserted into user_reminders via ‘after insert’ trigger on […]
The following SQL shows you how to get the source code for a specified trigger : select text from user_source where name =’&trigger_name’ and type =’TRIGGER’; References Oracle database – USER_SOURCE table
In Spring Boot + Mustache template environment, if we didn’t assign a value to a {{variable}} on the Mustache’s page, the jmustache will throws the following error messages : com.samskivert.mustache.MustacheException$Context: No method or field with name ‘variable’ on line xx at com.samskivert.mustache.Template.checkForMissing(Template.java:316) ~[jmustache-1.13.jar:na] at com.samskivert.mustache.Template.getValue(Template.java:224) ~[jmustache-1.13.jar:na] at com.samskivert.mustache.Template.getValueOrDefault(Template.java:269) ~[jmustache-1.13.jar:na] P.S Tested with Spring Boot 1.5.2.RELEASE […]
A Spring Boot web application example, using embedded Tomcat + Mustache template engine, and package as an executable JAR file. Technologies used : Spring Boot 1.5.2.RELEASE Spring 4.3.7.RELEASE jmustache 1.13 Thymeleaf 2.1.5.RELEASE Tomcat Embed 8.5.11 Maven 3 Java 8 Note Spring Boot uses jmustache to integrate Mustache as template engine. 1. Project Directory 2. Project […]
Apache Solr is an Open-source REST-API based Enterprise Real-time Search and Analytics Engine Server from Apache Software Foundation. It’s core Search Functionality is built using Apache Lucene Framework and added with some extra and useful features. It is written in Java Language. SOLR stands for Searching On Lucene w/Replication. It’s main functionalities are indexing and […]
Java examples to show you how to convert a comma-separated String into a List and vice versa. 1. Comma-separated String to List TestApp1.java package com.mkyong.utils; import java.util.Arrays; import java.util.List; public class TestApp1 { public static void main(String[] args) { String alpha = "A, B, C, D"; //Remove whitespace and split by comma List<String> result = […]
In Java, you can use Collections.shuffle to shuffle or randomize a ArrayList TestApp.java package com.mkyong.utils; import java.util.Arrays; import java.util.Collections; import java.util.List; public class TestApp { public static void main(String[] args) { List<String> list = Arrays.asList("A", "B", "C", "D", "1", "2", "3"); //before shuffle System.out.println(list); // again, same insert order System.out.println(list); // shuffle or randomize Collections.shuffle(list); […]
In Spring framework, you can @Autowired a HttpServletRequest in any Spring managed bean directly, and later get the client’s IP address from the request headers WebUtils.java package com.mkyong.web; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component; import javax.servlet.http.HttpServletRequest; @Component public class WebUtils { private HttpServletRequest request; @Autowired public void setRequest(HttpServletRequest request) { this.request = request; } private static String […]
In Java 8, stream().map() lets you convert an object to something else. Review the following examples : 1. A List of Strings to Uppercase 1.1 Simple Java example to convert a list of Strings to upper case. TestJava8.java package com.mkyong.java8; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; public class TestJava8 { public static void […]
This article shows you how to use AFTER UPDATE TRIGGER, it will fire after the update operation is executed. 1. Logging example In this example, after each update on ‘SALARY’ column of employee_salary, it will fire a ‘after update’ trigger and insert the new updated data into a employee_salary_log table, for audit purpose. 1.1 Create […]
A series of Java 8 tips and examples, hope you like it. FAQs Some common asked questions. Java 8 forEach examples Java 8 Convert List to Map Java 8 Lambda : Comparator example Java 8 method references, double colon (::) operator Java 8 Streams filter examples Java 8 Streams map() examples 1. Functional Interface Java […]
This article shows you how to download a file from an URL by using the following methods : Apache Commons IO Java NIO 1. Apache Commons IO 1.1 This is still my prefer way to download a file from the Internet, simple and clean. Read the signature : org.apache.commons.io.FileUtils //int = number of milliseconds public […]
Run a Jackson related project and hits the following JsonMerge not found error. Console java.lang.NoClassDefFoundError: com/fasterxml/jackson/annotation/JsonMerge at com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector.<clinit>(JacksonAnnotationIntrospector.java:50) ~[jackson-databind-2.9.0.pr1.jar:2.9.0.pr1] at com.fasterxml.jackson.databind.ObjectMapper.<clinit>(ObjectMapper.java:292) ~[jackson-databind-2.9.0.pr1.jar:2.9.0.pr1] at com.hostingcompass.core.utils.PrintUtils.<clinit>(PrintUtils.java:9) ~[main/:na] at com.hostingcompass.app.run.TurtleApp.run(TurtleApp.java:25) ~[main/:na] at com.hostingcompass.app.Main.run(Main.java:42) [main/:na] at org.springframework.boot.SpringApplication.callRunner(SpringApplication.java:776) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at org.springframework.boot.SpringApplication.callRunners(SpringApplication.java:760) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at org.springframework.boot.SpringApplication.afterRefresh(SpringApplication.java:747) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1162) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1151) [spring-boot-1.5.2.RELEASE.jar:1.5.2.RELEASE] at com.hostingcompass.app.Main.main(Main.java:34) [main/:na] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) […]
