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How do I populate a drop down with a list using thymeleaf and spring

[solved] caused by: org.hibernate.PersistentObjectException: detached entity passed to persist:

The error looks like org.hibernate.PersistentObjectException: detached entity passed to persist: example.forms.InvoiceItem at org.hibernate.event.def.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:127) at org.hibernate.impl.SessionImpl.firePersist(SessionImpl.java:799) at org.hibernate.impl.SessionImpl.persist(SessionImpl.java:791) …

Jewel Chowdhury November 7, 2021

Java

How to create Spring Boot Application 2021

Hi Devs, Today I am going to show you how to create a simple spring boot project from scratch. Go to spring initializer to generate a spring boot project. Spring…

Jewel Chowdhury September 5, 2021

Interview Questions Java Java Basic

Convert array to ArrayList java

In this article, we are converting an array to ArrayList in Java. We will discuss three different ways to do that. So, I will show how to convert an Array…

Jewel Chowdhury July 7, 2021

Interview Questions Java Java Advanced

Java pass by reference

Is java pass by reference? The answer is NO. Java is always pass-by-value. Today we will learn java pass by reference and java pass by value with examples. Let’s create Person class: package com.example; public…

Jewel Chowdhury July 6, 2021

Java Advanced Java

Java null pointer exception

Today we will learn, What is a NullPointerException, and how do I fix it? So, let’s start: What is NullPointException NullPointException is a RunTimeException. NullPointException is thrown when the value…

Jewel Chowdhury July 6, 2021

Java Java Basic

Operators in Java Explained

Operator are those who performs an action, for example + is an arithmetic operator that perform addition. They are various types of operators are available in java programming language. Types of…

Jewel Chowdhury June 20, 2021

Java Java Basic

Data Types in Java Explained

In Java, data types refer to the type of data that can be stored in variables. Because Java is a tightly typed language, you must define the datatype of variables…

Jewel Chowdhury June 20, 2021

Java Java Basic

Variables in Java Explained

A variable is a term that refers to a value that can be changed in the future. When I put int i=10, for example, the variable name is I and the value…

Jewel Chowdhury June 20, 2021

Java Java Basic

Java Hello World Program

We’ll learn how to write our first Java program throughout this post. This article is only for java beginners. hello world program will be a very simple program that will…

Jewel Chowdhury June 14, 2021

Java Java Basic

Difference between JDK vs JRE vs JVM

Table of contents What is JDKFeatures of JDKWhat is JREFeatures of JREWhat is JVMMain Task of JVMFeatures of JVM What is JDK JDK is the acronym of JAVA Development Kit. JDK…

Jewel Chowdhury June 14, 2021

Java Java Basic

Introduction to Java Programming Language

Java is one of the most used programming languages in the world for developing desktop application and web application. What is JAVA? Java is a platform independent, object oriented programming…

Jewel Chowdhury June 14, 2021

Java Advanced Uncategorized

What is a serialVersionUID and why should I use it?

Serialization Serialization allows to convert an object to a stream, for sending that object over the network OR Save to file OR save into DB for letter usage. serialVersionUID It is…

Jewel Chowdhury June 14, 2021

Guides Java

A JNI error has occurred, please check your installation and try again problem fix 2021

Hi, This is a common problem when you want to run a java program using the command line. The problem is occurring for so many reasons. Most of the cause…

Jewel Chowdhury May 25, 2021

Java Java Advanced

How to handle null pointer exception in Java

NullPointException NullPointException is a RunTimeException. NullPointException is thrown when the value of a reference variable or object is null. How to avoid NullPointException? Before using any object or reference variable,…

Jewel Chowdhury February 7, 2021

Java Java Advanced

How to handle IOException in Java

IOException In Java, IOException is one of the most common Exceptions when the program operates between input and output.IOException is used for input and output-related operations. Sometimes it’s called Input-Output Exception. Whatever the reason…

Jewel Chowdhury February 7, 2021

Java Java Advanced

Exception handling in java with examples

Exception Handling in Java is a powerful mechanism. Exception handling is done to handle the run time error of the program and to maintain normal flow. The exception refers to an abnormal…

Jewel Chowdhury February 7, 2021

Java Java OOP

Java Encapsulation

Binding (or wrapping) code and data together into a single unit are known as encapsulation. For example, a capsule is wrapped with different medicines. Java Encapsulation reduces the code redundancy…

Jewel Chowdhury January 26, 2021

Java Java OOP

Java Abstraction

Hiding internal details and showing functionality is known as abstraction. For example phone call, we don't know the internal processing. The user will have the information on what the object…

Jewel Chowdhury January 26, 2021

Java Java OOP

Java Polymorphism

If one task is performed in different ways, it is known as polymorphism. For example: to convince the customer differently, to draw something, for example, shape, triangle, rectangle, etc. In…

Jewel Chowdhury January 26, 2021

Java Java OOP

Java Inheritance

We will one of the most important concept of JAVA OOP is java inheritance. When one object acquires all the properties and behaviors of a parent object, it is known…

Jewel Chowdhury January 26, 2021