How-to articles, tricks, and solutions about JAVA

In a JPA entity relationship, the CascadeType.ALL annotation specifies that all operations (persist, merge, remove, refresh, and detach) that are performed on the parent entity should be cascaded to the child entity.

In Java, a class can be marked as final, which means that it cannot be subclassed. This can be useful in a number of situations:

The printStackTrace() method is a method of the Throwable class (the parent class of Exception) that prints the stack trace of the exception to the standard error stream.

The date format "2011-08-12T20:17:46.384Z" is an ISO 8601 extended format, which is often used for exchanging date and time information in a machine-readable format.

When overriding the equals() and hashCode() methods in Java, you should consider the following issues:

A java.net.SocketException: Connection reset can be caused by a variety of issues, such as:

In Spring, the @Component annotation is used to mark a Java class as a candidate for component scanning. The @Repository annotation is a specialization of @Component for use in the persistence layer.

Java Persistence API (JPA) is a specification for object-relational mapping (ORM) in Java.

In Java 8, the map() and flatMap() methods are part of the Stream API, and are used to transform the elements of a stream.

There are several ways to print an array in Java. Here are a few options: Using a loop

The syntax for mod in Java is the percent sign %. For example, a % b returns the remainder of a divided by b.

The @Override annotation in Java is used to indicate that a method is intended to override a method declared in a superclass or interface.

The @JsonProperty annotation is used to specify the property name in a JSON object when serializing or deserializing a Java object using the Jackson library.

In Java, the finalize method is called by the garbage collector when it determines that an object is no longer reachable.

In Java, the File.separator field is a string that represents the separator character used in file paths on the current operating system.

In a Java RESTful web service, the @QueryParam annotation is used to bind a query parameter to a method parameter, while the @PathParam annotation is used to bind a path parameter to a method parameter.

In Java, both ArrayList and LinkedList are implementations of the List interface that allow you to store a collection of objects in a specific order. However, they are implemented differently and have different performance characteristics.

In Java, static methods are methods that belong to a class rather than an instance of the class. They can be called without creating an instance of the class, using the name of the class and the dot operator (.).

In JavaScript, the length property of an array is defined on the Array.prototype.

On Mac OS X, the default location for the JDK (Java Development Kit) is /Library/Java/JavaVirtualMachines/jdk<version>.jdk/Contents/Home/, where <version> is the version number of the JDK you have installed.

On macOS, the JAVA_HOME environment variable is typically set in the /etc/launchd.conf file.

In Java, you can use the following regular expression to match any amount of whitespace:

A NoClassDefFoundError in Java indicates that the Java Virtual Machine (JVM) or a ClassLoader was not able to find the definition of a class that was referenced in your code. This can occur for a variety of reasons, including:

In Java, interface variables are static and final by default because that is how they are defined in the Java Language Specification (JLS).

In the Java programming language, you can use a switch statement to choose between a fixed number of alternatives.