How-to articles, tricks, and solutions about JAVA

There could be several reasons why you are getting the error "Could not resolve archetype" when trying to create a Maven project in Eclipse.

An interface is a collection of abstract methods that define a set of functions that a class must implement.

To get the first item from a collection in Java, you can use the iterator() method to get an iterator for the collection, and then call the next() method on the iterator to get the first element.

To calculate the difference between two dates in Java, you can use the java.time package (part of Java 8 and later) or the java.util.Calendar class (part of the older java.util package).

To write logs to a text file using java.util.logging.Logger, you will need to do the following:

This error message indicates that you are trying to use a class name in a source code file that is not being processed by the Java compiler.

To convert a date in the format yyyy-MM-dd'T'HH:mm:ss.SSSz to the format yyyy-mm-dd HH:mm:ss, you can use the SimpleDateFormat class in Java.

Here are some examples of how to use the java.util.logging package to log messages in Java:

If you receive the error "Could not find or load main class" in IntelliJ IDEA, it means that the Java Virtual Machine (JVM) cannot find the class with the main method that you are trying to run.

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

In Java 8, the Iterable.forEach() method is a default method that allows you to iterate over the elements of an Iterable (such as a List or Set) and perform a specific action on each element.

To read XML using XPath in Java, you can use the javax.xml.xpath package.

In JUnit, you can use the getClass().getClassLoader().getResource("").getPath() method to get the path of the src/test/resources directory.

If you receive the error "Illegal key size or default parameters" in Java, it means that you are trying to use a cryptographic algorithm with a key size that is not allowed by the jurisdiction policy files.

To set a specific Java version for Maven, you can specify the maven.compiler.source and maven.compiler.target properties in the pom.xml file.

doGet and doPost are methods of the javax.servlet.http.HttpServlet class that are used to handle HTTP GET and POST requests, respectively.

There are several possible reasons why Maven plugins might not be found in IntelliJ:

A NoSuchMethodError is thrown when a program tries to call a method that does not exist in the class or interface.

@SuppressWarnings("unchecked") is an annotation in Java that tells the compiler to suppress specific warnings that are generated during the compilation of the code.

To clone an ArrayList and also clone its contents, you can use the clone method of the ArrayList class, which creates a shallow copy of the list.

To generate a random number in a specific range in Android, you can use the nextInt method of the java.util.Random class.

In Java, a default constructor is a constructor that is automatically generated by the compiler if no other constructors are defined in a class.

In JSON, certain characters must be escaped in strings.

To return a simple string as JSON in a Spring MVC Rest Controller, you can use the @ResponseBody annotation and return the string directly.

One way to write the contents of a Java InputStream to an OutputStream is to use the read and write methods of the InputStream and OutputStream classes.