How-to articles, tricks, and solutions about JAVA

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

Jackson is a powerful Java library for processing JSON data. You can use Jackson to deserialize an array of objects by following these steps:

To convert a byte array to a hexadecimal string in Java, you can use the following method:

To extract a substring from a string using a regular expression in Java, you can use the following steps:

To get the first element of a List or Set in Java, you can use the following methods:

There are several ways to convert a string to a string array in Java. Here are a few options:

In Java, you can use the ternary operator (also known as the conditional operator) to create a short form for an if-else statement.

You can use the entrySet() method of the Map interface to get a Set view of the mappings contained in the map, and then create a List from this set using the new

If you are seeing the error "Unfortunately, MyApp has stopped," it means that your Android app has crashed. This can be caused by a number of factors, including:

To remove repeated elements from an ArrayList in Java, you can use the removeAll method and pass it a Collection containing the elements to be removed.

To create an instance of a class using its class name and calling its constructor, you can use the Class.forName method and the newInstance method.

If you see an error message in Eclipse saying "no Java (JRE) / (JDK) ... no virtual machine", it means that Eclipse is unable to find a valid Java installation on your system.

To deploy a WAR (Web ARchive) file in Apache Tomcat 7, you can follow these steps:

In Java, it is not possible to create a generic array directly. However, you can create an array of a specific type and then cast it to a generic type.

An SSL (Secure Sockets Layer) keystore is a storage location for SSL certificates, which are used to establish secure, encrypted connections between a client and a server. The keystore is typically managed by a keystore manager, such as the Java Keytool,

To return a JSON object as a response in Spring Boot, you can use the @ResponseBody annotation and the ObjectMapper class.

To mock and assert a thrown exception in Mockito, you can use the doThrow() method and the verify() method.

To log SQL statements in Spring Boot, you can configure the logging level of the org.hibernate.SQL logger to DEBUG or TRACE.

To convert a boolean value to an integer in Java, you can use the intValue() method of the java.lang.Boolean class, or you can use a conditional operator.

To convert a List<String> to a single string by joining the elements of the list with a separator, you can use the join() method of the java.util.StringJoiner class.

To get the filenames of all files in a folder in Java, you can use the File class and its list method.

There are several ways to initialize a String array in Java. Here are a few examples:

To convert a hashmap to a JSON object in Java, you can use the org.json library. Here's an example:

In Java, the wait() method is used to pause the current thread and allow other threads to execute. It is called on an object and causes the current thread to wait until another thread calls the notify() or notifyAll() method on the same object.

To print a float with 2 decimal places in Java, you can use the printf method and specify a format string with the %.2f format specifier. Here's an example: