How-to articles, tricks, and solutions about JAVA

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

There are a few ways to tell Jackson to ignore a field during serialization if its value is null. One way is to use the @JsonInclude annotation with the Include.NON_NULL value on the field or class level.

If you are seeing an error message that says "Error: Could not find or load main class", it is likely that there is a problem with the classpath for your project.

To copy a file from one directory to another in Java, you can use the Files.copy method from the java.nio.file package.

In Java, the super keyword is used to refer to the superclass of the current class. It is often used to call the constructor of the superclass, or to access methods or fields of the superclass that have been overridden in the current class.

If you are seeing the error "Cannot determine embedded database driver class for database type NONE" in a Spring Boot application, it means that the application is trying to auto-configure an embedded database, but it is unable to determine which database

To convert an ArrayList containing Integer objects to a primitive int array in Java, you can use the toArray method and a casting operation.

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

In Android, you can use a TextWatcher to listen for changes to the text in a TextView or EditText view.

To verify that a specific method was not called using Mockito, you can use the verifyZeroInteractions method.

To pad an integer with zeros on the left in Java, you can use the String.format() method and specify a minimum field width for the integer. For example:

To perform HTTP basic authentication in Java using the HttpClient library, you can use the UsernamePasswordCredentials class and the BasicCredentialsProvider class.

There are several ways to remove a substring from a given string in Java. Here are a few options:

The java.net.UnknownHostException: Invalid hostname for server: local exception usually indicates that a hostname or an IP address could not be resolved. This can happen for a variety of reasons, such as:

To make the Selenium WebDriver wait for a specified number of seconds in Java, you can use the Thread.sleep method. Here's an example of how you can do this:

In Java, the synchronized keyword is used to provide mutually exclusive access to a shared resource. When a thread tries to execute a synchronized block of code, it will first acquire a lock on the object that the code is synchronized on. If another threa

To handle clicks on items in a RecyclerView, you can set an OnClickListener on the View that represents each item in the RecyclerView.

To find the maximum value in an array of primitives in Java, you can use the Arrays.stream() method to create a stream from the array, and then use the Stream.max() method to find the maximum element in the stream. Here is an example of how to do this for

Without more context, it is difficult to say why subtracting two times would give a strange result. Here are a few potential explanations:

It is common for the Scanner class's next() and nextFoo() methods (where Foo is any primitive type such as Int, Double, etc.) to skip over newline characters in the input. This is because these methods are designed to read only the next token in the input

It is possible that the != operator is not working as expected in your Java code because you are using it to compare object references, rather than the contents of the objects themselves.

If you want to get the generic type of a class at runtime, you can use the Type class in the System namespace.

To determine the class of an object in Java, you can use the getClass() method of the Object class. The getClass() method returns a Class object that represents the object's class.

To convert a char array back to a String in Java, you can use the String class's constructor that takes a char array as an argument.

To set the proxy to be used by the Java Virtual Machine (JVM), you can use the -Dhttp.proxyHost, -Dhttp.proxyPort, and -Dhttp.nonProxyHosts options when starting the JVM.