How-to articles, tricks, and solutions about JAVA

In Java 8, the :: (double colon) operator is used to refer to a method or a constructor.

The 'Field required a bean of type that could not be found' error in a Spring application typically indicates that the application is trying to inject a dependency into a field, but it cannot find a bean of the required type in the application context.

If you are getting the error 'Java' is not recognized as an internal or external command, it means that the Java executable is not in your system's PATH. This means that when you try to run the java command, the system does not know where to find it.

The "Content is not allowed in prolog" error typically occurs when you try to parse an XML document that contains characters before the XML prolog (the <?xml ...?> declaration).

In Java, you can create a thread in two ways: by implementing the Runnable interface or by extending the Thread class.

"No X11 DISPLAY variable" is an error message that you might see when trying to run a Java program that uses the X Window System to display a graphical user interface (GUI).

No qualifying bean of type found for dependency is an error message that can occur when you are using the @Autowired annotation in Spring to inject a bean dependency.

In Spring MVC, the @RequestParam annotation is used to bind a request parameter to a method parameter.

In Java, the && and || operators are used in if statements to combine multiple conditions.

To iterate over an enum in Java using a for loop, you can use the values() method of the enum type to get an array of all the enum values, and then use a standard for loop to iterate over the array.

In Java, you can use the AbstractMap.SimpleEntry class from the java.util package to represent a value pair (also known as a tuple).

In Java, a KeyValuePair is a data structure that represents a pair of keys and values, similar to a Map.

To join array elements with a separator in Java, you can use the join method from the String class.

To accept a server's self-signed SSL certificate in a Java client, you can create a custom javax.net.ssl.X509TrustManager and use it to override the default trust manager.

If you are getting an "access restriction" error on a class in your Java code, it means that you are trying to access a class or member (field or method) that has restricted access.

To access a variable from another class in Java, you can use the following steps:

To add an element to an array in Java, you can use one of the following methods:

To add a context path to a Spring Boot application, you can use the server.context-path property in the application's application.properties file.

To add leading zeroes to a number in Java, you can use the format method of the String class, along with a format string that specifies the desired length and padding character.

To add a string to a string array in Java, you can use the Arrays.copyOf() method to create a new array that is one element larger than the original array, and then use a loop to copy the elements of the original array into the new array. Here's an exampl

To add a header to an HTTP request using HttpURLConnection, you can use the setRequestProperty method.

To change the color of a Floating Action Button (FAB) in Android, you can use the setBackgroundTintList() method and pass it a color state list.

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

If the Android SDK installation is unable to find the JDK (Java Development Kit), it could be because the JDK is not installed or is not installed in the default location.

To split a string in Android, you can use the split() method of the String class.