w3docs logo
  1. Snippets
    2. ›
  2. java

How-to articles, tricks, and solutions about JAVA

:: (double colon) operator in Java 8

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

java java-8

'Field required a bean of type that could not be found.' error spring restful API using mongodb

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.

java spring rest mongodb

'Java' is not recognized as an internal or external command

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.

java

"Content is not allowed in prolog" when parsing perfectly valid XML on GAE

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).

xml java parsing google-app-engine stax

"implements Runnable" vs "extends Thread" in Java

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

java implements multithreading java-threads runnable

"No X11 DISPLAY variable" - what does it mean?

"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).

java linux variables x11 headless

@Autowired - No qualifying bean of type found for dependency

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.

java spring spring-mvc annotations autowired

@RequestParam vs @PathVariable

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

java spring spring-mvc

&& (AND) and || (OR) in IF statements

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

java if-statement

A for-loop to iterate over an enum in Java

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.

java loops enums for-loop