Java

@Validated @Valid mark a member attribute for validation ✖️ ✅ group-level validation ✅ ️ ✖️ mark request parameter for validation ✅ ✅ Example 1 Example 2 This note borrows code from Differences in @Valid and @Validated Annotations in Spring

Sometimes you would see such warning msg like the above in your Intellij, this means you need to handle the exception: add exception to method signature, or surround with try/catch. But why you can throw some exceptions without these handling, and why you can't throw some? The

Wildcards How to write a generic interface with List or Collection of implemented class of the interface? I encounter to this problem when I write a tree node interface, here is the details of the problem: I need to create an interface for the following two classes, how to write

Method Overriding and Variable Hiding In Java, methods are overridden, but variables can only be hidden. In the case of method overriding, overriding methods completely replace the inherited methods but in variable hiding, the child class hides the inherited variables instead of replacing them which basically means that the object

Maven Dependency <dependency> <groupId>org.apache.commons</groupId> <artifactId>commons-collections4</artifactId> <version>4.1</version> </dependency> Difference between subtract and removeAll You can use CollectionUtils.removeAll(collection, remove) or CollectionUtils.subtract(collection, remove) to

There are circumstances in that we need to override a bean's methods which is from an external package but keep the same bean name. We can achieve this by replacing bean definition during application startup using BeanFactoryPostProcessor. BeanFactoryPostProcessor A BeanFactoryPostProcessor may interact with and modify bean definitions, but