java-lang Archives - Programming for fun and profit

Java Lang Tutorial

Jun 18, 2016 Posted by farenda Java 0 comments

In Java Lang Tutorial you will learn handy features of classes from java.lang package!

Java Lang Classes

Java Objects equals hashcode
Shows how to use (new in Java 7) Objects to implement equals and hashcode.
Java null check
Shows how to validate input using (new in Java 7) Objects class.
Java external process
How to run external process from Java.
Java System properties
Shows how to work with system properties.

Reflection

Java find annotated classes
Learn how to find annotated classes in Java.
Java Reflection Generic Type
Find out how to get generic type parameter using reflection!
Java reflection annotated fields/methods
Shows how to find annotated fields and/or methods using Reflection.

Java Lang Exceptions

Java UnsupportedClassVersionError
Unsupported major.minor version sounds familiar?

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Java find annotated classes

Aug 25, 2015 Posted by farenda Java 0 comments

Problem:

How to find annotated classes in Java? JDK by itself doesn’t provide such mechanism, but there are libraries that can do that. One of them is Reflections, which is used in the following example.

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Spring find annotated classes

Aug 24, 2015 Posted by farenda Spring Framework 0 comments

Problem:

How to find annotated classes using Spring and read metadata from them? Sometimes you may want to attach metadata to your classes using custom annotations. Here’s an example how you can leverage Spring‘s classpath scanning mechanism to do that.

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Java reflection annotated fields/methods

Aug 21, 2015 Posted by farenda Java 0 comments

Problem:

How to use Java Reflection to find annotated fields and/or methods? java.lang.reflect provides means to do it fairly easily as can be seen in the following example.

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Java Reflection Generic Type

Aug 20, 2015 Posted by farenda Java 0 comments

Problem:

How to get Java generic type parameter using reflection in runtime? Java doesn’t make it easy with type erasure, but it’s possible. See how.

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