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Finding all classes that extend a base class
Roberto Gentili edited this page Oct 13, 2021
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24 revisions
To find all classes that extend a base class we are going to use the ClassHunter and, in the following example, we look for all classes who extends java.util.AbstractList:
import java.util.AbstractList;
import java.util.Collection;
import org.burningwave.core.assembler.ComponentContainer;
import org.burningwave.core.assembler.ComponentSupplier;
import org.burningwave.core.classes.ClassCriteria;
import org.burningwave.core.classes.ClassHunter;
import org.burningwave.core.classes.SearchConfig;
import org.burningwave.core.io.PathHelper;
public class Finder {
public Collection<Class<?>> find() {
ComponentSupplier componentSupplier = ComponentContainer.getInstance();
PathHelper pathHelper = componentSupplier.getPathHelper();
ClassHunter classHunter = componentSupplier.getClassHunter();
SearchConfig searchConfig = SearchConfig.forPaths(
//Here you can add all absolute path you want:
//both folders, zip and jar will be recursively scanned.
//For example you can add: "C:\\Users\\user\\.m2"
//With the line below the search will be executed on runtime Classpaths
//(see https://github.com/burningwave/core/wiki/In-depth-look-to-ClassHunter-and-configuration-guide)
pathHelper.getMainClassPaths()
).by(
ClassCriteria.create().byClassesThatMatch((uploadedClasses, currentScannedClass) ->
//[1]here you recall the uploaded class by "useClasses" method. In this case we find all class who extends java.util.AbstractList
uploadedClasses.get(AbstractList.class).isAssignableFrom(currentScannedClass)
).useClasses(
//With this directive we ask the library to load one or more classes to be used for comparisons:
//it serves to eliminate the problem that a class, loaded by different class loaders,
//turns out to be different for the comparison operators (eg. The isAssignableFrom method).
//If you call this method, you must retrieve the uploaded class in all methods that support this feature like in the point[1]
AbstractList.class
)
);
try (ClassHunter.SearchResult searchResult = classHunter.findBy(searchConfig)) {
return searchResult.getClasses();
}
}
}
Burningwave core is a fully indipendent, advanced, free and open source Java frameworks building library that contains AN EXTREMELY POWERFUL CLASSPATH SCANNER.
To include Burningwave Core library in your projects simply use with Apache Maven:
<dependency>
<groupId>org.burningwave</groupId>
<artifactId>core</artifactId>
<version>12.65.2</version>
</dependency>
To use Burningwave Core as a Java module add the following to your module-info.java
:
requires org.burningwave.core;
ClassFactory
ClassHunter
- In depth look to and configuration guide
- USE CASE: retrieving all classes of the classpath
- USE CASE: retrieving all classes that implement one or more interfaces
- USE CASE: finding all classes that extend a base class
- USE CASE: searching for all classes that have package name that matches a regex
- USE CASE: finding all classes for module name (Java 9 and later)
- USE CASE: finding all annotated classes
- USE CASE: how to scan classes for specific annotations and collect its values
- USE CASE: searching for all classes with a constructor that takes a specific type as first parameter and with at least 2 methods that begin for a given string
- USE CASE: searching for all classes with methods whose name begins for a given string and that takes a specific type as its first parameter
- USE CASE: finding all classes that have at least 2 protected fields