Scan the classpath in Java: how to find all classes that have at least 2 protected fields

To find all classes that have at least 2 protected fields by using the ClassHunter, we need to initially add the following dependency to our pom.xml:

<dependency>
    <groupId>org.burningwave</groupId>
    <artifactId>core</artifactId>
    <version>12.64.3</version>
</dependency>

… And to use Burningwave Core as a Java module, add the following to your module-info.java:

requires org.burningwave.core;

And now let’s take a look at the code:

import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.Date;

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.FieldCriteria;
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();

        FieldCriteria fieldCriteria = FieldCriteria.forEntireClassHierarchy().allThoseThatMatch((field) -> {
            return Modifier.isProtected(field.getModifiers());
        }).result((foundFields) -> {
            return foundFields.size() >= 2;
        });
        
        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 class paths
            pathHelper.getMainClassPaths()
        ).by(
            ClassCriteria.create().byMembers(
                fieldCriteria
            ).useClasses(
                Date.class,
                Object.class
            )
        );

        try (ClassHunter.SearchResult searchResult = classHunter.findBy(searchConfig)) {

            //If you need all found fields unconment this
            //searchResult.getMembersFlatMap().values();

            return searchResult.getClasses();
        }
    }

}

Flexible

It’s possible to search classes by every criteria that your imagination can make by using lambda expressions

Optimized

Scan engine is highly optimized using direct allocated ByteBuffers to avoid heap saturation

Open

Burningwave core is an advanced free and open source Java library