Invoking and handling privates and all other methods of an object with and without the use of Reflection in Java

For methods handling we are going to use Methods component; Methods component uses to cache all methods and all method handles for faster access. In order to accomplish the task, we initially need to add the following dependency to our pom.xml:

Let’s take a look at the code now:

import static org.burningwave.core.assembler.StaticComponentContainer.Classes;
import static org.burningwave.core.assembler.StaticComponentContainer.Methods;

import java.lang.invoke.MethodHandle;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;
import java.security.ProtectionDomain;
import java.util.Collection;

import org.burningwave.core.classes.MethodCriteria;


@SuppressWarnings("unused")
public class MethodsHandler {

    public static void execute() {
        //Invoking method by using reflection
        Methods.invoke(System.out, "println", "Hello World");

        //Invoking static method by using MethodHandle
        Integer number = Methods.invokeStaticDirect(Integer.class, "valueOf", 1);

        //Invoking method by using MethodHandle
        Methods.invokeDirect(System.out, "println", number);

        //Filtering and obtaining a MethodHandle reference
        MethodHandle methodHandle = Methods.findFirstDirectHandle(
            MethodCriteria.byScanUpTo((cls) ->
            //We only analyze the ClassLoader class and not all of its hierarchy (default behavior)
                cls.getName().equals(ClassLoader.class.getName())
            ).name(
                "defineClass"::equals
            ).and().parameterTypes(params -> 
                params.length == 3
            ).and().parameterTypesAreAssignableFrom(
                String.class, ByteBuffer.class, ProtectionDomain.class
            ).and().returnType((cls) -> 
                cls.getName().equals(Class.class.getName())
            ), ClassLoader.class
        );        

        //Filtering and obtaining all methods of ClassLoader class that have at least
        //one input parameter of Class type
        Collection<Method> methods = Methods.findAll(
            MethodCriteria.byScanUpTo((cls) ->
                //We only analyze the ClassLoader class and not all of its hierarchy (default behavior)
                cls.getName().equals(ClassLoader.class.getName())
            ).parameter((params, idx) -> {
                return Classes.isAssignableFrom(params[idx].getType(), Class.class);
            }), ClassLoader.class
        );
    }

    public static void main(String[] args) {
        execute();
    }

}

We learned how to handle methods and the complete source is available here.

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Invoking and handling privates and all other methods of an object with and without the use of Reflection in Java

Roberto Gentili

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