Class reflection to get class name, type variables, interfaces, annotation - Java Reflection

Java examples for Reflection:Class

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Description

Class reflection to get class name, type variables, interfaces, annotation

Demo Code

import java.lang.annotation.Annotation;
import java.lang.reflect.Modifier;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import static java.lang.System.out;

public class ClassDeclarationSpy {
    public static void main(String... args) {
        try {//  w w  w  .java 2s.  com
            Class<?> c = Class.forName(args[0]);
            out.format("Class:%n  %s%n%n", c.getCanonicalName());
            out.format("Modifiers:%n  %s%n%n",
                    Modifier.toString(c.getModifiers()));

            out.format("Type Parameters:%n");
            TypeVariable[] tv = c.getTypeParameters();
            if (tv.length != 0) {
                out.format("  ");
                for (TypeVariable t : tv)
                    out.format("%s ", t.getName());
                out.format("%n%n");
            } else {
                out.format("  -- No Type Parameters --%n%n");
            }

            out.format("Implemented Interfaces:%n");
            Type[] intfs = c.getGenericInterfaces();
            if (intfs.length != 0) {
                for (Type intf : intfs)
                    out.format("  %s%n", intf.toString());
                out.format("%n");
            } else {
                out.format("  -- No Implemented Interfaces --%n%n");
            }

            out.format("Inheritance Path:%n");
            List<Class> l = new ArrayList<Class>();
            printAncestor(c, l);
            if (l.size() != 0) {
                for (Class<?> cl : l)
                    out.format("  %s%n", cl.getCanonicalName());
                out.format("%n");
            } else {
                out.format("  -- No Super Classes --%n%n");
            }

            out.format("Annotations:%n");
            Annotation[] ann = c.getAnnotations();
            if (ann.length != 0) {
                for (Annotation a : ann)
                    out.format("  %s%n", a.toString());
                out.format("%n");
            } else {
                out.format("  -- No Annotations --%n%n");
            }

            // production code should handle this exception more gracefully
        } catch (ClassNotFoundException x) {
            x.printStackTrace();
        }
    }

    private static void printAncestor(Class<?> c, List<Class> l) {
        Class<?> ancestor = c.getSuperclass();
        if (ancestor != null) {
            l.add(ancestor);
            printAncestor(ancestor, l);
        }
    }
}

/*
 * Copyright (c) 1995, 2008, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

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