Given an object and a class, return all the fields in that class and any object that it contains which are of that class (used only in testing, this should not be in the shipped product). - Android java.lang.reflect

Android examples for java.lang.reflect:Field

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Description

Given an object and a class, return all the fields in that class and any object that it contains which are of that class (used only in testing, this should not be in the shipped product).

Demo Code

/**//from  ww w.j  a va 2  s .  c o  m
 * utilities to access and set fields in objects via reflection
 * @author Matthew
 * Copyright (c) 2013 Visible Automation LLC.  All Rights Reserved.
 */
//package com.java2s;
import java.lang.reflect.Field;

import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

public class Main {
    /**
     * Given an object and a class, return all the fields in that class and any object that it contains which
     * are of that class (used only in testing, this should not be in the shipped product).  
     * It uses a "breadcrumb trail" to prevent circular references, but I've not tested it in practices
     * @param o
     * @param c
     * @return
     * @throws IllegalAccessException
     */
    public static List<String> getMatchingFieldsByTypeRecursively(Object o,
            Class c) throws IllegalAccessException {
        Stack<Class> breadcrumb = new Stack<Class>();
        breadcrumb.push(o.getClass());
        List<String> result = new ArrayList<String>();
        getMatchingFieldsByTypeRecursively(o, o.getClass(), c, breadcrumb,
                result);
        return result;
    }

    public static void getMatchingFieldsByTypeRecursively(Object o,
            Class objectClass, Class c, Stack<Class> breadcrumb,
            List<String> result) throws IllegalAccessException {
        while ((objectClass != null) && (objectClass != Object.class)) {
            Field fields[] = objectClass.getDeclaredFields();
            for (Field field : fields) {
                if (field.getType() == c) {
                    result.add(getFieldPath(breadcrumb, field));
                } else if (!field.getType().isPrimitive()
                        && (field.getType() != String.class)) {
                    field.setAccessible(true);
                    Object fieldValue = field.get(o);
                    if ((fieldValue != null)
                            && !inBreadcrumb(breadcrumb, field.getType())) {
                        breadcrumb.push(field.getType());
                        getMatchingFieldsByTypeRecursively(fieldValue,
                                field.getType(), c, breadcrumb, result);
                        breadcrumb.pop();
                    }
                }
            }
            objectClass = objectClass.getSuperclass();
        }
    }

    public static String getFieldPath(Stack<Class> breadcrumb, Field field) {
        StringBuffer sb = new StringBuffer();
        for (int i = breadcrumb.size() - 1; i >= 0; i--) {
            Class c = breadcrumb.get(i);
            sb.append(c.getCanonicalName());
            sb.append('.');
        }
        sb.append(field.getName());
        return sb.toString();
    }

    public static boolean inBreadcrumb(Stack<Class> breadcrumb, Class c) {
        for (Class cCand : breadcrumb) {
            if (cCand == c) {
                return true;
            }
        }
        return false;
    }
}

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