ObjectAnalyzerTest.java Source code

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Here is the source code for ObjectAnalyzerTest.java

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/*
 This program is a part of the companion code for Core Java 8th ed.
 (http://horstmann.com/corejava)
    
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation, either version 3 of the License, or
 (at your option) any later version.
    
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
    
 You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

import java.lang.reflect.AccessibleObject;
import java.lang.reflect.Array;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.ArrayList;

/**
 * This program uses reflection to spy on objects.
 * 
 * @version 1.11 2004-02-21
 * @author Cay Horstmann
 */
public class ObjectAnalyzerTest {
    public static void main(String[] args) {
        ArrayList<Integer> squares = new ArrayList<Integer>();
        for (int i = 1; i <= 5; i++)
            squares.add(i * i);
        System.out.println(new ObjectAnalyzer().toString(squares));
    }
}

class ObjectAnalyzer {
    /**
     * Converts an object to a string representation that lists all fields.
     * 
     * @param obj
     *          an object
     * @return a string with the object's class name and all field names and
     *         values
     */
    public String toString(Object obj) {
        if (obj == null)
            return "null";
        if (visited.contains(obj))
            return "...";
        visited.add(obj);
        Class cl = obj.getClass();
        if (cl == String.class)
            return (String) obj;
        if (cl.isArray()) {
            String r = cl.getComponentType() + "[]{";
            for (int i = 0; i < Array.getLength(obj); i++) {
                if (i > 0)
                    r += ",";
                Object val = Array.get(obj, i);
                if (cl.getComponentType().isPrimitive())
                    r += val;
                else
                    r += toString(val);
            }
            return r + "}";
        }

        String r = cl.getName();
        // inspect the fields of this class and all superclasses
        do {
            r += "[";
            Field[] fields = cl.getDeclaredFields();
            AccessibleObject.setAccessible(fields, true);
            // get the names and values of all fields
            for (Field f : fields) {
                if (!Modifier.isStatic(f.getModifiers())) {
                    if (!r.endsWith("["))
                        r += ",";
                    r += f.getName() + "=";
                    try {
                        Class t = f.getType();
                        Object val = f.get(obj);
                        if (t.isPrimitive())
                            r += val;
                        else
                            r += toString(val);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }
            r += "]";
            cl = cl.getSuperclass();
        } while (cl != null);

        return r;
    }

    private ArrayList<Object> visited = new ArrayList<Object>();
}