一种通用的toString()方法的编写

package com.corejava.reflection;

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

public class ObjectAnalyzer {

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

public String toString(Object obj) {
if (obj == null)
return null;
if (visited.contains(obj))
return "...";
visited.add(obj);
Class c1 = obj.getClass();
if (c1 == String.class)
return (String) obj;
if (c1.isArray()) {
String r = c1.getComponentType() + "[]{";
for (int i = 0; i < Array.getLength(obj); i++) {
if (i > 0)
r += ",";
Object val = Array.get(obj, i);
if (c1.getComponentType().isPrimitive())
r += val;
else
r += toString(val);
}
return r + "}";
}
String r = c1.getName();
do {
r += "[";
Field[] fields = c1.getDeclaredFields();
AccessibleObject.setAccessible(fields, true);
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 += "]";
c1 = c1.getSuperclass();
} while (c1 != null);
return r;
}
}

package com.corejava.reflection;

import java.util.ArrayList;

public class ObjectAnalyzerTest {

public static void main(String[] args) {
ArrayList<Integer> squares = new ArrayList<>();
for (int i = 1; i < 5; i++)
squares.add(i * i);
System.out.println(new ObjectAnalyzer().toString(squares));
}
}

java.util.ArrayList[elementData=class java.lang.Object[]{java.lang.Integer[value=1][][],java.lang.Integer[value=4][][],java.lang.Integer[value=9][][],java.lang.Integer[value=16][][],null,null,null,null,null,null},size=4][modCount=4][][]