corejava第10版

corejava第10版/v1ch05/objectAnalyzer/ObjectAnalyzer.java

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+package objectAnalyzer;
+
+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<>();
+
+   /**
+    * 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;
+   }
+}