objectinspectortest.java

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/**
   @version 1.02 2004-08-21
   @author Cay Horstmann
*/

import java.awt.*;
import java.awt.event.*;
import java.lang.reflect.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;
import javax.swing.tree.*;

/**
   This program demonstrates how to use a custom tree
   model. It displays the fields of an object.
*/
public class ObjectInspectorTest
{  
   public static void main(String[] args)
   {  
      JFrame frame = new ObjectInspectorFrame();
      frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
      frame.setVisible(true);
   }
}

/**
   This frame holds the object tree. 
*/
class ObjectInspectorFrame extends JFrame
{  
   public ObjectInspectorFrame()
   {  
      setTitle("ObjectInspectorTest");
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      // we inspect this frame object

      Variable v = new Variable(getClass(), "this", this);
      ObjectTreeModel model = new ObjectTreeModel();
      model.setRoot(v);

      // construct and show tree

      tree = new JTree(model);
      add(new JScrollPane(tree), BorderLayout.CENTER);
   }

   private JTree tree;
   private static final int DEFAULT_WIDTH = 400;
   private static final int DEFAULT_HEIGHT = 300;
}

/**
   This tree model describes the tree structure of a Java
   object. Children are the objects that are stored in instance
   variables.
*/
class ObjectTreeModel implements TreeModel
{ 
   /**
      Constructs an empty tree.
   */
   public ObjectTreeModel()
   {  
      root = null;
   }

   /**
      Sets the root to a given variable.
      @param v the variable that is being described by this tree
   */
   public void setRoot(Variable v)
   {  
      Variable oldRoot = v;
      root = v;
      fireTreeStructureChanged(oldRoot);
   }

   public Object getRoot()
   {  
      return root;
   }

   public int getChildCount(Object parent)
   {  
      return ((Variable) parent).getFields().size();
   }

   public Object getChild(Object parent, int index)
   {  
      ArrayList<Field> fields = ((Variable) parent).getFields();
      Field f = (Field) fields.get(index);
      Object parentValue = ((Variable) parent).getValue();
      try
      {  
         return new Variable(f.getType(), f.getName(), f.get(parentValue));
      }
      catch (IllegalAccessException e)
      {  
         return null;
      }
   }

   public int getIndexOfChild(Object parent, Object child)
   {  
      int n = getChildCount(parent);
      for (int i = 0; i < n; i++)
         if (getChild(parent, i).equals(child))
            return i;
      return -1;
   }

   public boolean isLeaf(Object node)
   {  
      return getChildCount(node) == 0;
   }

   public void valueForPathChanged(TreePath path, 
      Object newValue)
   {}

   public void addTreeModelListener(TreeModelListener l)
   {  
      listenerList.add(TreeModelListener.class, l);
   }

   public void removeTreeModelListener(TreeModelListener l)
   {  
      listenerList.remove(TreeModelListener.class, l);
   }

   protected void fireTreeStructureChanged(Object oldRoot)
   {  
      TreeModelEvent event = new TreeModelEvent(this, new Object[] {oldRoot});
      EventListener[] listeners = listenerList.getListeners(TreeModelListener.class);
      for (int i = 0; i < listeners.length; i++)
         ((TreeModelListener) listeners[i]).treeStructureChanged(event);
   }

   private Variable root;
   private EventListenerList listenerList = new EventListenerList();
}

/**
   A variable with a type, name, and value.
*/
class Variable
{ 
   /**
      Construct a variable
      @param aType the type
      @param aName the name
      @param aValue the value
   */
   public Variable(Class aType, String aName, Object aValue)
   {  
      type = aType;
      name = aName;
      value = aValue;
      fields = new ArrayList<Field>();

      // find all fields if we have a class type except we don't expand strings and null values

      if (!type.isPrimitive() && !type.isArray() && !type.equals(String.class) && value != null)
      {  
         // get fields from the class and all superclasses
         for (Class c = value.getClass(); c != null; c = c.getSuperclass())
         {  
            Field[] fs = c.getDeclaredFields();
            AccessibleObject.setAccessible(fs, true);

            // get all nonstatic fields
            for (Field f : fs)
               if ((f.getModifiers() & Modifier.STATIC) == 0)
                  fields.add(f);
         }
      }
   }

   /**
      Gets the value of this variable.
      @return the value
   */
   public Object getValue() { return value; }

   /**
      Gets all nonstatic fields of this variable.
      @return an array list of variables describing the fields
   */
   public ArrayList<Field> getFields() { return fields; }

   public String toString()
   {  
      String r = type + " " + name;
      if (type.isPrimitive()) r += "=" + value;
      else if (type.equals(String.class)) r += "=" + value;
      else if (value == null) r += "=null";
      return r;
   }

   private Class type;
   private String name;
   private Object value;
   private ArrayList<Field> fields;
}