Name: dgC58589 Date: 11/21/97


I use 'java BeanDumper frogbean.Frog' with the class
frogbean.Spots missing and I get

$javac BeanDumper.java
$javac frogbean.Frog.java
$ rm frogbean/Spots.class
$java BeanDumper frogbean.Frog
java.lang.NullPointerException
        at java.util.Hashtable.put(Hashtable.java)
        at java.beans.Introspector.getDeclaredMethods(Introspector.java:735)
        at java.beans.Introspector.getTargetEventInfo(Introspector.java:444)
        at java.beans.Introspector.getBeanInfo(Introspector.java:200)
        at java.beans.Introspector.getBeanInfo(Introspector.java:102)
        at BeanDumper.dump(BeanDumper.java:10)
        at BeanDumper.main(BeanDumper.java:95)

It should complain that the class Spots could not be loaded !!!

------- BeanDumper.java -------------------

// A method to introspect a Bean
import java.beans.*;
import java.lang.reflect.*;

public class BeanDumper {
  public static void dump(Class bean){
    BeanInfo bi = null;
    try {
      bi = Introspector.getBeanInfo(
        bean, java.lang.Object.class);
    } catch(IntrospectionException ex) {
      System.out.println("Couldn't introspect " +
        bean.getName());
      System.exit(1);
    }
    PropertyDescriptor properties[] =
      bi.getPropertyDescriptors();
    for(int i = 0; i < properties.length; i++) {
      Class p = properties[i].getPropertyType();
      System.out.println(
        "Property type:\n " + p.getName());
      System.out.println(
        "Property name:\n " +
        properties[i].getName());
      Method readMethod =
        properties[i].getReadMethod();
      if(readMethod != null)
        System.out.println(
          "Read method:\n " +
          readMethod.toString());
      Method writeMethod =
        properties[i].getWriteMethod();
      if(writeMethod != null)
        System.out.println(
          "Write method:\n " +
          writeMethod.toString());
      System.out.println("====================");
    }
    System.out.println("Public methods:");
    MethodDescriptor methods[] =
      bi.getMethodDescriptors();
    for(int i = 0; i < methods.length; i++)
      System.out.println(
        methods[i].getMethod().toString());
    System.out.println("======================");
    System.out.println("Event support:");
    EventSetDescriptor events[] =
      bi.getEventSetDescriptors();
    for(int i = 0; i < events.length; i++) {
      System.out.println("Listener type:\n " +
        events[i].getListenerType().getName());
      Method lm[] =
        events[i].getListenerMethods();
      for(int j = 0; j < lm.length; j++)
        System.out.println(
          "Listener method:\n " +
          lm[j].getName());
      MethodDescriptor lmd[] =
        events[i].getListenerMethodDescriptors();
      for(int j = 0; j < lmd.length; j++)
        System.out.println(
          "Method descriptor:\n " +
          lmd[j].getMethod().toString());
      Method addListener =
        events[i].getAddListenerMethod();
      System.out.println(
          "Add Listener Method:\n " +
        addListener.toString());
      Method removeListener =
        events[i].getRemoveListenerMethod();
      System.out.println(
        "Remove Listener Method:\n " +
        removeListener.toString());
      System.out.println("====================");
    }
  }
  // Dump the class of your choice:
  public static void main(String args[]) {
    if(args.length < 1) {
      System.err.println("usage: \n" +
        "BeanDumper fully.qualified.class");
      System.exit(0);
    }
    Class c = null;
    try {
      c = Class.forName(args[0]);
if (c == null)
        System.out.println("Class is null");
    } catch(ClassNotFoundException ex) {
      System.err.println(
        "Couldn't find " + args[0]);
      System.exit(0);
    }
    dump(c);
  }
} ///:~


--------- frogbean/Frog.java -----------
package frogbean;
import java.awt.*;
import java.awt.event.*;

class Spots {}

public class Frog {
  private int jumps;
  private Color color;
  private Spots spots;
  private boolean jmpr;
  public int getJumps() { return jumps; }
  public void setJumps(int newJumps) {
    jumps = newJumps;
  }
  public Color getColor() { return color; }
  public void setColor(Color newColor) {
    color = newColor;
  }
  public Spots getSpots() { return spots; }
  public void setSpots(Spots newSpots) {
    spots = newSpots;
  }
  public boolean isJumper() { return jmpr; }
  public void setJumper(boolean j) { jmpr = j; }
  public void addActionListener(
      ActionListener l) {
    //...
  }
  public void removeActionListener(
      ActionListener l) {
    // ...
  }
  public void addKeyListener(KeyListener l) {
    // ...
  }
  public void removeKeyListener(KeyListener l) {
    // ...
  }
  // An "ordinary" public method:
  public void croak() {
    System.out.println("Ribbet!");
  }
} ///:~

(Review ID: 20426)
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