import java.lang.reflect.*; public class class_existence_check { public static void main(String argv[]) { String class_name = argv[0]; Class c; try { c = Class.forName(class_name); } catch(Throwable e) { System.out.println(class_name + " not found"); return; } System.out.println(class_name + " exists"); } }

import java.lang.reflect.*; public class class_hierarchy { static void print_hierarchy(Class c, String indent) { System.out.println(indent + c); Class superclass = c.getSuperclass(); Class[] ifaces = c.getInterfaces(); for (int i = 0; i < ifaces.length; i++) print_hierarchy(ifaces[i], indent + "| "); if(superclass != null) print_hierarchy(superclass, indent + "> "); } public static void main(String argv[]) { String class_name = argv[0]; Class c; try { c = Class.forName(class_name); } catch(Throwable e) { System.out.println(class_name + " not found"); return; } print_hierarchy(c, ""); } }

import java.lang.reflect.*; public class class_list_methods { public static void main(String argv[]) { String class_name = argv[0]; Class c; try { c = Class.forName(class_name); } catch(Throwable e) { System.out.println(class_name + " not found"); return; } System.out.println("Methods of " + class_name + ":"); Method m[] = c.getDeclaredMethods(); for (int i = 0; i < m.length; i++) System.out.println(m[i].toString()); } }

package www_blog_pl; public class Uid { public int id; public String name; public Uid(String id) { String sql = "SELECT id,name FROM users WHERE id=" + id; // Temporary solution this.id = Integer.parseInt(id); if(this.id == 1) { name = "jasiu"; } else if(this.id == 2) { name = "kasia"; } else { this.id = 0; name = "unknown"; } } };

package www_blog_pl; public class www { public static String main(Uid viewer) { return "

Welcome to the blog server, " + viewer.name; } public static String index() { return main(new Uid("0")); } public static String person(Uid target) { return "<p>This is " + target.name + "'s blog"; } public static String view_comment(Uid target, int thread_nr, int comment_nr) { String comment = "This is " + comment_nr + "th comment in " + target.name + "'s blog"; return comment; } public static String post_comment(Uid viewer, Uid target, int thread_nr) { return "<p>Please write the comment below<br><form><input type='submit'>"; } public static String post_comment_2(Uid viewer, Uid target, int thread_nr, String comment) { String sql = "INSERT INTO comments VALUES (" + target.id + "," + thread_nr + ",'" + comment + "')"; // add new comment to the data base return "<p>Thank you, " + viewer.name + ", for your input\n"; } };

package www_blog_pl; public class www { public static String[] main_paramnames() { String[] x={"viewer"}; return x; }; public static String main(Uid viewer) { return "<p>Welcome to the blog server, " + viewer.name; } public static String[] index_paramnames() { String[] x={}; return x; }; public static String index() { return main(new Uid("0")); } public static String[] person_paramnames() { String[] x={"target"}; return x; }; public static String person(Uid target) { return "<p>This is " + target.name + "'s blog"; } public static String[] view_comment_paramnames() { String[] x={"target", "thread_nr", "comment_nr"}; return x; }; public static String view_comment(Uid target, int thread_nr, int comment_nr) { String comment = "This is " + comment_nr + "th comment in " + target.name + "'s blog"; return comment; } public static String[] post_comment_paramnames() { String[] x={"viewer", "target", "thread_nr"}; return x; }; public static String post_comment(Uid viewer, Uid target, int thread_nr) { return "<p>Please write the comment below<br><form><input type='submit'>"; } public static String[] post_comment_2_paramnames() { String[] x={"viewer", "target", "thread_nr", "comment"}; return x; }; public static String post_comment_2(Uid viewer, Uid target, int thread_nr, String comment) { String sql = "INSERT INTO comments VALUES (" + target.id + "," + thread_nr + ",'" + comment + "')"; // add new comment to the data base return "<p>Thank you, " + viewer.name + ", for your input\n"; } };

import java.lang.reflect.*; import java.util.*; public class rails { static void call(Class c, Method m, Hashtable args) throws java.lang.Exception { Class param_types[] = m.getParameterTypes(); // Shouldn't be necessary Class gpn_a[] = {}; Object gpn_aa[] = {}; Method gpn = c.getMethod(m.getName() + "_paramnames", gpn_a); String param_names[] = (String[])gpn.invoke(null, gpn_aa); if(param_names.length != param_types.length) throw new Exception("Bad param info"); Object a[] = new Object[param_types.length]; for(int i=0; i<param_types.length; i++) { String arg = (String)args.get(param_names[i]); Class typ = param_types[i]; Object o; // Conversions if(typ == java.lang.String.class) o = arg; else if(typ == int.class) o = new Integer(arg); else { Class str_a[] = {java.lang.String.class}; Constructor cstr = typ.getConstructor(str_a); Object str_aa[] = {arg}; o = cstr.newInstance(str_aa); } a[i] = o; } // null obj, static methods only String s = (String)m.invoke(null, a); System.out.println(s); } public static void main(String argv[]) { String class_name = argv[0]; Class c; try { c = Class.forName(class_name); } catch(Throwable e) { System.out.println("<p>Error, wrong request"); return; } Hashtable args = new Hashtable(); // Hashtable<String,String> args.put("action", "index"); // default action for(int i=1; i<argv.length; i++) { String arg = argv[i]; int j = arg.indexOf('='); String key; String value; if(j != -1) { key = arg.substring(0, j); value = arg.substring(j+1, arg.length()); } else { key = arg; value = "true"; } args.put(key, value); } String action = (String)args.get("action"); Method m[] = c.getDeclaredMethods(); for (int i = 0; i < m.length; i++) { if(m[i].getName().equals(action)) { try { call(c, m[i], args); } catch (Throwable e) { System.out.println("<p>Error, wrong request"); e.printStackTrace(); } return; } } System.out.println("<p>Error, unknown action " + action); } }

public class Hello_bean implements java.io.Serializable { protected String world; public Hello_bean() { world = "world"; } public void hello() { System.out.println("Hello, " + world); } public void setWorld(String newWorld) { world = newWorld; } public String getWorld() { return world; } }

import java.beans.*; public class Account implements java.io.Serializable { VetoableChangeSupport ctrls = new VetoableChangeSupport(this); public synchronized void addVetoableChangeListener(VetoableChangeListener l) { ctrls.addVetoableChangeListener(l); } public synchronized void removeVetoableChangeListener(VetoableChangeListener l) { ctrls.removeVetoableChangeListener(l); } float balance = 100.0f; public float getBalance() { return balance; } public void setBalance(float newBalance) { try { ctrls.fireVetoableChange("balance", new Float(balance), new Float(newBalance)); balance = newBalance; } catch (PropertyVetoException e) { System.out.println("The change has been vetoed: " + e.getMessage()); } } }

class AccountUser implements Runnable { Account account; AccountUser(Account account) { this.account = account; Thread thr = new Thread(this); thr.start(); } public void run() { try { while (true) { // Spend 80% of time, save 20% of time if(Math.random() > 0.8) account.setBalance(account.getBalance() + 100.0f*(float)Math.random()); else account.setBalance(account.getBalance() - 100.0f*(float)Math.random()); Thread.sleep(500); } } catch (Exception e) { e.printStackTrace(); } } }

import java.beans.*; class AccountController implements VetoableChangeListener { public void vetoableChange(PropertyChangeEvent evt) throws PropertyVetoException { float new_balance = ((Float)evt.getNewValue()).floatValue(); if (new_balance < 0.0f) { throw(new PropertyVetoException("balance must be non-negative and " + new_balance + " is not", evt)); } else { System.out.println(evt.getPropertyName() + " changed to " + new_balance); } } }

class Bank { public static void main(String args[]) { Account account = new Account(); AccountUser account_user = new AccountUser(account); AccountController account_controller = new AccountController(); account.addVetoableChangeListener(account_controller); } }