当有一座小桥，每次只能通过一个人，如果同时有两个人在桥上，桥会断开如今有三个姓和名的首字母相同的人多次通过此桥

package com.quest.mchen2.thread.single_thread_execution;public class Gate {           private int counter=0;      private String name= "Nobody";      private String address= "Nowhere";           //为了防止多线程情况下对象先后交叉执行，从而导致将共享实例的字段改写了      public synchronized void pass(String name, String address){            this. counter++;            this. name=name;            this. address=address;            check();     }           @Override      public synchronized String toString() {            // TODO Auto-generated method stub            return "No."+ counter+ ":"+ name+ ", "+ address;     }           private void check(){            if( name.charAt(0)!= address.charAt(0)){                System. out.println( "*****BROKEN*****" +toString());           }     }}package com.quest.mchen2.thread.single_thread_execution;public class UserThread extends Thread{      private final Gate gate;      private final String myname;      private final String myaddress;           public UserThread(Gate gate, String myname, String myaddress){            this. gate=gate;            this. myname=myname;            this. myaddress=myaddress;     }           @Override      public void run() {            // TODO Auto-generated method stub           System. out.println( myname+ " BEGIN");            while( true){                 gate. pass( myname, myaddress);           }     }     }package com.quest.mchen2.thread.single_thread_execution;public class Main {      /**      * @param args      */      public static void main(String[] args) {            // TODO Auto-generated method stub                      System. out.println( "Testing Gate, hit CTRL+C to exit");           Gate gate= new Gate();            new UserThread(gate, "Alice", "Alaska").start();            new UserThread(gate, "Bobby", "Brazil").start();            new UserThread(gate, "Chris", "Canada").start();     }}