[说明] 本程序中预设了若干个用户名和口令。用户输入正确的用户名后，可以查找对应的口令，一旦输入结束标记“end”，程序结束。[Java代码]import java. io. *:public class User {public String user;public Siring pass;public User() { }public User( String u,String p) { user=u; pass=p;}public String (1) () { return this. user; }public String (2) () { return this. pass; }public static void main(String[] args) { User ua[]={new User("Li","123456"), new User("wang","654321"), new User("Song","666666")}; while(true) { InputStreamReader reader = new InputStreamReader(System. in); BufferedReader inpul = new BnfferedReader(reader); System. out. print("Enter your name:"); String name = null; try { name = input. readLine();} catch (IOException ex) {} if( (3) ) break; int i; for (i=0;i＜3;i++) { if (name. equals(ua[i]. getUser())){ System. out. println("密码:"+ua[i].getPass()); (4) ; } } if ( (5) ) System. out. println("该用户不存在!"); } }}