小型银行存取代码

/////// BankAccount.java /////// public class BankAccount // class name { public BankAccount(String id, String ss, double amt) // constructor { acct_no = id; owner = ss; acct_bal = (amt > 0) ? amt : 0.0; } public double balance() { return acct_bal; } public void deposit(double amt) { if ( amt > 0 ) acct_bal += amt; } public boolean withdraw(double amt) { if ( amt <=0 || amt > acct_bal ) return false; // failure acct_bal -= amt; return true; // success } public String id() { return acct_no; } public String owner() { return owner; } public String toString() { return acct_no + ":" + owner + ":" + acct_bal; } private String acct_no; // account number private String owner; // owner ss private double acct_bal; // current balance }