public class Credit

public class Credit {
String cardNum;
String password;

public Credit(String cardNum, String password) {
    this.cardNum = cardNum;
    this.password = password;
    if (password.equals("123456")) {
        System.out.println("信用卡" + cardNum + "的默认密码为" + password);
    } else {
        System.out.println("重置信用卡" + cardNum + "的密码为" + password);
    }
}

public Credit(String cardNum) {
    this(cardNum, "123456");
}

public static void main(String[] args) {
    Credit initialCredit = new Credit("4013735633800642");
    Credit resetedCredit = new Credit("4013735633800642", "168779");
}

}