Question

请参考以下代码

public class Account {

    private String firstName;
    private String lastName;
    private int accountNumber;
    private int apin;
    private double abalance;

    public Account(String fname, String lname, int anumber, int pin,
            double balance) {
        fname = firstName;
        lname = lastName;
        anumber = accountNumber;
        pin = apin;
        balance = abalance;

        System.out.println("variables set");
    }

    public String getfirstName() {
        return firstName;
    }

    public String getlastName() {
        return lastName;
    }

    public int getaccountNumber() {
        return accountNumber;
    }

    public int getpin() {
        return apin;
    }

    public double getbalance() {
        return abalance;
    }

}

public class bank {

    private Account[] account;
    boolean flag = false;
    Account returnAccount;

    public Account bank(int anum, int pin) {
        account = new Account[3];
        account[0] = new Account("Steve", "Kom", 1234, 333, 50000);
        account[1] = new Account("Mack", "Dumbo", 2345, 123, 80000);
        account[2] = new Account("Xina", "Patt", 2145, 222, 40000);

        System.out.println(account[0].getaccountNumber());

        for (Account aa : account) {
            System.out.println(aa.getaccountNumber());
        }

        return returnAccount;
    }
}

在上面的代码中，get方法总是返回0，为什么变量没有设置。我很困惑我做错了什么。

Answer 1

构造函数中的赋值语法错误：

public Account(String fname, String lname, int anumber, int pin,
        double balance) {
    fname = firstName; //incorrect assignment
    lname = lastName; //incorrect assignment
    anumber = accountNumber; //incorrect assignment
    pin = apin; //incorrect assignment
    balance = abalance; //incorrect assignment

    System.out.println("variables set");
}

应该是

public Account(String fname, String lname, int anumber, int pin, double balance) {
      firstName = fname; //switched - correct assignment
      lastName = lname ; //switched - correct assignment
      accountNumber = anumber; //switched - correct assignment
      apin = pin ; //switched - correct assignment
      abalance = balance; //switched - correct assignment

      System.out.println("variables set");
}

Answer 2

您在构造函数

中设置了错误的值

fname = firstName;

将其更改为

this.firstName  = fname;

Answer 3

public Account(String fname, String lname, int anumber, int pin,
    double balance) {
fname = firstName; // swap
lname = lastName; // swap
anumber = accountNumber; 
pin = apin;
balance = abalance;

System.out.println("variables set");
}

未在java代码中设置的变量

3 个答案: