无法对非静态字段进行静态引用

9o685dep 于 2021-06-30 发布在 Java

关注(0)|答案(6)|浏览(479)

如果这段代码格式不正确，我会提前道歉，尝试粘贴而不是重新键入每一行。如果它不正确，有人能告诉我一个简单的方法粘贴多行代码一次？
我的主要问题是，我不断收到一条错误消息，指出： Cannot make a static reference to the non-static field balance. 我尝试过使方法成为静态的，没有结果，并通过从头中删除“static”使main方法成为非静态的，但是我得到了以下消息： java.lang.NoSuchMethodError: main Exception in thread "main" 有人有什么想法吗？感谢您的帮助。

public class Account {

    public static void main(String[] args) {
        Account account = new Account(1122, 20000, 4.5);

        account.withdraw(balance, 2500);
        account.deposit(balance, 3000);
        System.out.println("Balance is " + account.getBalance());
        System.out.println("Monthly interest is " + (account.getAnnualInterestRate()/12));
        System.out.println("The account was created " + account.getDateCreated());
    }

    private int id = 0;
    private double balance = 0;
    private double annualInterestRate = 0;
    public java.util.Date dateCreated;

    public Account() {
    }

    public Account(int id, double balance, double annualInterestRate) {
        this.id = id;
        this.balance = balance;
        this.annualInterestRate = annualInterestRate;
    }

    public void setId(int i) {
        id = i;
    }

    public int getID() {
        return id;
    }

    public void setBalance(double b){
        balance = b;
    }

    public double getBalance() {
        return balance;
    }

    public double getAnnualInterestRate() {
        return annualInterestRate;
    }

    public void setAnnualInterestRate(double interest) {
        annualInterestRate = interest;
    }

    public java.util.Date getDateCreated() {
        return this.dateCreated;
    }

    public void setDateCreated(java.util.Date dateCreated) {
        this.dateCreated = dateCreated;
    }

    public static double withdraw(double balance, double withdrawAmount) {
        double newBalance = balance - withdrawAmount;
        return newBalance;
    }

    public static double deposit(double balance, double depositAmount) {
        double newBalance = balance + depositAmount;
        return newBalance;
    }   
}

Java

来源：https://stackoverflow.com/questions/65211925/how-do-i-apply-static-reference-to-non-static-fields-in-java

6条答案

按热度按时间

hsgswve41#

写下：

private static double balance = 0;

你也可以这样写：

private static int id = 0;
private static double annualInterestRate = 0;
public static java.util.Date dateCreated;

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a8jjtwal2#

如果你想的话，你可以保持你的取款和存款方法是静态的，但是你必须像下面的代码那样编写它。sb=期初余额，eb=期末余额。

Account account = new Account(1122, 20000, 4.5);

    double sB = Account.withdraw(account.getBalance(), 2500);
    double eB = Account.deposit(sB, 3000);
    System.out.println("Balance is " + eB);
    System.out.println("Monthly interest is " + (account.getAnnualInterestRate()/12));
    account.setDateCreated(new Date());
    System.out.println("The account was created " + account.getDateCreated());

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aoyhnmkz3#

台词

account.withdraw(balance, 2500);
account.deposit(balance, 3000);

您可能希望使取款和存款非静态，并让它修改余额

public void withdraw(double withdrawAmount) {
    balance = balance - withdrawAmount;
}

public void deposit(double depositAmount) {
    balance = balance + depositAmount;
}

并从调用中删除balance参数

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nlejzf6q4#

您试图直接从静态方法访问非静态字段，这在java中是不合法的。balance是一个非静态字段，因此可以使用对象引用访问它，也可以使其成为静态字段。

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093gszye5#

静态电话提取和存款是你的问题。账户提取（余额2500）；这行行不通，因为“balance”是account的一个示例变量。代码没有什么意义，取款/存款不会封装在account对象本身吗？所以撤军应该更像

public void withdraw(double withdrawAmount)
{
    balance -= withdrawAmount;
}

当然，根据你的问题，你可以在这里做额外的验证，以防止负平衡等。

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s4chpxco6#

main 是静态方法。它不能引用 balance ，这是一个属性（非静态变量）。 balance 只有通过对象引用（例如 myAccount.balance 或者 yourAccount.balance ). 但是当它通过类（例如 Account.balance （那是谁的余额？）
我对你的代码做了一些修改，这样它就可以编译了。

public static void main(String[] args) {
    Account account = new Account(1122, 20000, 4.5);
    account.withdraw(2500);
    account.deposit(3000);

以及：

public void withdraw(double withdrawAmount) {
    balance -= withdrawAmount;
}

public void deposit(double depositAmount) {
    balance += depositAmount;
}

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无法对非静态字段进行静态引用

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