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確定。所以情況就是這樣。在我的課堂中有一個calculateTax方法，如下所示。變化領域的可回收局部變量在if語句
但我意識到，我已經犯了大錯。實際上，在課程開始時，「稅收」就是作爲一個領域創造的。
private double tax;
這實際上應該是一個變量！
但是，當我創建它作爲方法的局部變量public double calculateTax(double tax)它的工作原理，但是當我跑我的測試反對他們失敗了。我得到的消息
The method calculateTax(double) in the type Salary is not applicable for the arguments()
所以我要去哪裏錯了？
如何建立稅收變量（仍然可以退還）不改變方法的名稱？ 「calculateTax」方法需要保持原樣。那麼我在哪裏以及如何創建「稅收」變量？提前致謝！
public double calculateTax() {
if (this.salary <= personalAllowance) { // If the salary is less
// £9440 (personal allowance) and below then no tax will be applied.
}
else if (this.salary <= taxThreshold) { // Else if the salary is less than or equal to the
// tax threshold then do the following:
double taxableSalary = this.salary - personalAllowance; // Salary take away the personal allowance
// equals the taxable salary.
this.tax = taxableSalary * 0.2; // The tax equal the taxable salary * 0.2 (20%)
}
else if (this.salary > 32010) {
double basicRate = taxThreshold * 0.2; // The basic rate tax is the tax threshold * 0.2
double difference = this.salary - taxThreshold; // The difference is the salary - the tax threshold
double highTax = difference - personalAllowance; // The high tax to be calculated is the difference
// take away personal allowance.
double highRate = highTax * 0.4; // The high rate tax is the high tax * the high tax value (40%)
this.tax = highRate + basicRate; // Total tax is the high rate tax (40%) + the basic rate tax (20%)
}
return tax;