返回值顯示爲0.0。爲什麼這樣？

Question

public class employee { 

String empname; 
    int empcode ; 
    double basicpay; 

    employee() 
    { 
     empname  = ""; 
     empcode  = 0; 
     basicpay  = 0.0; 
    } 
    employee(String n , int p , double q) 
    { 
     n = empname; 
     p = empcode; 
     q = basicpay; 
    } 
    double salarycal() 
    { 
     double salary,hra,da,allowance,totalsalary;allowance = 0;totalsalary = 0; 
     hra = 0.3*basicpay; 
     da = 0.4*basicpay; 
     salary = basicpay + hra + da; 
     if(empcode<=15 && salary<=15000) 
     { 
      allowance = 0.2*salary; 
      if (allowance> 2500) 

      allowance = allowance - (allowance-2500); 
     } 
     else 
     { 
      allowance = 1000; 
     } 
     totalsalary =salary + allowance; 

     return totalsalary;//the problem is that the total salary is not returned. 
    } 
} 

請告訴該程序必須進行哪些更正。

Answer 1

我相信你的構造函數的一個向後做任務。它應該看起來像：

employee(String n , int p , double q) 
{ 
    empname = n; 
    empcode = p; 
    basicpay = q; 
} 

Answer 2

它工作正常，因爲你用0乘以所有東西。

hra = 0.3*basicpay; // basicpay is 0. so 0. 
da = 0.4*basicpay; // basicpay is 0. so 0. 
salary = basicpay + hra + da; // 0+0+0 = 0 

指定一個非零值到basicpay。在你的構造函數中，你已經交換了參數和字段。如果您使用的是this錯誤是顯而易見的，像

employee(String n , int p , double q) 
    // n = empname; 
    // p = empcode; 
    // q = basicpay; 
    this.empname = n; 
    this.empcode = p; 
    this.basicpay = q; 
} 

此外，類名（按照約定）應該以大寫字母開頭; Employee。

Answer 3

默認構造 在默認的構造函數要初始化爲零，basicpay = 0.0，你被它這樣的答案是零乘一切。

參數化的構造在參數化的構造函數中要指定值錯誤

employee(String n , int p , double q) 
    { 
     n = empname; 
     p = empcode; 
     q = basicpay; 
    } 

basicpay是double即默認值是0.0所以它也會給你的結果爲零。

修改後的代碼：

employee(String n , int p , double q) { 
    this.empname = n; 
    this.empcode = p; 
    this.basicpay = q; 
}