不兼容的類型：意外的返回值

Question

我是新來的Java，並試圖返回在最後一行打印出佣金的價值。但我不斷收到不兼容的類型：意外的返回值錯誤。

import java.util.Scanner; 

    public class retail { 
    public static void main (String[] args){ 

    char code; 
    double commission; 
    String enumber; 
    double retail_price=0; 
    Scanner scan = new Scanner(System.in); 
    System.out.println("Enter employee number: "); 
    enumber= scan.nextLine(); 
    System.out.println("Enter retail price: "); 
    retail_price= scan.nextDouble(); 
    System.out.println("Enter code:"); 
    code=scan.next().charAt(0); 
    if (code == 'A'){ commission = (retail_price/100)*6;} 
    else if (code == 'a') {commission = (retail_price/100)*6;} 
    else if (code == 'B') {commission = (retail_price/100)*8;} 
    else if (code == 'b') {commission = (retail_price/100)*8;} 
    else if (code == 'C') {commission = (retail_price/100)*10;} 
    else if (code == 'c') {commission = (retail_price/100)*10;} 
    else{System.out.println("Invalid code");} 
    return commission; 
    System.out.println("Employee number: "+enumber); 
    System.out.println("Retail price: "+retail_price); 
    System.out.println("Commission: "+commission); 
    } 
} 

Answer 1

您不需要在main方法中返回值。只需在申報並取消退貨時將佣金初始化爲0即可。

double commission=0; 
String enumber; 
double retail_price=0; 
Scanner scan = new Scanner(System.in); 
System.out.println("Enter employee number: "); 
enumber= scan.nextLine(); 
System.out.println("Enter retail price: "); 
retail_price= scan.nextDouble(); 
System.out.println("Enter code:"); 
code=scan.next().charAt(0); 
if (code == 'A'){ commission = (retail_price/100)*6;} 
else if (code == 'a') {commission = (retail_price/100)*6;} 
else if (code == 'B') {commission = (retail_price/100)*8;} 
else if (code == 'b') {commission = (retail_price/100)*8;} 
else if (code == 'C') {commission = (retail_price/100)*10;} 
else if (code == 'c') {commission = (retail_price/100)*10;} 
else{System.out.println("Invalid code");} 
System.out.println("Employee number: "+enumber); 
System.out.println("Retail price: "+retail_price); 
System.out.println("Commission: "+commission); 
}} 

Answer 2

您正在返回主要method.so內部，因爲它顯示錯誤。如果你想返回值，你應該使用這樣，

private static double setValue(char code,double commission,double retail_price){ 
     if (code == 'A'){ commission = (retail_price/100)*6;} 
     else if (code == 'a') {commission = (retail_price/100)*6;} 
     else if (code == 'B') {commission = (retail_price/100)*8;} 
     else if (code == 'b') {commission = (retail_price/100)*8;} 
     else if (code == 'C') {commission = (retail_price/100)*10;} 
     else if (code == 'c') {commission = (retail_price/100)*10;} 
     else{System.out.println("Invalid code");} 
     return commission; 
    } 


     public static void main(String ...args){ 
      char code; 
      double commission = 0; 
      String enumber; 
      double retail_price=0; 
      Scanner scan = new Scanner(System.in); 
      System.out.println("Enter employee number: "); 
      enumber= scan.nextLine(); 
      System.out.println("Enter retail price: "); 
      retail_price= scan.nextDouble(); 
      System.out.println("Enter code:"); 
      code=scan.next().charAt(0); 
      commission = setValue(code, commission, retail_price); 
      System.out.println("Employee number: "+enumber); 
      System.out.println("Retail price: "+retail_price); 
      System.out.println("Commission: "+commission); 

     } 

注： 此程序不需要返回值。你可以在主要方法中做你的生意。

Answer 3

修復的問題： 類名不是大寫 佣金從未初始化 回報去除

import java.util.Scanner; 
// Classes should allways be capitalized 
public class Retail 
{ 
    public static void main (String[] args) 
    { 

     char code; 
     double commission = 0; 
     String enumber; 
     double retail_price=0; 
     Scanner scan = new Scanner(System.in); 
     System.out.println("Enter employee number: "); 
     enumber= scan.nextLine(); 
     System.out.println("Enter retail price: "); 
     retail_price= scan.nextDouble(); 
     // added user guidance of whats expected 
     System.out.println("Enter code: A,B,C"); 
     code=scan.next().charAt(0); 
     if (code == 'A'){ commission = (retail_price/100)*6;} 
     else if (code == 'a') {commission = (retail_price/100)*6;} 
     else if (code == 'B') {commission = (retail_price/100)*8;} 
     else if (code == 'b') {commission = (retail_price/100)*8;} 
     else if (code == 'C') {commission = (retail_price/100)*10;} 
     else if (code == 'c') {commission = (retail_price/100)*10;} 
     else{System.out.println("Invalid code");} 
     System.out.println("Employee number: "+enumber); 
     System.out.println("Retail price: "+retail_price); 
     System.out.println("Commission: "+commission); 
    } 
}