舍入雙的Java

Question

public class project3 { 
    public static void main(String[] args) { 

     int earnedRuns = 52; 
     int inningsPitched = 182; 
     double ERA = (earnedRuns * 9)/inningsPitched; 
     String FirstName = "Anibal"; 
     String LastName = "Sanchez"; 

     System.out.println("Pitcher's first name: " + FirstName); 
     System.out.println("Pitcher's last name: " + LastName); 
     System.out.println("Number of earned runs: " + earnedRuns); 
     System.out.println("Number of innings pitched: " + inningsPitched); 
     System.out.println(FirstName + " " + LastName + " has an ERA of " + ERA); 
    } 
} 

時代出來爲2.0不2.57 ... ECT 我想不通爲什麼

Answer 1

Baically你：

1. 由乘以一個整數整數→整數（結果：486）
2. 除以一個整數由整數 - >整數（結果：2）
3. 分配結果到雙變量 - >雙（結果：2.0D）

所以你首先需要轉換（「轉換」）這些整數浮動或雙打。

double ERA = ((double)earnedRuns * 9)/inningsPitched; 

或簡單：

double ERA = (earnedRuns * 9.0)/inningsPitched; 

這足以投只是一個整數，因爲在Java：整數*雙 - >雙

編輯：

9.0 d或9.0 d只是告訴java明確表示9.0意味着是一個double。 同樣適用於9.0 f或9.0 F。這意味着9.0是一個float。