我想轉換多個指標使用方法，我卡住我不知道下一步該怎麼做？

Question

我在這裏有我的代碼這是一個混亂，我知道，但我與我的邏輯混淆，需要幫助，試圖讓這一起。所以，任何幫助表示讚賞。我想輸出是這個 「

轉換工具

1.Gallons到升

升至加侖

茶匙毫升

毫升至茶匙

請選擇轉換類型，你想作：1

請輸入加侖：5

總升是18.925"

import java.util.Scanner; 
public class ConversionProgram { 

public static final double LT_TO_GAL = .274; 
public static final double GAL_TO_LT = 3.785;   
public static final double TSP_TO_ML = 4.9289; 
public static final double ML_TO_TSP = .202; 


public static void main(String[] args) { 
    int nInitLit = 0;      
    int nInitGal = 0;      
    int nTotalLit = 0; 
    double dResult = 0; 
    double dNumber1 = 0; 
    double dNumber2 = 0; 
    int nPrice = 0; 
    double dTotalGal = 0.0;    
    Scanner input = new Scanner(System.in); 

    System.out.println("CONVERSION TOOL: "); 
    System.out.println("1. Gallons to liters "); 
    System.out.println("2. Liters to gallons"); 
    System.out.println("3. Teaspoons to milliliters"); 
    System.out.println("4. Milliliters to teaspoons"); 
    System.out.print(""); 

    System.out.print("Please select the type of conversion you would like to make: "); 
     int nConversion = input.nextInt(); 

    if (nConversion == 1) {   
     System.out.print("Please enter the gallons: "); 
     double dGal = input.nextDouble(); 

    } 

     else if (nConversion == 2) { 
      System.out.print("Please enter the total liters: ");    
      double dLit = input.nextDouble(); 
     } 

     else if (nConversion == 3) { 
      System.out.print("Please enter the total teaspoons "); 
      double dTsp = input.nextDouble();   
     } 

     else if (nConversion == 4) { 
      System.out.print("Please enter the total milliliters "); 
      double dMil = input.nextDouble();    
     } 


} //end main method 

public static double calculateGallonsToLiters(double dGal) { 
    double dTotGal = 0;     
    dTotGal = dGal * GAL_TO_LT; 
     return dTotGal; 
    } 



public static double calculateLitersToGallons(double dLit){ 

    double dTotLt = 0;    
    dTotLt = dLit * LT_TO_GAL; 
     return dTotLt; 
    } //end 


public static double calculateTeaspoonsToMliters(double dMlit){ 

    double dTotMl = 0;    
    dTotMl = dMlit * TSP_TO_ML; 
     return dTotMl; 
    } //end 


public static double calculateMlitersToTeaspoons(double dTsp){ 
    double dTotTsp = 0;    
    dTotTsp = dTsp * ML_TO_TSP; 
     return dTotTsp; 
    } //end 


public static void printResult(int nOpt, int nResultOperation){ 
     System.out.println("The total gallons is : " + nResultOperation); 

    }//end method printResult} //end class 

Answer 1

你需要調用轉換方法以及。 更改

public static void printResult(int nOpt, int nResultOperation){ 
    System.out.println("The total gallons is : " + nResultOperation); 
} 

到

public static void printResult(String unit, double result){ 
    System.out.println("The total " + unit + " is : " + result); 
} 

和

if (nConversion == 1) {   
    System.out.print("Please enter the gallons: "); 
    double dGal = input.nextDouble(); 
} 

到

if (nConversion == 1) {   
    System.out.print("Please enter the gallons: "); 
    double dGal = input.nextDouble(); 
    double litres = calculateGallonsToLiters(dGal); 
    printResult("litres", litres); 
} 

Answer 2

除了由Aidin給予我想建議使用switch語句，而不是正確的答案我的f/else並去掉所有不需要的，不重要的代碼，以使代碼可讀：

import java.util.Scanner; 
public class ConversionProgram { 

    public static final double LT_TO_GAL = .274; 
    public static final double GAL_TO_LT = 3.785;   
    public static final double TSP_TO_ML = 4.9289; 
    public static final double ML_TO_TSP = .202; 


    public static void main(String[] args) { 

     Scanner input = new Scanner(System.in); 

     System.out.println("CONVERSION TOOL: "); 
     System.out.println("1. Gallons to liters "); 
     System.out.println("2. Liters to gallons"); 
     System.out.println("3. Teaspoons to milliliters"); 
     System.out.println("4. Milliliters to teaspoons"); 
     System.out.print(""); 

     System.out.print("Please select the type of conversion you would like to make: "); 
     int nConversion = input.nextInt(); 

     switch (nConversion){ 
      case 1: 
       System.out.print("Please enter the gallons: "); 
       printResult("liters",calculateGallonsToLiters(input.nextDouble())); 
       break; 
      case 2: 
       System.out.print("Please enter the total liters: "); 
       printResult("gallons",calculateLitersToGallons(input.nextDouble())); 
       break; 
      case 3: 
       System.out.print("Please enter the total teaspoons "); 
       printResult("milliliters",calculateTeaspoonsToMliters(input.nextDouble())); 
       break; 
      case 4: 
       System.out.print("Please enter the total milliliters "); 
       printResult("teaspoons",calculateTeaspoonsToMliters(input.nextDouble())); 
       break; 
      default: 
       System.out.println("Not a valid option!");  
     } 
    } 

    public static double calculateGallonsToLiters(double dGal) { 
     return dGal * GAL_TO_LT; 
    } 

    public static double calculateLitersToGallons(double dLit){ 
     return dLit * LT_TO_GAL; 
    } 

    public static double calculateTeaspoonsToMliters(double dMlit){ 
     return dMlit * TSP_TO_ML; 
    } 

    public static double calculateMlitersToTeaspoons(double dTsp){ 
     return dTsp * ML_TO_TSP; 
    } 

    public static void printResult(String nOpt, double nResultOperation){ 
     System.out.println("The total " + nOpt + " is : " + nResultOperation); 
    } 
}