Réduire la duplication de code lors de la lecture de différents types de numéros depuis la console

Question

J'ai créé trois méthodes readLong, readInt et readDouble qui font essentiellement la même chose. La seule différence est la méthode appelée par un scanner. Comment puis-je réduire le code en double en les transformant tous en une seule méthode?

public long readLong(String description) 
    { 
     System.out.println(description); 
     long nrToReturn = 0; 
     boolean acceptedValue = false; 

     do { 
      System.out.println(); 
      System.out.print("Choose one: "); 
      try 
      { 
       nrToReturn = consoleScanner.nextLong(); //Only line thats different except return value 
       acceptedValue = true; 
      }catch(Exception e) 
      { 
       acceptedValue = false; 
       consoleScanner.nextLine(); 
      } 
     }while (!acceptedValue); 

     consoleScanner.nextLine(); 
     return nrToReturn; 
    } 

Answer 1

Ici nous allons avec une idée:

import java.util.Scanner; 

public class ScannerTest { 

    private Scanner consoleScanner; 

    public ScannerTest() { 
     consoleScanner = new Scanner(System.in); 
    } 

    @SuppressWarnings("unchecked")  
    private <T extends Number> T readType(String description, Class<T> desiredType) { 
     System.out.println(description); 
     Number result = null; 

     while (result == null) { 
      System.out.println(); 
      System.out.print("Choose one: "); 
      try { 
       if (Integer.class.equals(desiredType)) { 
        result = new Integer(consoleScanner.nextInt()); 
       } else if (Long.class.equals(desiredType)) { 
        result = new Long(consoleScanner.nextLong()); 
       } 
      } catch(Exception e) { 
       consoleScanner.nextLine(); 
      } 
     } 

     consoleScanner.nextLine(); 
     return (T) result; 
    } 

    public long readLong(String description) { 
     return this.readType(description, Long.class); 
    } 

    public int readInt(String description) { 
     return this.readType(description, Integer.class); 
    } 

    public static void main(String[] args) { 
     ScannerTest t = new ScannerTest(); 
     t.readLong("Reading a long value..."); 
     t.readInt("Reading an integer value..."); 
    } 
} 

Mise à jour, suivant @ Michu93 idée d'une méthode transparente:

import java.util.Scanner; 

public class ScannerTest { 

    private Scanner consoleScanner; 

    public ScannerTest() { 
     consoleScanner = new Scanner(System.in); 
    } 

    @SuppressWarnings("unchecked") 
    public <T extends Number> T readNumber(String description) { 
     System.out.println(description); 
     Number result = null; 

     while (result == null) { 
      System.out.print("\nChoose one: "); 
      String textRead = consoleScanner.next(); 

      try { 
       result = new Integer(textRead); 
      } catch(Exception e1) { 
       try { 
        result = new Long(textRead); 
       } catch (Exception e2) { 
        try { 
         result = new Double(textRead); 
        } catch (Exception e3) { 
        } 
       } 
      } 
      consoleScanner.nextLine(); 
     } 

     return (T) result; 
    } 

    public static void main(String[] args) { 
     ScannerTest t = new ScannerTest(); 
     for (int i = 0; i < 3; i++) { 
      Number input = t.readNumber(i + ": Reading int, long or double..."); 
      System.out.println("Input class: " + input.getClass().getCanonicalName()); 
      System.out.println("Input value: " + input); 
     } 
    } 
}