问在Java中添加构造函数示例:入门指南，第7版

EN

 // Add a constructor.  

class Vehicle {   
  int passengers; // number of passengers   
  int fuelcap;    // fuel capacity in gallons  
  int mpg;        // fuel consumption in miles per gallon  

  // This is a constructor for Vehicle. 
  Vehicle(int p, int f, int m) { 
    passengers = p; 
    fuelcap = f; 
    mpg = m; 
  } 

  // Return the range.  
  int range() {  
    return mpg * fuelcap;  
  }  

  // Compute fuel needed for a given distance. 
  double fuelneeded(int miles) {  
    return (double) miles / mpg;  
  }  
}   

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

    // construct complete vehicles 
    Vehicle minivan = new Vehicle(7, 16, 21);   
    Vehicle sportscar = new Vehicle(2, 14, 12);   
    double gallons;  
    int dist = 252;  

    gallons = minivan.fuelneeded(dist);   

    System.out.println("To go " + dist + " miles minivan needs " +  
                       gallons + " gallons of fuel.");  

    gallons = sportscar.fuelneeded(dist);   

    System.out.println("To go " + dist + " miles sportscar needs " +  
                       gallons + " gallons of fuel.");  

  }   

}