D.4. Declaring Methods with Multiple Parameters

We now consider how to write your own methods with multiple parameters. Figure D.2 uses a method called maximum to determine and return the largest of three double values. In main, lines 14–18 prompt the user to enter three double values, then read them from the user. Line 21 calls method maximum (declared in lines 28–41) to determine the largest of the three values it receives as arguments. When method maximum returns the result to line 21, the program assigns maximum’s return value to local variable result. Then line 24 outputs the maximum value. At the end of this section, we’ll discuss the use of operator + in line 24.

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 1   // Fig. D.2: MaximumFinder.java
 2   // Programmer-declared method maximum with three double parameters.
 3   import java.util.Scanner;
 4
 5   public class MaximumFinder
 6   {
 7      // obtain three floating-point values and locate the maximum value
 8      public static void main( String[] args )
 9      {
10         // create Scanner for input from command window
11         Scanner input = new Scanner( System.in );
12
13         // prompt for and input three floating-point values
14         System.out.print(
15            "Enter three floating-point values separated by spaces: " );
16         double number1 = input.nextDouble(); // read first double
17         double number2 = input.nextDouble(); // read second double
18         double number3 = input.nextDouble(); // read third double
19
20         // determine the maximum value
21         double result = maximum( number1, number2, number3 );
22
23         // display maximum value
24         System.out.println( "Maximum is: " + result );
25      } // end main
26
27      // returns the maximum of its three double parameters          
28      public static double maximum( double x, double y, double z )   
29      {                                                              
30         double maximumValue = x; // assume x is the largest to start
31                                                                     
32         // determine whether y is greater than maximumValue         
33         if ( y > maximumValue )                                     
34            maximumValue = y;                                        
35                                                                     
36         // determine whether z is greater than maximumValue         
37         if ( z > maximumValue )                                     
38            maximumValue = z;                                        
39                                                                     
40            return maximumValue;                                     
41      } // end method maximum                                        
42   } // end class MaximumFinder

Fig. D.2 | Programmer-declared method maximum with three double parameters.