javz notes: the use of interesting static methods

import .*;

public class welcome {

    public static void main(String[] args)
       {
          /*
           * Test 1: Methods can't modify numeric parameters
           */
          ("Testing tripleValue:");
          double percent = 10;
          ("Before: percent =" + percent);
          percent = tripleValue(percent);
("After: percent =" + percent);  //The output here is 30! Normal results

          /*
           * Test 2: Methods can change the state of object parameters
           */
          ("\nTesting tripleSalary:");
          Employee harry = new Employee("Harry", 50000);
          ("Before: salary =" + ());
          tripleSalary(harry);
          ("After: salary =" + ());

          /*
           * Test 3: Methods can't attach new objects to object parameters
           */
          ("\nTesting swap:");
          Employee a = new Employee("Alice", 70000);
          Employee b = new Employee("Bob", 60000);
          ("Before: a  =" + ());
          ("Before: b  =" + ());
          swap(a, b);
          ("After: a=" + ());
          ("After: b=" + ());
       }

       public static double tripleValue(double x) // doesn't work
       {
          return x = 3 * x;
          //("End of method: x=" + x);
       }

       public static void tripleSalary(Employee x) // works
       {
          (200);
          ("End of method: salary=" + ());
       }

       public static void swap(Employee x, Employee y)
       {
          Employee temp = x;
          x = y;
          y = temp;
          ("End of method: x=" + ());
          ("End of method: y=" + ());
       }
    }

    class Employee // simplified Employee class
    {
       public Employee(String n, double s)
       {
          name = n;
          salary = s;
       }

       public String getName()
       {
          return name;
       }

       public double getSalary()
       {
          return salary;
       }

       public void raiseSalary(double byPercent)
       {
          double raise = salary * byPercent / 100;
          salary += raise;
       }

       private String name;
       private double salary;
    }

/**
 * This program demonstrates parameter passing in Java.
 * @version 1.00 2000-01-27
 * @author Cay Horstmann
 */
public class ParamTest
{
   public static void main(String[] args)
   {
      /*
       * Test 1: Methods can't modify numeric parameters
       */
      ("Testing tripleValue:");
      double percent = 10;
      ("Before: percent=" + percent);
      tripleValue(percent);
      ("After: percent=" + percent);

      /*
       * Test 2: Methods can change the state of object parameters
       */
      ("\nTesting tripleSalary:");
      Employee harry = new Employee("Harry", 50000);
      ("Before: salary=" + ());
      tripleSalary(harry);
      ("After: salary=" + ());

      /*
       * Test 3: Methods can't attach new objects to object parameters
       */
      ("\nTesting swap:");
      Employee a = new Employee("Alice", 70000);
      Employee b = new Employee("Bob", 60000);
      ("Before: a=" + ());
      ("Before: b=" + ());
      swap(a, b);
      ("After: a=" + ());
      ("After: b=" + ());
   }

   public static void tripleValue(double x) // doesn't work
   {
      x = 3 * x;
      ("End of method: x=" + x);
   }

   public static void tripleSalary(Employee x) // works
   {
      (200);
      ("End of method: salary=" + ());
   }

   public static void swap(Employee x, Employee y)
   {
      Employee temp = x;
      x = y;
      y = temp;
      ("End of method: x=" + ());
      ("End of method: y=" + ());
   }
}

class Employee // simplified Employee class
{
   public Employee(String n, double s)
   {
      name = n;
      salary = s;
   }

   public String getName()
   {
      return name;
   }

   public double getSalary()
   {
      return salary;
   }

   public void raiseSalary(double byPercent)
   {
      double raise = salary * byPercent / 100;
      salary += raise;
   }

   private String name;
   private double salary;
}