Passing parameters in Java Program

Parameter Passing Program in Java

/**

* This program demonstrates parameter passing in Java.

*/

public class ParamTest

{

public static void main(String[] args)

{

/*

* Test 1: Methods can't modify numeric parameters

*/

System.out.println("Testing tripleValue:");

double percent = 10;

System.out.println("Before: percent=" + percent);

tripleValue(percent);

System.out.println("After: percent=" + percent);

/*

* Test 2: Methods can change the state of object parameters

*/

System.out.println("\nTesting tripleSalary:");

Employee harry = new Employee("Harry", 50000);

System.out.println("Before: salary=" + harry.getSalary());

tripleSalary(harry);

System.out.println("After: salary=" + harry.getSalary());

/*

* Test 3: Methods can't attach new objects to object parameters

*/

System.out.println("\nTesting swap:");

Employee a = new Employee("Alice", 70000);

Employee b = new Employee("Bob", 60000);

System.out.println("Before: a=" + a.getName());

System.out.println("Before: b=" + b.getName());

swap(a, b);

System.out.println("After: a=" + a.getName());

System.out.println("After: b=" + b.getName());

}

public static void tripleValue(double x) // doesn't work

{

x = 3 * x;

System.out.println("End of method: x=" + x);

}

public static void tripleSalary(Employee x) // works

{

x.raiseSalary(200);

System.out.println("End of method: salary=" + x.getSalary());

}

public static void swap(Employee x, Employee y)

{

Employee temp = x;

x = y;

y = temp;

System.out.println("End of method: x=" + x.getName());

System.out.println("End of method: y=" + y.getName());

}

}

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;

}

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