import java.util.Date;public class ParamTest
{
public static void tripleValue(double value)
{
value = 3 * value; System.out.println("End of method: value=" + value);
} public static void swap(Employee a, Employee b) { Employee temp = a; a = b; b= temp; System.out.println("End of method: a=" + a.getName()); System.out.println("End of method: b=" + b.getName()); } public static void tripleSalary(Employee e) { e.raiseSalary(200); System.out.println("End of method: salary=" + e.getSalary()); } public static void main(String[] args) { /* * Test 1: Method 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, new Date()); 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, new Date()); Employee b = new Employee("Bob", 60000, new Date()); 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()); }
}紼嬪簭鎵撳嵃緇撴灉涓猴細
Testing tripleValue:
Before: percent=10.0
End of method: value=30.0
After: percent=10.0
Testing tripleSalary
Before: salary=50000.0
End of method: salary=150000.0
After: salary=150000.0
Testing swap
Before: a=Alice
Before: b=Bob
End of method: a=Bob
End of method: b=Alice
After: a=Alice
After: b=Bob
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