java 传值问题

public class Cat {
private String id;
private String name;
public String getId() {
	return id;
}
public void setId(String id) {
	this.id = id;
}
public String getName() {
	return name;
}
public void setName(String name) {
	this.name = name;
}
public Cat(String id, String name) {
	this.id = id;
	this.name = name;
}

private static void changeName(Cat cat){
	cat.setName("other");
}

public static void main(String[] args) {
	Cat cat = new Cat ("1","kitty");
	changeName(cat); 
	System.out.println(cat.getName());
}
/*
 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());
    }

    private 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());
    }

    private static void tripleSalary(Employee x) {
        x.raiseSalary(200);
        System.out.println("End of method: salary=" + x.getSalary());
    }

    private static void tripleValue(double x) {
        x=3*x;
        System.out.println("End of Method X= "+x);
    }
}


Testing tripleValue:
Before: percent=10.0
End of Method X= 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: x=Bob  //可见引用的副本进行了交换
End of method: y=Alice
After: a=Alice  //引用本身没有交换
After: b=Bob

 */

}

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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