class Circle{
double dbRadius;
Circle(double radius) {
dbRadius=radius;
}
public double Area() {
return 3.14*dbRadius*dbRadius;
}}public class Test2 {
public static void main(String[] args)
{
Circle circle1=new Circle(5.0);
Circle circle2=new Circle(3.0);
swap(circle1,circle2);
System.out.println(circle1.Area());
System.out.println(circle2.Area());
}
public static void swap(Circle cir1,Circle cir2) {
Circle circle;
circle=cir1;
cir1=cir2;
cir2=circle;
}
此程序的运行结果为:
78.5
28.259999999999998
swap()函数显然没有交换掉对象变量
circle1,circle2
原因可能就是参数按值传递的,
java中怎样能像C/C++一样
按 swap(&circle, &circle2)
把对象变量的地址传过去,使结果为
28.259999999999998
78.5
double dbRadius;
Circle(double radius) {
dbRadius=radius;
}
public double Area() {
return 3.14*dbRadius*dbRadius;
}}public class Test2 {
public static void main(String[] args)
{
Circle circle1=new Circle(5.0);
Circle circle2=new Circle(3.0);
swap(circle1,circle2);
System.out.println(circle1.Area());
System.out.println(circle2.Area());
}
public static void swap(Circle cir1,Circle cir2) {
Circle circle;
circle=cir1;
cir1=cir2;
cir2=circle;
}
此程序的运行结果为:
78.5
28.259999999999998
swap()函数显然没有交换掉对象变量
circle1,circle2
原因可能就是参数按值传递的,
java中怎样能像C/C++一样
按 swap(&circle, &circle2)
把对象变量的地址传过去,使结果为
28.259999999999998
78.5
JAVA传递的是引用
你这样的结果是最后
cir1==cir2
两个对象变成一样的了要用clone来交换
class Circle{
double dbRadius;
Circle(double radius) {
dbRadius=radius;
}
public double Area() {
return 3.14*dbRadius*dbRadius;
}
}public class Test2 {
public static void main(String[] args){
Circle circle1=new Circle(5.0);
Circle circle2=new Circle(3.0);
Circle circle[] = swap(circle1,circle2);
circle1 = circle[0];
circle2 = circle[1];
System.out.println(circle1.Area());
System.out.println(circle2.Area());
}
public static Circle[] swap(Circle cir1,Circle cir2) {
Circle circle;
circle=cir1;
cir1=cir2;
cir2=circle;
return new Circle[]{cir1, cir2};
}
}
cir1 不等于 cir2 ,引用其实也是地址,也不知道该怎么说,你的例子是这样的
假如 circle1 = "AAAAA" ,circle2 = "BBBBB" ,你传值过去,cir1 ="AAAAA" cir2 = "BBBBB",而你在swap()里只是对cir1 和cir2,进行交换,确实也交换了,但是对circle1 和circle2 没有影响。老师常说,你把引用看成拴牛的绳子,你对引用操作,就是对栓的牛的绳子的操作,而不是对牛进行操作。
{
private:
int age;
string name;
public:
int getage();
string getname;
C1(int &age = 10,string &name = "Tom");
};C1::C1(int age,string name)
{
this->age = age;
this->name = name;
}int C1::getage()
{
return this->age;
}string C1::getname()
{
return this->name;
}
int main()
{
C1 c1(5,"Jerry);
C1 *pC1 = &c1;/////这里获取c1对象的地址
pC1 = new C1(10000,"ghost"); delete pC1;
}言外之意:java是不能获取对象地址的