| Java 5 |
You may not be allowed to convert any primitives
to reference types directly with assignment
operator using jdk version below 1.5.
int i = 123;
Object box = i; //OK for jdk 1.5
Integer ii = new Integer(i);
Object box = ii;
Integer ii = new Integer(123);
Object box = ii;
int i = ((Integer)box).intValue();
System.out.println(i);//123
class Point
{
public int x, y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
}
Point p = new Point(10, 10);
Object box = p;
p.x = 20;
System.out.print(((Point)box).x);//20
//Point is a reference type
int i = 5;
Stack stack = new Stack ();
stack.push (new Integer(i)); //wrapper
int j = (stack.pop()).intValue();
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| C# |
You may convert any value type to a corresponding
reference type, and to convert the resultant 'boxed'
type back again.
int i = 123;
object box = i;
if (box is int) {
System.Console.Write("Box contains an int");
}
unboxing
object box = 123;
int i = (int)box;
System.Console.Write(i);//123
struct Point
{
public int x, y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
}
Point p = new Point(10, 10);
object box = p;
p.x = 20;
System.Console.Write(((Point)box).x);//10
//Point is a value type
int i = 5;
Stack stack = new Stack ();
stack.Push (i); // box the int
int j = (int) stack.Pop(); // unbox the int
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