Regarding contiue keyword

[Reguri Praveen]

Please help to understand the logic behind this program
class XY
{
static int x;
public static void main(String args[])
{
outer:
for (int i=0;i<5;i++)
{
if ( x==0 )
{
x++;
continue outer;
}
System.out.print(i);
}
}
}

The output of the above program is :1234

My query is that the int variable i in for loop is a local variable and should be reset to 0 when control goes out of the loop. Once the control is at the label outer, the value of the int i should be lost and i should be set to 0. But the value is retained by i.


Similarly with a few modifications where continue is replaced with break the below code generating the error while accessing the value of i outside the for loop

class XY
{
static int x;
public static void main(String args[])
{
loop:
for (int i=0;i<5;i++)
{
if ( x==0)
{
x++;
break loop;
}
System.out.println(i);
}
System.out.println(i);
}
}


Error is
XY.java:16: cannot resolve symbol
symbol : variable i
location: class XY
System.out.println(i);
^
1 error

[Henry Wong]

My query is that the int variable i in for loop is a local variable and should be reset to 0 when control goes out of the loop. Once the control is at the label outer, the value of the int i should be lost and i should be set to 0. But the value is retained by i.

The label is used to determine which loop you are refering to -- in order to do the "continue" operation. A "continue" does not leave the loop. It does not restart the loop. It ends the current iteration, and starts the next one.

Henry

[Henry Wong]

Similarly with a few modifications where continue is replaced with break the below code generating the error while accessing the value of i outside the for loop

You did more than replace "continue" with "break" -- you added a new println statement. A println statement that uses "i" when it is out of scope -- which is why the compiler is complaining.

Henry

[Edisandro Bessa]

Just in addition to Henry's reply, if your label is refering to another loop outer than loop you are calling the continue statement, in this case, the inner loop local variable will be initialized.

class ContinueTest
{
    static int x;
    
    public static void main(String args[])
    {
        outer:
        for (int z=0;z<3;z++)
            for (int i=0;i<3;i++)
            {
                if ( x==0 )
                {
                    x++;
                    continue outer;
                }
                System.out.println(" z :" + z + " i:" + i);
            }
    }
}

Output is :
z :1 i:0
z :1 i:1
z :1 i:2
z :2 i:0
z :2 i:1
z :2 i:2

[Changchun Wang]

Error is
XY.java:16: cannot resolve symbol
symbol : variable i
location: class XY
System.out.println(i);
^
1 error

if you want why the complie time error occurs ,I will talk wiith you the reason
your program is just like that (attentin:I don't talk you with the label continue or break,I say something about the scoping of the variable )

 {
         [B]{[/B]int i=3;
 
        [B] } [/B]
       System.out.println(""+i);// a complie time error
       } 
       

now you can see the local variable is in the inner bracket,so in the outer bracket except in the inner bracket this variable is NOT visible