访问for循环之外的整数

Question

for (int x = 1; x <= 3; x++) {
  System.out.println("Number: " + x);
}
System.out.println("Done! Counted to: " + x);

This gives an error, suggesting to me that I can't access the variable outside the for loop.
Is there a way to do so?

Answer 1

Declare it outside of the for statement, then omit the first part of the for statement.

int x = 1;
for (; x <= 3; x++) {
    System.out.println("Number: " + x);
}

System.out.println("Done! Counted to: " + x);

Hint : You can omit any of the three parts of the for loop. For example, you might wish to omit the last part if you wish to do some conditional incrementing inside of the compound statement that makes up your for loop.

int x = 1;
for (; x <= 3;) {
    if (x % 2 == 0) {
        x += 2;
    } else {
        x++;
    }
}

Becareful with this kind of thing though. It's easy to find yourself in an infinite loop if you aren't careful.

Answer 2

Put x outside loop and use other variable for loop.

Code

int x = 0;
for (int i = 1; i <= 3; i++) {
    System.out.println("Number: " + i);
    x = i;
}
System.out.println("Done! Counted to: " + x);

Result

Number: 1
Number: 2
Number: 3
Done! Counted to: 3

Answer 3

Yes, very easily. Just do it like this:

int x = 0;
for (x=1; x<=3; x++) {
    System.out.println("Number: " +x);
}

System.out.println("Done! Counted to: "+x);

You don't have to declare a new variable in the loop, you can use an existing one if you want to.

Answer 4

When you declare a variable inside for loop, the scope of that variable is only within a loop.

In order to access that variable outside for loop, declare it outside.

int x =0;
for (x=1; x<=3; x++) {
    System.out.println("Number: " +x);
    }
    System.out.println("Done! Counted to: "+x);
    }
}

Answer 5

If the first part is useless, might as well use a while loop then.

int x = 1;

while (x <= 3)  
{         
    System.out.println("Number: " + x);        
    x++;   
}  

System.out.println("Done! Counted to: "+ x);

Answer 6

 
int x=1;
for (; x<=3; x++) {
  System.out.println("Number: " +x);
}
System.out.println("Done! Counted to: "+x);