Java: variable used in run method, initialized in for loop is not recognized in for loop's statement

Question

/*
 * File: Countdown.java
 * ----------------------
 * This program counts backwards from the value  START
 * to zero, as in the countdown preceding a rocket launch.
 */

import acm.program.*;

public class Countdown extends ConsoleProgram  {

    public void run () {
        for (int t = START; t >= 0; t-- ); {
            println(t);
        }
        println ("Liftoff!");
    }
/* Specifies the value from which to start the countdown.*/

    private static final int START = 10;
}

My problem is that the (t) in the following statement is not recognized as a variable:

println(t);

Eran · Accepted Answer · 2015-12-13 09:27:41Z

4

Change

for (int t = START; t >= 0; t-- ); {
                                 ^
    println(t);
}

to

for (int t = START; t >= 0; t--) {
    println(t);
}

The ; closed the for statement, which means the following {} block was not part of the loop, so t wasn't defined in the scope of that block.

answered Dec 13, 2015 at 9:27

Eran

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1 Comment

Alexandra Cecilia Martinez Over a year ago

Thank you so much :) i'm obviously new :)

Community · Accepted Answer · 2017-05-23 12:23:12Z

0

(This is arguably a comment on Eran's answer, but has to be posted as an answer to get the necessary formatting.)

You should use a Java-aware editor, and reformat regularly using it, but especially when you do not understand an error. I reformatted the code from the question using Eclipse. Here is the result:

for (int t = START; t >= 0; t--)
  ;
{
  println(t);
}

The significance of the ";", and the fact that the block is at the same level as the for-loop are both hidden by the original formatting and put front-and-center by the reformatting.

edited May 23, 2017 at 12:23

CommunityBot

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answered Dec 13, 2015 at 9:52

Patricia Shanahan

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1 Comment

Alexandra Cecilia Martinez Over a year ago

I use Eclipse myself. Never used a reformatting option. I am new, just trying to follow a book's exercises.

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