CODEWITHSUNDEEP
java
jim layhey
jim layhey

Reputation: 91

Java printf complication

For this code to run as intended use your cmd/terminal not an IDE. (or you will not see the correct effect of \r)

When the 9 in the terminal reaches the right most position after 4 spaces it will turn around and move back 4 spaces and on and on. However when it reaches the start point after a full cycle there is a remaining 9 on the second space that is not cleared by \r. What could be causing this?

public class Core {
    public static void main(String[] args) throws InterruptedException {

        int Array[][] = new int[4][6];
        int score;
        boolean enemy = true;
        boolean dir = true;

        // EnemyLine
        while (enemy) {
            for (int i = 1;;) {
                Thread.sleep(1000);

                if (i == 1)
                    dir = true;
                else if (i == 4)
                    dir = false;
                if (dir == true) {
                    int a = Array[0][i] = 9;
                    System.out.printf("%" + i + "d", a);
                    i++;
                    System.out.print("\r");
                    continue;
                } else if (dir == false) {
                    int a = Array[0][i] = 9;
                    System.out.printf("%" + i + "d", a);
                    i--;
                    System.out.print("               \r");
                    continue;
                }
            }
        }

    }
}

Upvotes: 3

Views: 141

Answers (1)

Acewin
Acewin

Reputation: 1727

Explaining why you are getting such result

Basically in your loop you are changing where to place carriage return \r.

After loop completion when you come back to i = 1. your are changing after how many characters you are going to do a carriage return.

1 -> _9\r
2 -> __9\r
3 -> ___9\r
4 -> ____9      \r
x3 -> ___9       \r
x2 -> __9        \r
x1 -> _9\r

thus the last statement does not clear the 9 at x2

Change needed in if (dir == true) 

System.out.print(" \r" ); // enter a space before \r

or it would be best to use 

System.out.print("               \r" ); // preferable

you can also remove your sysout \r from the condition loop and use it before your Thread sleep

System.out.print("       \r" );
Thread.sleep(1000);

Upvotes: 3

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