Java: System. out. println and System. err. println are confused in the output

Question

Java: System. out. println and System. err. println are confused in the output

There is a task: use the commands System.out.println and System.err.println to print the text in a red frame. Like like this:

*******
*текст*
*******

But when output to IDEA, the text always crashes before the frame, then after, then otherwise, but not according to the task. In Eclipse, I saw that it works. I understand that there is a problem in the threads, but I can't solve it.

System.err.print("*******\n");
System.err.print("|");
System.out.print("text");
System.err.print("|");
System.err.print("*******\n");

1

java потоки-данных

Author: Qwertiy, 2017-12-13

Source

3 answers

score 1 · Answer 1

Try this (clear the buffer after each output):

print(System.err, "*******\n");
print(System.err,"|");
print(System.out,"text");
print(System.err,"|");
print(System.err,"*******\n");

private void print(PrintStream ps, String output)  {
    ps.print(output);
    ps.flush();
}

score 1 · Answer 2

The fact is that System.out.print buffers data for output, unlike System.err.print.

What does this mean ?

For example, you type using System.out.println. Then perform some operations, then print again. System.out.println prints all the elements at once, not one at a time.

System.err.print instantly prints items without buffering the data.

score 0 · Answer 3

We solved the problem like this:

public static void main(String[] args) {
    try {
        System.err.print("**********\n|  ");
        System.err.flush();
        Thread.sleep(50);
        System.out.print("text");
        System.out.flush();
        Thread.sleep(50);
        System.err.print("  |\n**********");
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
}