Possible Duplicate: Java: System.out.println and System.err.println out of order Why this code System.err.println(err); System.out.println(out);

Question

Editorial Team

Asked: June 15, 20262026-06-15T04:29:16+00:00 2026-06-15T04:29:16+00:00

Possible Duplicate:
Java: System.out.println and System.err.println out of order

Why this code

    System.err.println("err");
    System.out.println("out");

prints

out
err

on Eclipse console?

UPDATE

The same code prints in correct order if I run it from command line.

UPDATE

If I fix it as

    System.err.println("err");
    Thread.sleep(5);
    System.out.println("out");

It prints correctly in Eclipse too

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Editorial Team · Answer 1 · 2026-06-15T04:29:17+00:00

Editorial Team

It’s not slower; they’re just not necessarily flushed in order. You can fix that, however:

System.err.println("err");
System.err.flush();
System.out.println("out");

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