I'm writing a program in Java that simulates gravity, and in it I have a bunch of log statements (to System.out). My program is running really slowly, and I think the logging might be part of the reason. Is there any way to disable System.out, so that my program doesn't slow down when printing, or do I have to manually go through and comment/uncomment each one to enable/disable debug statements?
I agree with others that a proper logger should be used. However that is not possible in every case. The following code disables out and is fast as OP asked:
System.setOut(new java.io.PrintStream(new java.io.OutputStream() {
@Override public void write(int b) {}
}) {
@Override public void flush() {}
@Override public void close() {}
@Override public void write(int b) {}
@Override public void write(byte[] b) {}
@Override public void write(byte[] buf, int off, int len) {}
@Override public void print(boolean b) {}
@Override public void print(char c) {}
@Override public void print(int i) {}
@Override public void print(long l) {}
@Override public void print(float f) {}
@Override public void print(double d) {}
@Override public void print(char[] s) {}
@Override public void print(String s) {}
@Override public void print(Object obj) {}
@Override public void println() {}
@Override public void println(boolean x) {}
@Override public void println(char x) {}
@Override public void println(int x) {}
@Override public void println(long x) {}
@Override public void println(float x) {}
@Override public void println(double x) {}
@Override public void println(char[] x) {}
@Override public void println(String x) {}
@Override public void println(Object x) {}
@Override public java.io.PrintStream printf(String format, Object... args) { return this; }
@Override public java.io.PrintStream printf(java.util.Locale l, String format, Object... args) { return this; }
@Override public java.io.PrintStream format(String format, Object... args) { return this; }
@Override public java.io.PrintStream format(java.util.Locale l, String format, Object... args) { return this; }
@Override public java.io.PrintStream append(CharSequence csq) { return this; }
@Override public java.io.PrintStream append(CharSequence csq, int start, int end) { return this; }
@Override public java.io.PrintStream append(char c) { return this; }
});
My sample measurements were:
write(int)
in OutputStream
PrintStream
methods as wellprintln
and printf
usagesSo it is faster than other answers here, but can't beat non-existent code (commenting out System.out
s or wrapping in if (DEBUG)
) as varargs allocates arrays and boxes primitives or StringBuilder
(+
too) still executes.