I need something similar to String.format(...) method, but with lazy evaluation.
This lazyFormat method should return some object whose toString() method would then evaluate the format pattern.
I suspect that somebody has already done this. Is this available in any libararies?
I want to replace this (logger is log4j instance):
if(logger.isDebugEnabled() ) {
logger.debug(String.format("some texts %s with patterns %s", object1, object2));
}
with this:
logger.debug(lazyFormat("some texts %s with patterns %s", object1, object2));
I need lazyFormat to format string only if debug logging is enabled.
if you are looking for a "simple" solution:
public class LazyFormat {
public static void main(String[] args) {
Object o = lazyFormat("some texts %s with patterns %s", "looong string", "another loooong string");
System.out.println(o);
}
private static Object lazyFormat(final String s, final Object... o) {
return new Object() {
@Override
public String toString() {
return String.format(s,o);
}
};
}
}
outputs:
some texts looong string with patterns another loooong string
you can of course add any isDebugEnabled()
statement inside lazyFormat if you will.