Grace JavaLog

Legacy System.out.print

Grace Software

JavaLog

$Revision: 1.2 $

$Date: 1999/10/28 11:17:24 $

Legacy System.out.print() Integration

If you are porting code that uses System.out.print() or System.err.print() statements, you can still use some of the features of JavaLog without changing the code. JavaLog can be installed as the System.out or err stream such that all uses of the the System.out or err will be routed through JavaLog and thus can be filtered.

Using the PrintCatcher allows you to use your existing code with print statements but still use indirection, formatting, and filtering of JavaLog. Currently, this functionality is experimental but will improve over time. Of course, it is better to use the actual JavaLog interfaces.

Here's how to use it: before making any calls to System.out or System.err, instantiate and install the special java.log.PrintCatcher:

    import grace.log.PrintCatcher;
    ...
    public static void main(String[] args) 
        PrintCatcher.install();
	...
	System.out.print("some starting text; now a number ");
	System.out.print(1);
	System.out.println(" some ending text.");

	System.err.println("some error text that now goes through JavaLog");

        PrintCatcher.uninstall(); // if you want to go back to old standard out and err
    }

Notice in the above example, the data printed using print(...) (as opposed to println) are buffered until a println call is made, and then the whole previously buffered line is written as a single log event. This should probably be the desired behavior for most users but it can be changed using the PrintCatcher.setBufferedPrints() function.

Also note that the PrintCatcher.install and PrintCatcher.uninstall() can be called repeatedly to alternate between using JavaLog or not using it for print statements.