Class Debug

java.lang.Object

Debug

public class Debug
extends java.lang.Object

In writing your code, you may be tempted to use System.out.printf() to determine what is happening. As an alternative, the method printf(String, Object...) is provided. The nice thing about printf(String, Object...) in comparison to System.out.printf() is that Debug.printf() only prints when debug is turn on.

You can turn debug on and off by setting the debugLevel variable to non zero. This is normally done by a command line parameter to the main() of your program. This module allows you to write debug code, but not need to change your program in any way before turning it in.

If you use System.out.printf() you MUST either comment out the lines or remove them before you submit your code for grading. This is a simple alternative to the many logging packages that have more advanced capabilities. See this page for examples.

Field Summary

Fields

Modifier and Type	Field and Description
static int	debugLevel Controls how much debug output is produced.

Method Summary

Modifier and Type	Method and Description
static void	close() Close the output stream if it is not System.err.
static java.lang.String	format(java.lang.String format, java.lang.Object... args) An "extension" of String.format(String, Object...).
static boolean	HERE() Simple routine to print the fileName, lineNumber and methodName.
static java.lang.String[]	init(java.lang.String[] args) This routine will set the debugLevel from the arguments passed to main().
static boolean	printf(int level, java.lang.String format, java.lang.Object... args) Print a message if the parameter level is less than or equal to debugLevel.
static boolean	printf(java.lang.String format, java.lang.Object... args) Print a message if the variable debugLevel is non-zero.
static void	toFile(java.lang.String fileName) Send debugging output to a file.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

debugLevel

public static int debugLevel

Controls how much debug output is produced.

A value of 0 means no output. This is normally set by your program's main() or by a command line argument. With the debugLevel you can vary the amount of output from none, to a lot.

Method Detail

init

public static java.lang.String[] init(java.lang.String[] args)

This routine will set the debugLevel from the arguments passed to main(). If the first argument is -d or -dDigit. the value will be used to initialize debugLevel and that argument will be removed.

Parameters:

args - the array of arguments passed to main

Returns:

the args with the first value removed (if appropriate)

format

public static java.lang.String format(java.lang.String format,
                                      java.lang.Object... args)

An "extension" of String.format(String, Object...). Automatically converts arrays to Strings using the Arrays.toString() methods. Arrays of arrays are also handled. The argument list is exactly the same as that of String.format(), so any of the features of that code may be used. If there is only a single argument after the format and if that argument is an array, cast it to an Object using (Object)

Parameters:

format - the format string for the output (use %s for arrays)

args - arguments for the format string (variable number)

Returns:

the formatted string with all array objects expanded

HERE

public static boolean HERE()

Simple routine to print the fileName, lineNumber and methodName. Used for quick debugging to see if your code even gets to a particular place.

Returns:

always returns true. Allows you to "abuse" the assert statement for high performance.

printf

public static boolean printf(java.lang.String format,
                             java.lang.Object... args)

Print a message if the variable debugLevel is non-zero.

The argument list is exactly the same as that of String.format(String, Object...), so any of the features of that code may be used. See the documentation of format(String, Object...) for details on printing arrays.

Parameters:

format - the format string for the output

args - arguments for the format string (variable number)

Returns:

always returns true. Allows you to "abuse" the assert statement for high performance.

printf

public static boolean printf(int level,
                             java.lang.String format,
                             java.lang.Object... args)

Print a message if the parameter level is less than or equal to debugLevel.

The argument list following level is exactly the same as that of String.format(String, Object...), so any of the features of that code may be used. See the documentation of format(String, Object...) for details on printing arrays.

Parameters:

level - controls whether message is printed or not

format - the format string for the output

args - arguments for the format string (variable number)

Returns:

always returns true. Allows you to "abuse" the assert statement for high performance.

toFile

public static void toFile(java.lang.String fileName)
                   throws java.io.FileNotFoundException

Send debugging output to a file.

Parameters:

fileName - name of the file to send output to

Throws:

java.io.FileNotFoundException - if unable to access the file

close

public static void close()

Close the output stream if it is not System.err. For use in conjunction with toFile(String)