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Panda Core is the core module of Panda Framework, it contains commonly used utility classes similar to apache-commons.
There is a newer version: 1.8.0
package panda.log;

import java.io.PrintStream;

/**
 * This class used to output log statements from within the log package.
 */
public class LogLog {
	/**
	 * Defining this value makes LOG print log internal debug statements to
	 * System.out.
	 * 
	 * The value of this string is panda.log.debug.
	 * 
	 * Note that the search for all option names is case sensitive.
	 */
	public static final String DEBUG_KEY = "panda.log.debug";

	/** output stream */
	public static PrintStream output;

	protected static boolean debugEnabled = false;

	/**
	 * In quietMode not even errors generate any output.
	 */
	private static boolean quietMode = false;

	private static final String PREFIX = "log: ";
	private static final String ERR_PREFIX = "log:ERROR ";
	private static final String WARN_PREFIX = "log:WARN ";

	static {
		String key = System.getProperty(DEBUG_KEY);
		if ("true".equalsIgnoreCase(key)) {
			debugEnabled = true;
		}
	}

	/**
	 * Allows to enable/disable LOG internal logging.
	 * @param enabled weather to enable internal debug
	 */
	public static void setInternalDebugging(boolean enabled) {
		debugEnabled = enabled;
	}

	private static PrintStream getOutput(boolean error) {
		if (output != null) {
			return output;
		}
		return error ? System.err : System.out;
	}
	
	/**
	 * This method is used to output LOG internal debug statements. Output goes to
	 * System.out.
	 * 
	 * @param msg the message
	 */
	public static void debug(String msg) {
		if (debugEnabled && !quietMode) {
			getOutput(false).println(PREFIX + msg);
		}
	}

	/**
	 * This method is used to output LOG internal debug statements. Output goes to
	 * System.out.
	 * 
	 * @param msg the message
	 * @param t the exception
	 */
	public static void debug(String msg, Throwable t) {
		if (debugEnabled && !quietMode) {
			getOutput(false).println(PREFIX + msg);
			if (t != null) {
				t.printStackTrace(getOutput(false));
			}
		}
	}

	/**
	 * This method is used to output LOG internal error statements. There is no way to disable
	 * error statements. Output goes to System.err.
	 * 
	 * @param msg the message
	 */
	public static void error(String msg) {
		if (quietMode) {
			return;
		}
		getOutput(true).println(ERR_PREFIX + msg);
	}

	/**
	 * This method is used to output LOG internal error statements. There is no way to disable
	 * error statements. Output goes to System.err.
	 * 
	 * @param msg the message
	 * @param t the exception
	 */
	public static void error(String msg, Throwable t) {
		if (quietMode) {
			return;
		}
		
		getOutput(true).println(ERR_PREFIX + msg);
		if (t != null) {
			t.printStackTrace(getOutput(true));
		}
	}

	/**
	 * In quite mode no LogLog generates strictly no output, not even for errors.
	 * 
	 * @param quietMode A true for not
	 */
	public static void setQuietMode(boolean quietMode) {
		LogLog.quietMode = quietMode;
	}

	/**
	 * This method is used to output log internal warning statements. There is no way to disable
	 * warning statements. Output goes to System.err.
	 * 
	 * @param msg the message
	 */
	public static void warn(String msg) {
		if (quietMode) {
			return;
		}
		
		getOutput(true).println(WARN_PREFIX + msg);
	}

	/**
	 * This method is used to output log internal warnings. There is no way to disable warning
	 * statements. Output goes to System.err.
	 * 
	 * @param msg the message
	 * @param t the exception
	 */
	public static void warn(String msg, Throwable t) {
		if (quietMode) {
			return;
		}

		getOutput(true).println(WARN_PREFIX + msg);
		if (t != null) {
			t.printStackTrace(getOutput(true));
		}
	}
}