printStackTrace to java.util.logging.Logger

Question

How do I print the entire stack trace using java.util.Logger? (without annoying Netbeans).

The question should've originally specified staying within Java SE. Omitting that requirment was an error on my part.

-do-compile:
    [mkdir] Created dir: /home/thufir/NetBeansProjects/rainmaker/build/empty
    [mkdir] Created dir: /home/thufir/NetBeansProjects/rainmaker/build/generated-sources/ap-source-output
    [javac] Compiling 13 source files to /home/thufir/NetBeansProjects/rainmaker/build/classes
    [javac] /home/thufir/NetBeansProjects/rainmaker/src/model/TelnetEventProcessor.java:44: error: 'void' type not allowed here
    [javac]                 log.severe(npe.printStackTrace(System.out));
    [javac]                                               ^
    [javac] 1 error

BUILD FAILED

code with the error:

package model;

import java.util.Observable;
import java.util.logging.Logger;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class TelnetEventProcessor extends Observable {

    private static Logger log = Logger.getLogger(TelnetEventProcessor.class.getName());
    private String string = null;

    public TelnetEventProcessor() {
    }

    private void stripAnsiColors() {
        Pattern regex = Pattern.compile("\\e\\[[0-9;]*m");
        Matcher regexMatcher = regex.matcher(string);
        string = regexMatcher.replaceAll(""); // *3 ??
    }

    public void parse(String string) {
        this.string = string;
        ifs();
    }

    //       [\w]+(?=\.) 
    private void ifs() {
        log.fine("checking..");
        if (string.contains("confusing the hell out of")) {
            Pattern pattern = Pattern.compile("[\\w]+(?=\\.)");  //(\w+)\.
            Matcher matcher = pattern.matcher(string);
            String enemy = null;
            GameData data = null;
            while (matcher.find()) {
                enemy = matcher.group();
            }
            try {
                data = new GameData.Builder().enemy(enemy).build();
                log.fine("new data object\t\t" + data.getEnemy());
                setChanged();
                notifyObservers(data);
            } catch (NullPointerException npe) {
                log.severe(npe.printStackTrace(System.out));
            }

        } else if (string.contains("Enter 3-letter city code:")) {
            log.fine("found enter city code");
        } else {
        }
    }
}

see also:

https://stackoverflow.com/a/7100975/262852

Answer 1

The severe method is only used to log severe messages without associated throwable information. If you need to log throwable information then you should use the log method instead:

try {
     data = new GameData.Builder().enemy(enemy).build();
     log.fine("new data object\t\t" + data.getEnemy());
     setChanged();
     notifyObservers(data);
} catch (NullPointerException npe) {
     log.log(Level.SEVERE, npe.getMessage(), npe);
}

Answer 2

Why don't you put the exception in the logger?

You can use this method :

logger.log(Level level, String msg, Throwable thrown) 

Answer 3

Maybe a duplicated question? Java - Need a logging package that will log the stacktrace

Below the explanation from the given url

Using log4j this is done with:

logger.error("An error occurred", exception);

The first argument is a message to be displayed, the second is the exception (throwable) whose stacktrace is logged.

Another option is commons-logging, where it's the same:

log.error("Message", exception);

With java.util.logging this can be done via:

logger.log(Level.SEVERE, "Message", exception);

Answer 4

You don't explicitly print the stack trace; Throwables have stack traces attached to them, and you can pass a Throwable to the log methods:

log(Level level, String msg, Throwable thrown)

Answer 5

You could use Apache ExceptionUtils. In your case

try {
     data = new GameData.Builder().enemy(enemy).build();
     log.fine("new data object\t\t" + data.getEnemy());
     setChanged();
     notifyObservers(data);
 } catch (NullPointerException npe) {
     logger.info(**ExceptionUtils.getFullStackTrace(npe)**);
 }

Answer 6

You should redirect the System.err to the logger, the process is not too simple but you can use this code:

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;

public class LogOutputStream extends ByteArrayOutputStream {//java.io.OutputStream {

    private String  lineSeparator;
    private Logger  logger;
    private Level   level;

    public LogOutputStream(Logger logger, Level level) {
        super();
        this.logger = logger;
        this.level = level;
        this.lineSeparator = System.getProperty("line.separator");
    }

    @Override
    public void flush() throws IOException {

        String record;
        synchronized (this) {
            super.flush();
            record = this.toString();
            super.reset();

            if ((record.length() == 0) || record.equals(this.lineSeparator)) {
                // avoid empty records 
                return;
            }

            this.logger.logp(this.level, "", "", record);
        }
    }
}

And The code to set this (that should called the when you first create the logger

Logger logger = Logger.getLogger("Exception");
LogOutputStream los = new LogOutputStream(logger, Level.SEVERE);
System.setErr(new PrintStream(los, true));

This will redirect the System.err stream to the logger.

Answer 7

You can also try to use ExceptionUtils from apache commons

Answer 8

The exception is due to the printstacktrace method being void, meaning it doesn't return anything. You are trying to do:

log.severe(npe.printStackTrace(System.out));

My guess is that the severe method needs a String and not void.