Aha, I fixed it by changing

    log4j.appender.stdout.Threshold=WARN

to 

    log4j.appender.stdout.Threshold=INFO


Should have been more careful first time round.

I have to do something very simple, but there doesn&#39;t seem to be an easy way to do this, as far as I can tell. I just want to load JSON data from a remote source and store it in a global Javascript variable using jQuery. Here&#39;s what I have:

    var my_json;
    $.getJSON(my_url, function(json) {
      var my_json = json;
    });

The my_json variable remains undefined. I think this is clearly a scope issue. It seems to me the $.getJSON method should return JSON, but it returns an XMLHttpRequest object. If I do this:

    request = $.getJSON(my_url);
    my_json = request.responseText.evalJSON();

That doesn&#39;t work because until the readystate == 4, the responsetext remains null. It seems you have to use the callback function to return the responsetext, since it fires on success.

It can&#39;t be this hard! Right?
 




load json into variable

At the moment I have to go to `/usr/java/apache-solr-1.4.0/example` and then do:

    java -jar start.jar

How do I get this to start automatically on boot? 

I&#39;m on a shared Linux server.


How to start Solr automatically?

Is it possible to configure different log levels for a single Logger based on the appender?

I realize this is similar to this [question][1], and this is as far as I had already got myself, but the problem with this is that the threshold applies to all loggers that log to that appender, whereas I only want the threshold to apply to a single logger.

i.e. So far I have something like this:


    log4j.rootLogger=WARN, stdout
    
    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.Threshold=WARN
    log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout
    
    log4j.logger.mylogger=DEBUG,logfile
    log4j.appender.logfile=org.apache.log4j.DailyRollingFileAppender
    log4j.appender.logfile.DatePattern=${roll.pattern.daily}
    log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
    log4j.appender.logfile.layout.ConversionPattern=%d{${datestamp}} [%t] %-5p %C{2} - %m%n
    log4j.appender.logfile.File=mylogfile.log


I want **mylogger** DEBUG messages to be send to the **logfile** appender, but I also want **mylogger** INFO messages to be sent to the **stdout** appender (but for all other loggers only WARN ings). Using the Threshold to limit stdout to WARN restricts the output of **mylogger**.


  [1]: https://stackoverflow.com/questions/1839647/how-to-configure-log4j-to-log-different-log-levels-to-different-files-for-the-sam

Log Level per appender for a single Logger

Is it possible to configure different log levels for a single Logger based on the appender?
I realize this is similar to this <a href="https://stackoverflow.com/questions/1839647/how-to-configure-log4j-to-log-different-log-levels-to-different-files-for-the-sam" target="_blank" rel="noopener noreferrer">question</a>, and this is as far as I had already got myself, but the problem with this is that the threshold applies to all loggers that log to that appender, whereas I only want the threshold to apply to a single logger.
i.e. So far I have something like this:
<pre><code class="hljs language-ini">log4j.rootLogger=WARN, stdout

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Threshold=WARN
log4j.appender.stdout.layout=org.apache.log4j.SimpleLayout

log4j.logger.mylogger=DEBUG,logfile
log4j.appender.logfile=org.apache.log4j.DailyRollingFileAppender
log4j.appender.logfile.DatePattern=${roll.pattern.daily}
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d{${datestamp}} [%t] %-5p %C{2} - %m%n
log4j.appender.logfile.File=mylogfile.log
</code></pre>
I want mylogger DEBUG messages to be send to the logfile appender, but I also want mylogger INFO messages to be sent to the stdout appender (but for all other loggers only WARN ings). Using the Threshold to limit stdout to WARN restricts the output of mylogger.

Java has the `transient`keyword. Why does JPA have `@Transient` instead of simply using the already existing java keyword?


Why does JPA have a @Transient annotation?

I&#39;m wondering if there is a recommended way of doing deep clone/copy of instance in java.

I have 3 solutions in mind, but I can have miss some,  and I&#39;d like to have your opinion

edit: include Bohzo propositon and refine question: it&#39;s more about deep cloning than shallow cloning.

Do it yourself:
---------------
code the clone by hand properties after properties and check that mutable instances are cloned too.   
**pro:**  
- control of what will be performed  
- quick execution  
**cons:**   
- tedious to write and maintain  
- bug prone (copy/paste failure, missing property, reassigned mutable property) 

Use reflection:
---------------
With your own reflection tools or with an external helper (like jakarta common-beans) it is easy to write a generic copy method that will do the job in one line.  
**pro:**  
- easy to write  
- no maintenance  
**cons:**  
- less control of what happens  
- bug prone with mutable object if the reflection tool does not clone sub objects too  
- slower execution

Use clone framework:
-------------------
Use a framework that do it for you, like :  
[commons-lang SerializationUtils][1]  
[Java Deep Cloning Library][2]  
[Dozer][3]  
[Kryo][4]

**pro:**  
- same as reflection   
- more control over what will be exactly be cloned.  
**cons:**   
- every mutable instance is fully cloned, even at the end of the hierarchy   
- could be very slow to execute

Use bytecode instrumentation to write clone at runtime
------------------------------------------------------
[javassit][5], [BCEL][6] or [cglib][7] might be use to generate a dedicated cloner as fast as one hand writed. Someone knows a lib using one of these tools for this purpose ?

What I have missed here ?  
Which one would you recommend ?

Thanks.
 


  [1]: http://commons.apache.org/proper/commons-lang/javadocs/api-3.0.1/org/apache/commons/lang3/SerializationUtils.html
  [2]: https://github.com/kostaskougios/cloning
  [3]: http://dozer.sourceforge.net/documentation/about.html
  [4]: https://github.com/EsotericSoftware/kryo
  [5]: http://www.jboss.org/javassist
  [6]: http://jakarta.apache.org/bcel/index.html
  [7]: http://cglib.sourceforge.net/

Java: recommended solution for deep cloning/copying an instance

Unfortunately, Java has no syntax for multi-line string literals. No problem if the IDE makes it easy to work with constructs like 

      String x = &quot;CREATE TABLE TEST ( \n&quot;
                 + &quot;A INTEGER NOT NULL PRIMARY KEY, \n&quot;
                ...

What is the fastest way to paste a multi-line String from the clipboard into Java source using Eclipse (in a way that it automatically creates code like the above).

Paste a multi-line Java String in Eclipse

From the [Java tutorial][1]:


&gt;Finally, there&#39;s also a special kind of literal called a *class literal*, formed by taking a type name and appending &quot;`.class`&quot;; for example, `String.class`. This refers to the object (of type `Class`) that represents the type itself.

To what type of variable can this literal be assigned to?

Please give a small example if possible.

  [1]: http://docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

What is a class literal in Java?

Any ideas what could be the cause of this?

&gt; Unable to locate Spring
&gt; NamespaceHandler for XML schema
&gt; namespace
&gt; [http://www.springframework.org/schema/security]

    org.springframework.web.context.ContextLoader initWebApplicationContext: Context initialization failed
    org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]
    Offending resource: ServletContext resource [/WEB-INF/applicationContext.xml]

This is my applicationContext.xml:

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;UTF-8&quot;?&gt;
    &lt;beans:beans xmlns=&quot;http://www.springframework.org/schema/security&quot;
        xmlns:xsi=&quot;http://www.w3.org/2001/XMLSchema-instance&quot;
        xmlns:beans=&quot;http://www.springframework.org/schema/beans&quot;
        xmlns:context=&quot;http://www.springframework.org/schema/context&quot;
        xsi:schemaLocation=&quot;http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
            http://www.springframework.org/schema/context 
            http://www.springframework.org/schema/context/spring-context-3.0.xsd
            http://www.springframework.org/schema/security
            http://www.springframework.org/schema/security/spring-security-3.0.xsd&quot;&gt;
    ...
    &lt;/beans:beans&gt;

In my pom.xml I have:

    &lt;dependency&gt;
        &lt;groupId&gt;org.springframework.security&lt;/groupId&gt;
        &lt;artifactId&gt;spring-security-core&lt;/artifactId&gt;      
        &lt;version&gt;3.0.1.RELEASE&lt;/version&gt;
    &lt;/dependency&gt;
    &lt;dependency&gt;
        &lt;groupId&gt;org.springframework.security&lt;/groupId&gt;
        &lt;artifactId&gt;spring-security-openid&lt;/artifactId&gt;
        &lt;version&gt;3.0.1.RELEASE&lt;/version&gt;
    &lt;/dependency&gt;



Spring 3.0 - Unable to locate Spring NamespaceHandler for XML schema namespace [http://www.springframework.org/schema/security]

I&#39;d like to have loglevel TRACE (5) for my application, as I don&#39;t think that `debug()` is sufficient. Additionally `log(5, msg)` isn&#39;t what I want. How can I add a custom loglevel to a Python logger?

I&#39;ve a `mylogger.py` with the following content:

    import logging
    
    @property
    def log(obj):
        myLogger = logging.getLogger(obj.__class__.__name__)
        return myLogger

In my code I use it in the following way:

    class ExampleClass(object):
        from mylogger import log
    
        def __init__(self):
            &#39;&#39;&#39;The constructor with the logger&#39;&#39;&#39;
            self.log.debug(&quot;Init runs&quot;)

Now I&#39;d like to call `self.log.trace(&quot;foo bar&quot;)`

**Edit** (Dec 8th 2016): I changed the accepted answer to [pfa&#39;s][1] which is, IMHO, an excellent solution based on the very good proposal from Eric S.


  [1]: https://stackoverflow.com/a/13638084/600110

How to add a custom loglevel to Python&#39;s logging facility

**I am looking for ideas on an efficient way to implement a log window for a windows forms application. In the past I have implemented several using TextBox and RichTextBox but I am still not totally satisfied with the functionality.**

This log is intended to provide the user with a recent history of various events, primarily used in data-gathering applications where one might be curious how a particular transaction completed. In this case, the log need not be permanent nor saved to a file.

First, some proposed requirements:

 - Efficient and fast; if hundreds of lines are written to the log in quick succession, it needs to consume minimal resources and time.
 - Be able to offer a variable scrollback of up to 2000 lines or so. Anything longer is unnecessary.
 - Highlighting and color are preferred. Font effects not required.
 - Automatically trim lines as the scrollback limit is reached.
 - Automatically scroll as new data is added.
 - Bonus but not required: Pause auto-scrolling during manual interaction such as if the user is browsing the history.

What I have been using so far to write and trim the log:

I use the following code (which I call from other threads):

    // rtbLog is a RichTextBox
    // _MaxLines is an int
    public void AppendLog(string s, Color c, bool bNewLine)
    {
    	if (rtbLog.InvokeRequired)
    	{
    		object[] args = { s, c, bNewLine };
    		rtbLog.Invoke(new AppendLogDel(AppendLog), args);
    		return;
    	}
    	try
    	{
    		rtbLog.SelectionColor = c;
    		rtbLog.AppendText(s);
    		if (bNewLine) rtbLog.AppendText(Environment.NewLine);
    		TrimLog();
    		rtbLog.SelectionStart = rtbLog.TextLength;
    		rtbLog.ScrollToCaret();
    		rtbLog.Update();
    	}
    	catch (Exception exc)
    	{
    		// exception handling
    	}
    }
    
    private void TrimLog()
    {
    	try
    	{
    		// Extra lines as buffer to save time
    		if (rtbLog.Lines.Length &lt; _MaxLines + 10)
    		{
    			return;
    		}
    		else
    		{
    			string[] sTemp = rtxtLog.Lines;
    			string[] sNew= new string[_MaxLines];
    			int iLineOffset = sTemp.Length - _MaxLines;
    			for (int n = 0; n &lt; _MaxLines; n++)
    			{
    			    sNew[n] = sTemp[iLineOffset];
    			    iLineOffset++;
    			}
    			rtbLog.Lines = sNew;
    		}
    	}
    	catch (Exception exc)
    	{
    		// exception handling
    	}
    }

The problem with this approach is that whenever TrimLog is called, I lose color formatting. With a regular TextBox this works just fine (with a bit of modification of course).

Searches for a solution to this have never been really satisfactory. Some suggest to trim the excess by character count instead of line count in a RichTextBox. I&#39;ve also seen ListBoxes used, but haven&#39;t successfully tried it.

Elegant Log Window in WinForms C#

Where can I view Tomcat log files in Eclipse?

For some reason my Tomcat installation/log folder is always empty.

BTW, does Tomcat dump to the log file after a while or is it immediate?

Where can I view Tomcat log files in Eclipse?

Why doesn&#39;t [logcat][1] show anything in my Android (while developing apps with Eclipse)?

It just doesn&#39;t print anything. It&#39;s empty.

  [1]: http://developer.android.com/guide/developing/tools/logcat.html


Why doesn&#39;t logcat show anything in my Android?

How to disable [logging](http://docs.python.org/library/logging.html) on the standard error stream in Python? This does not work:

```python
import logging

logger = logging.getLogger()
logger.removeHandler(sys.stderr)
logger.warning(&#39;foobar&#39;)  # emits &#39;foobar&#39; on sys.stderr
```

How to disable logging on the standard error stream?

I am using log4j with tomcat. When I log exceptions in my JSPs, servlets:

    private Logger _log = Logger.getLogger(this.getClass());
    ...
    try{...} catch (Exception e) {
        _log.error(&quot;Error refreshing all prices&quot;, e);
    }

I only get the first line of the exception, without a stacktrace. 

&gt; 17-Feb 17:37:45 ERROR AutoContrib:175 - Exception while publishing csv file:
java.lang.ArrayIndexOutOfBoundsException


Not very helpful at all!

My log4j.properties file (/tomcat/common/classes/log4j.properties) looks like this:

    log4j.appender.stdout=org.apache.log4j.ConsoleAppender
    log4j.appender.stdout.Target=System.out
    log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
    log4j.appender.stdout.layout.ConversionPattern=%d{dd-MMM HH:mm:ss} %5p %c{1}:%L - %m%n
    log4j.appender.stdout.threshold=info

    log4j.appender.file=org.apache.log4j.RollingFileAppender
    log4j.appender.file.maxFileSize=5000KB
    log4j.appender.file.maxBackupIndex=10
    log4j.appender.file.File=${catalina.home}/logs/web.log
    log4j.appender.file.layout=org.apache.log4j.PatternLayout
    log4j.appender.file.layout.ConversionPattern=%d{dd-MMM HH:mm:ss} %5p %c{1}:%L - %m%n
    log4j.appender.file.threshold=info

    log4j.rootLogger=debug, stdout, file

log4j not printing the stacktrace for exceptions

What is the difference between `logger.debug` and `logger.info` ?

When will `logger.debug` be printed?

Difference between logger.info and logger.debug

I am looking for some kind of analyzer tool for log files generated by log4j files. I am looking something more advanced than _grep_? What are you using for log file analysis?

I am looking for following kinds of features:

- The tool should tell me how many time a given log statement or a stack trace has occurred, preferably with support for some kinds of patterns (eg. number of log statements matching &#39;User [a-z]* logged in&#39;). 
- Breakdowns by log level (how many INFO, DEBUG lines) and by class that initiated the log message would be nice.
- Breakdown by date (how many log statements in given time period)
- What log lines occur commonly together?
- Support for several files since I am using log rolling
- Hot spot analysis: find if there is a some time period when there is unusually high number of log statements
- Either command-line or GUI are fine
- Open Source is preferred but I am also interested in commercial offerings

My log4j configuration uses org.apache.log4j.PatternLayout with pattern `%d %p %c - %m%n` but that could be adapted for analyzer tool.

Is there a log file analyzer for log4j files?

When using log4j, the `Logger.log(Priority p, Object message)` method is available and can be used to log a message at a log level determined at runtime. We&#39;re using this fact and [this tip][1] to redirect stderr to a logger at a specific log level.

slf4j doesn&#39;t have a generic `log()` method that I can find. Does that mean there&#39;s no way to implement the above?


  [1]: http://www.mail-archive.com/log4j-user@logging.apache.org/msg05005.html

Setting log level of message at runtime in slf4j

I use log4j and would like to route the output of certain Loggers to specific files. 

I already have multiple appenders in place. Now, to make debugging easier, I want to tell log4j that the output generated by a specific class (e.g. foo.bar.Baz) should be written to a specific log file.

Can this be done?

Content Type	Original Author	Original Content on Stackoverflow
Question	Joel	View Question on Stackoverflow
Solution 1 - Java	Joel	View Answer on Stackoverflow

Log Level per appender for a single Logger

Java Problem Overview

Java Solutions

Solution 1 - Java

How to start Solr automatically?

load json into variable

Attributions