Intellij IDEA&#39;s Expression Evaluation dialog has a button to enable *Code Fragment Mode*, which permits multi-statement evaluations. (I&#39;m using version 9.0.2 of the Ultimate Edition.)

Same as @Noel answer, but some more details. First of all, *Expression Evaluation* (&lt;kbd&gt;ALT&lt;/kbd&gt; + &lt;kbd&gt;F8&lt;/kbd&gt;) can be enabled **only in debug mode**. 

![enter image description here][1]


![enter image description here][2]


  [1]: http://i.stack.imgur.com/LioJ8.jpg
  [2]: http://i.stack.imgur.com/bIFfh.jpg

**IntelliJ IDEA 13** Community Edition, Windows:

1. Go to **Debug mode** and run the application
2. Go to **Evaluate Expression**:

 ![enter image description here][1]

 or right click in the editor area:

 ![enter image description here][2]

3. Go to **Code Fragment Mode**
 ![enter image description here][3]

4. Type your statements and click on **Evaluate**
 ![enter image description here][4]


  [1]: http://i.stack.imgur.com/YcAJ2.png
  [2]: http://i.stack.imgur.com/TFrJT.png
  [3]: http://i.stack.imgur.com/ewkFF.png
  [4]: http://i.stack.imgur.com/9a0eG.png

FYI for anyone looking for this in 2019: I tried to do this in IntelliJ IDEA 2019.1 (Ultimate Edition) but couldn&#39;t find Code Fragment Mode button in the Expression Evaluation Dialog.

As documented [here][1]: It is now the tiny two arrows pointing away from each other diagonally at the end of the expression box.

[![enter image description here][2]][2]


  [1]: https://intellij-support.jetbrains.com/hc/en-us/community/posts/115000664524--Code-Fragment-button-missing
  [2]: https://i.stack.imgur.com/Iy5po.png

You can write code in alt-f8.. but you have to do it only 1 line at a time. If you do a return, your code will return when you hit next (I think).  It isn&#39;t ideal though...

In V2 there was a way to limit panning/dragging so the map stays within certain bounds. How is that done in V3? 

Let&#39;s say I want the users to only look at Europe. I&#39;ve already limited the zoom, but if I allow dragging (which I have to in this case, for other reasons) then the user can pan beyond the area I want to show.

Please give working example or code snippet - I&#39;m not an expert coder... 

How do I limit panning in Google maps API V3?

I have been using `Math.Round(myNumber, MidpointRounding.ToEven)` in C# to do my server-side rounding, however, the user needs to know &#39;live&#39; what the result of the server-side operation will be which means (avoiding an [Ajax][1] request) creating a JavaScript method to replicate the `MidpointRounding.ToEven` method used by C#.

MidpointRounding.ToEven is Gaussian/[banker&#39;s rounding][2], a very common rounding method for accounting systems described [here][3].

Does anyone have any experience with this? I have found examples online, but they do not round to a **given** number of decimal places...

  [1]: http://en.wikipedia.org/wiki/Ajax_%28programming%29
  [2]: https://en.wikipedia.org/wiki/Rounding#Round_half_to_even
  [3]: http://en.wikipedia.org/wiki/Rounding#Round_half_to_even


Gaussian/banker&#39;s rounding in JavaScript

I&#39;m using IntelliJ 9 and I&#39;m curious if there is any IntelliJ equivalent of the Visual Studio &#39;immediate&#39; debug window.  There is selecting the desired expression in the editor, then &lt;kbd&gt;ALT&lt;/kbd&gt;-&lt;kbd&gt;F8&lt;/kbd&gt; to evaluate the expression, but I&#39;d like to be able to write code in a window that interacts with what I am currently debugging (if that&#39;s even possible).

Having breakpoints that log messages to the console is helpful, but I&#39;d like to do more than that if I can.

&#39;Immediate&#39; window for IntelliJ

<p>I'm using IntelliJ 9 and I'm curious if there is any IntelliJ equivalent of the Visual Studio 'immediate' debug window.  There is selecting the desired expression in the editor, then <kbd>ALT</kbd>-<kbd>F8</kbd> to evaluate the expression, but I'd like to be able to write code in a window that interacts with what I am currently debugging (if that's even possible).</p>
<p>Having breakpoints that log messages to the console is helpful, but I'd like to do more than that if I can.</p>


Ok so this is probably a trivial question but I&#39;m having trouble visualizing and understanding the differences and when to use each. I&#39;m also a little unclear as to how concepts like uni-directional and bi-directional mappings affect the one-to-many/many-to-many relationships. I&#39;m using Hibernate right now so any explanation that&#39;s ORM related will be helpful. 

As an example let&#39;s say I have the following set-up:

    public class Person{
        private Long personId;
        private Set&lt;Skill&gt; skills;
        //Getters and setters
    }
    
    public class Skill{
        private Long skillId;
        private String skillName;
        //Getters and setters
    }

So in this case what kind of mapping would I have? Answers to this specific example are definitely appreciated but I would also really like an overview of when to use either one-to-many and many-to-many and when to use a join table versus a join column and unidirectional versus bidirectional.

Difference Between One-to-Many, Many-to-One and Many-to-Many?

I have Java app that takes data from external app. Incoming JSONs are in Strings. I would like to parse that Strings and create BSON objects.

Unfortunate I can&#39;t find API for that in Java&#39;s BSON implementation.

Do I have use external parser for that like GSON?

Creating BSON object from JSON string

I have seen many Android answers that suggest calling the garbage collector in some situations.

Is it a good practice to request the garbage collector in Android before doing a memory-hungry operation? If not, should I only call it if I get an `OutOfMemory` error?

Are there other things I should use before resorting to the garbage collector?

Garbage collector in Android

I&#39;m trying to timeout an *HttpSession* in Java. My container is WebLogic.

Currently, we have our session timeout set in the *web.xml* file, like this
&lt;!-- language: lang-xml --&gt;

    &lt;session-config&gt;
        &lt;session-timeout&gt;15&lt;/session-timeout&gt;
    &lt;/session-config&gt;

Now, I&#39;m being told that this will terminate the session (or is it all sessions?) in the 15th minute of use, regardless their activity.

I&#39;m wondering if this approach is the correct one, or should I programatically set the time limit of inactivity by
&lt;!-- language: lang-java --&gt;

    session.setMaxInactiveInterval(15 * 60); //15 minutes

I don&#39;t want to drop all sessions at 15 minutes, only those that have been inactive for 15 minutes.

Are these methods equivalent? Should I favour the *web.xml* config?


SessionTimeout: web.xml vs session.maxInactiveInterval()

The question from the title in code:

    @Transactional (readonly = true)
    public interface FooService {
       void doSmth ();
    }
    
    
    public class FooServiceImpl implements FooService {
       ...
    }

vs

    public interface FooService {
       void doSmth ();
    }
    
    @Transactional (readonly = true)
    public class FooServiceImpl implements FooService {
       ...
    }



Where should I put @Transactional annotation: at an interface definition or at an implementing class?

When the Java application is hanging, you don&#39;t even know the use case that is leading to this and want to investigate, I understand that thread dumps can be useful.

But how can we easily derive useful data from the thread dumps to find where the problem is? The server application that I&#39;ve been working with produces very long thread dumps, because it is an EJB architecture and thread dumps contains many container threads that I&#39;m not sure I should be looking at (i.e. threads that are not running my application code, but JBoss&#39;s code). 

Yesterday I tried the [Thread Dump Analyzer][1] tool. The tool is definitely better than looking at the raw thread dumps in a text editor, because you can filter out threads that you&#39;re not interested in, see the thread list, click on a thread to see its details, compare thread dumps to find long running threads, etc.

But there&#39;s still too much data to analyse - almost 300 threads. I don&#39;t know of any criteria that I could use to filter out all the JBoss threads, in which I&#39;m not interested. I&#39;m not sure if I should be looking at threads that are currently in &quot;runnable&quot; state only or if &quot;waiting on condition&quot; and &quot;in Object.wait&quot; are also important.

What&#39;s the approach that you would normally follow and tools that you would in general use? 


  [1]: http://java.net/projects/tda

Thread Dump Analysis Tool / Method

How can I set up `gdb` so that it saves the command history? When starting a new `gdb` session I&#39;d like to use the arrow up keys to access the commands of the previous sessions. 





How can I make gdb save the command history?

There are two ways to increase the usefulness of debugging information instead of seeing `{MyNamespace.MyProject.MyClass}` in the debugger. 

These are the use of [`DebuggerDisplayAttribute`][1] and the `ToString()` method.

    using System.Diagnostics;
    ...

    [DebuggerDisplay(&quot;Name = {Name}&quot;)]
    public class Person
    {
        public string Name;
    }

or 

    public class Person
    {
        public string Name;
        public override string ToString()
        {
            return string.Format(&quot;Name = {0}&quot;, Name);
        }
    }


Is there any reason to prefer one to the other? Any reason not to do both? Is it purely personal preference?


  [1]: https://docs.microsoft.com/en-us/dotnet/api/system.diagnostics.debuggerdisplayattribute

C# debugging: [DebuggerDisplay] or ToString()?

The most important things I want to know are the device type, the OS version, if it has a hardware keyboard and maybe the screen resolution. but if you know other useful debug information please add them :)

I found this for the OS version:

    string += &quot;OS Version: &quot; + System.getProperty(&quot;os.version&quot;);

How do I get the other properties?

How to detect system information like os or device type

This happens to me pretty often.  For example, right now I have the debugger stopped at a breakpoint in a method . . . and it isn&#39;t displaying any variable values at all.  Other times, it displays some, but not others.

Can anyone explain?

Xcode debugger sometimes doesn&#39;t display variable values?

The terms &quot;jta-datasource&quot; and &quot;resource-local datasource&quot; are a little vague to me. I&#39;m putting down what I am understanding ( or assuming ) and I&#39;d like you to say where I&#39;m right / wrong.

 - The same database can be referred to as a jta-datasource or as a resource local datasource
 - If mentioned as jta-datasource, then the beans / other classes can use JTA. Hence, UserTransaction interface
 - Cannot use [CMT][1] / [BMT][2] if the datasource is resource local 
 - If mentioned as resource local datasource, transactions are not JTA aware. Code can use EntityTransaction interface but not UserTransaction interface

Thanks!

    


  [1]: http://docs.oracle.com/javaee/6/tutorial/doc/bncij.html
  [2]: http://docs.oracle.com/javaee/6/tutorial/doc/bnciy.html

Difference between a &quot;jta-datasource&quot; and a &quot; resource-local &quot; datasource?

I&#39;m developing a Java enterprise application, currently doing Java EE security stuff to restrict access for particular functions to specific users. I configured the application server and everything, and now I&#39;m using the RolesAllowed-annotation to secure the methods:

    @Documented
    @Retention (RUNTIME)
    @Target({TYPE, METHOD})
    public @interface RolesAllowed {
        String[] value();
    }

When I use the annotation like this, it works fine:

    @RolesAllowed(&quot;STUDENT&quot;)
    public void update(User p) { ... }

But this is not what I want, as I have to use a String here, refactoring becomes hard, and typos can happen. So instead of using a String, I would like to use an Enum value as a parameter for this annotation. The Enum looks like this:

    public enum RoleType {
        STUDENT(&quot;STUDENT&quot;),
        TEACHER(&quot;TEACHER&quot;),
        DEANERY(&quot;DEANERY&quot;);

        private final String label;

        private RoleType(String label) {
            this.label = label;
        }

        public String toString() {
            return this.label;
        }
    }

So I tried to use the Enum as a parameter like this:

    @RolesAllowed(RoleType.DEANERY.name())
    public void update(User p) { ... }

But then I get the following compiler error, although Enum.name just returns a String (which is always constant, isn&#39;t it?).

&gt; The value for annotation attribute RolesAllowed.value must be a constant expression`

The next thing I tried was to add an additional final String to my Enum:

    public enum RoleType {
        ...
        public static final String STUDENT_ROLE = STUDENT.toString();
        ...
    }

But this also doesn&#39;t work as a parameter, resulting in the same compiler error:

    // The value for annotation attribute RolesAllowed.value must be a constant expression
    @RolesAllowed(RoleType.STUDENT_ROLE)

How can I achieve the behavior I want? I even implemented my own interceptor to use my own annotations, which is beautiful, but far too much lines of codes for a little problem like this.

**DISCLAIMER**

This question was originally a [Scala][1] question. I found out that Scala is not the source of the problem, so I first try to do this in Java.

  [1]: http://en.wikipedia.org/wiki/Scala_%28programming_language%29


Use Enum type as a value parameter for @RolesAllowed-Annotation

In a managed bean, `@PostConstruct` is called after the regular Java object constructor.

Why would I use `@PostConstruct` to initialize by bean, instead of the regular constructor itself?

Why use @PostConstruct?

What&#39;s the exact difference between `@JoinColumn` and `@PrimaryKeyJoinColumn`?

You use `@JoinColumn` for columns that are part of a foreign key. A typical column could look like (e.g. in a join table with additional attributes):

    @ManyToOne
    @JoinColumn(name = &quot;...&quot;)
    private OtherClass oc;

What happens if I promote the column to be a/the PK, too (a.k.a. identifying relationship)? As the column is now the PK, I must tag it with `@Id`:

    @Id
    @ManyToOne
    @JoinColumn(name = &quot;...&quot;)
    private OtherClass oc;

Now the question is:

Are `@Id` + `@JoinColumn` the same as just `@PrimaryKeyJoinColumn`?:

    @ManyToOne
    @PrimaryKeyJoinColumn(name = &quot;...&quot;)
    private OtherClass oc;

If not, what&#39;s `@PrimaryKeyJoinColumn` there for?

JPA: difference between @JoinColumn and @PrimaryKeyJoinColumn?

How can I set the charset with JAX-RS? I&#39;ve tried `@Produces(&quot;text/html; charset=UTF-8&quot;)` but that was ignored and only `text/html` was send with the HTTP header. I want to set the charset within a MessageBodyWriter, but don&#39;t want to extract the media type by analysing the @Produces annotation via reflection by myself.

How to set the charset with JAX-RS?

I have a JUnit run configuration to run all my unit tests. 

How can I bind a keyboard shortcut to the run of that JUnit config?

IntelliJ keyboard shortcut for a particular run configuration

I would like to create a script to modify my debug configuration in intellij. The path of tomcat changes, and i have to manually go into the run config and edit things. I have tried to find the place where intellij stores these settings to no avail.

**question**: does anyone know where IJ stores its run configuration 

intellij idea run configurations backup

I&#39;ve recently moved from Eclipse to IntelliJ. A challenge as I&#39;m a keyboard shortcut junkie, but that isn&#39;t what I&#39;m here about. 

I miss having the git branch name shown in the package/project view. 

Does anyone know of a way to configure IntelliJ to display what git branch the project is in, so I don&#39;t have to keep switching back to the terminal and checking.

Thanks.

IntelliJ and Git Branch Name

I have just installed IntelliJ 9.0.2 on a machine running 64-bit Ubuntu 10.04.

How do I get another window to put on my second screen?

I would like to have both an editor and some tool windows on both screens.

How do I set up IntelliJ on dual monitors?

I&#39;m finally making the voyage back to IntelliJ via Eclipse.  Currently my Eclipse is set up so that if I currently have a statement such as this (where ^ denotes where my cursor currently sits):

    foo.bar(&quot;hello&quot;^)

and I hit the semi-colon (;) key, it will automatically put the semi-colon at the end of the statement:

    foo.bar(&quot;hello&quot;);

Currently IntelliJ does this:

    foo.bar(&quot;hello&quot;;)

Meaning I will have to explicitly type the closing bracket before typing the semi-colon.

Not a huge problem obviously but I have found myself putting the semi-colon in the wrong place a few times today as I make the transition back to IntelliJ and thought that it may be more efficient (for both my fingers and brain) not to have to type the closing bracket.

Content Type	Original Author	Original Content on Stackoverflow
Question	Jon Onstott	View Question on Stackoverflow
Solution 1 - Java	Noel Ang	View Answer on Stackoverflow
Solution 2 - Java	om-nom-nom	View Answer on Stackoverflow
Solution 3 - Java	ROMANIA_engineer	View Answer on Stackoverflow
Solution 4 - Java	AzzamAziz	View Answer on Stackoverflow
Solution 5 - Java	bwawok	View Answer on Stackoverflow

'Immediate' window for IntelliJ

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Solution 3 - Java

Solution 4 - Java

Solution 5 - Java

Gaussian/banker's rounding in JavaScript

How do I limit panning in Google maps API V3?

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