Just use `Analyze | Inspect Code` with appropriate inspection enabled (**Unused declaration** under **Declaration redundancy** group).

Using IntelliJ 11 CE you can now &quot;Analyze | Run Inspection by Name ... | Unused declaration&quot;

In newer versions of IntelliJ it&#39;s under **Code -&gt; Analyze Code -&gt; Run Inspection by Name**.

In IntelliJ versions before that, you should run it from **Analyze -&gt; Run Inspection By Name**:

[![enter image description here][1]][1]

Than, pick **Unused declaration**:

[![enter image description here][2]][2]

And finally, **uncheck** the **Include test sources**:

[![enter image description here][3]][3]


  [1]: https://i.stack.imgur.com/ngUH5m.png
  [2]: https://i.stack.imgur.com/DGDd6m.png
  [3]: https://i.stack.imgur.com/1Ls86m.png

After you&#39;ve run the Inspect by Name, select all the locations, and make use of the *Apply quick fixes to all the problems* drop-down, and use either (or both) of *Delete unused parameter(s)* and *Safe Delete*.

Don&#39;t forget to hit *Do Refactor* afterwards.

Then you&#39;ll need to run another analysis, as the refactored code will no doubt reveal more unused declarations.

[![Apply quick fixes to all the problems][1]][1]


  [1]: https://i.stack.imgur.com/QmUrH.png

Is there a quick way to find all of the implementations of, not references to, an interface&#39;s method/property/etc?  Here&#39;s some sample code: 

    public class SomeClass : IBaseClass
    {
      public Int32 GetInt()
      {
         return 1;
      }
    }
    
    public interface IBaseClass
    {
      public Int32 GetInt();
    }
    
    public class SomeOtherClass
    {
      IBaseClass _someClass;
      private TestMethod()
      {
        _someClass = new SomeClass();
        _someClass.GetInt();
      }
    }

I want to quickly get to SomeClass.GetInt() while reviewing SomeOtherClass.TestMethod().  If I right click on _someClass.GetInt() and click &#39;Go To Definition&#39;, it takes me to the interface.  If I click &#39;Find All References&#39;, I could potentially see a list of all uses ... not just the classes that implement the GetInt() method.  

Is there a faster way to find this?  Any tips from other developers?  We are using D.I. for most of our dependencies, which means that tracing through deeply nested code takes *forever*.

How do you quickly find the implementation(s) of an interface&#39;s method?

I found some codes for quitting an Android application programmatically. By calling any one of the following codes in onDestroy(), will it quit application entirely?    

 1. `System.runFinalizersOnExit(true)`  
                (OR)
 2. `android.os.Process.killProcess(android.os.Process.myPid());`

I don&#39;t want to run my application in background after clicking quit button. 
Please inform me if I can use any one of these codes to quit my app? If so, which code can I use? Is it good way to quit the app in Android?

How to quit android application programmatically

When I am in a .java file the unused code is usually grayed out or has a green underline saying this code will probably (probably because of some weird JNI/Reflection corner cases) be unused. But I have this project with thousands of Java files and I want to find ALL INSTANCES of such probable-unused codes. How can I do that in IntelliJ IDEA?

How to use IntelliJ IDEA to find all unused code?

<p>When I am in a .java file the unused code is usually grayed out or has a green underline saying this code will probably (probably because of some weird JNI/Reflection corner cases) be unused. But I have this project with thousands of Java files and I want to find ALL INSTANCES of such probable-unused codes. How can I do that in IntelliJ IDEA?</p>


Java is an optional package on the latest versions of macOS.  

Yet once installed it appears like the **JAVA_HOME** environment variable is **not set properly**.



Where is JAVA_HOME on macOS Mojave (10.14) to Lion (10.7)?

I know that when I read the answer to this I will see that I have overlooked something
that was under my eyes. But I have spent the last 30 minutes trying to figure it out myself
with no result.

So, I was writing a program in Java 6 and discovered some (for me) strange feature.
In order to try and isolate it, I have made two small examples.
I first tried the following method:

    private static int foo()
    {
        return null;
    }

and the compiler refused it: Type mismatch: cannot convert from null to int.

This is fine with me and it respects the Java semantics I am familiar with.
Then I tried the following:

    private static Integer foo(int x)
    {
        if (x &lt; 0)
        {
            return null;
        }
        else
        {
            return new Integer(x);
        }
    }

    private static int bar(int x)
    {
        Integer y = foo(x);

        return y == null ? null : y.intValue();
    }

    private static void runTest()
    {
        for (int index = 2; index &gt; -2; index--)
        {
            System.out.println(&quot;bar(&quot; + index + &quot;) = &quot; + bar(index));
        }
    }

This compiles with no errors! But, in my opinion, there should be a type conversion error
in the line

        return y == null ? null : y.intValue();

If I run the program I get the following output:

    bar(2) = 2
    bar(1) = 1
    bar(0) = 0
    Exception in thread &quot;main&quot; java.lang.NullPointerException
        at Test.bar(Test.java:23)
        at Test.runTest(Test.java:30)
        at Test.main(Test.java:36)

Can you explain this behaviour?

**Update**

Thank you very much for the many clarifying answers. I was a bit worried because
this example did not correspond to my intuition. One thing that disturbed me was
that a null was being converted to an int and I was wondering what the result would
be: 0 like in C++? That would hae been very strange.
Good that the conversion is not possible at runtime (null pointer exception).

Conversion from null to int possible?

I&#39;m currently trying to make a program that conjugates verbs into Spanish.  I&#39;ve created a Hash Table that contains a key and an instantiation of the object Verb.  The key is a string that has the infinitive form of the verb (for example, &quot;hablar&quot;).  This is the code that I have so far for the hash map:


    public class VerbHashMap {
	
	    HashMap&lt;String, Verb&gt; verbHashMap;
	
	    public VerbHashMap(){
	      	verbHashMap = new HashMap();
	    }	
    }

Each verb&#39;s key in the HashMap is based on the infinitive form of the verb.  For example, the string &quot;hablar&quot; is the key for a Spanish verb.  The class Verb has a method called getInfinitive() which returns a string that contains the infinitive form of the verb.

	public boolean addVerb(Verb verb){
		if(verbHashMap.containsValue(verb.getInfinitive()){
			return false;
		}
		else{
			verbHashMap.put(verb.getInfinitive(), verb);
			return true;
		}
	}


The question is what is the most efficient way to create a method that returns a list of all the verbs in the Hash Map in alphabetical order?  Should I have the method return an ArrayList which includes the keys of all the objects in the Hash Map?  Or is there a much more efficient way to go about this?



How to return a list of keys from a Hash Map?

Is there a way to get the android app version from code? Is it possible to do so?

Get application version programmatically in android

I want to use the count from the JSTL forEach loop, but my code doesnt seem to work.

    &lt;c:forEach items=&quot;${loopableObject}&quot; var=&quot;theObject&quot; varStatus=&quot;theCount&quot;&gt;
        &lt;div id=&quot;divIDNo${theCount}&quot;&gt;
        &lt;/div&gt;
    &lt;/c:forEach&gt;

produces 

    &lt;div id=&quot;divIDNojavax.servlet.jsp.jstl.core.LoopTagSupport$1Status@5570e2&quot; &gt;



Use JSTL forEach loop&#39;s varStatus as an ID

I work with a lot of calculation code written in [tag:C++] with high-performance and low memory overhead in mind. It uses STL containers (mostly `std::vector`) a lot, and iterates over that containers almost in every single function.

The iterating code looks like this:

    for (int i = 0; i &lt; things.size(); ++i)
    {
        // ...
    }

But it produces the **signed/unsigned mismatch** warning (**C4018 in Visual Studio**).

Replacing `int` with some `unsigned` type is a problem because we frequently use `OpenMP` pragmas, and it requires the counter to be `int`.

I&#39;m about to suppress the (hundreds of) warnings, but I&#39;m afraid I&#39;ve missed some elegant solution to the problem.

**On iterators**. I think iterators are great when applied in appropriate places. The code I&#39;m working with will _never_ change random-access containers into `std::list` or something (so iterating with `int i` is already container agnostic), and will _always_ need the current index. And all the additional code you need to type (iterator itself and the index) just complicates matters and obfuscates the simplicity of the underlying code.

How do I deal with &quot;signed/unsigned mismatch&quot; warnings (C4018)?

If I want to override some methods I currently right-click on the class name, select &quot;Source&quot; -&gt; &quot;Override/impl...&quot;.

Is there a shortcut or another way to do this quicker in Eclipse?

How to quickly implement/override methods in Eclipse?

As I&#39;ve pointed out - [here](https://stackoverflow.com/questions/5587140/any-tutorial-on-how-to-use-clang-for-syntax-highlighting-and-code-completion/7250322#7250322) - it seems clang&#39;s [libclang]() should be great for implementing the hard task that is C/C++ code analysis and modifications ([check out video presentation and slides](https://stackoverflow.com/questions/5587140/any-tutorial-on-how-to-use-clang-for-syntax-highlighting-and-code-completion/7250322#7250322)).

Do you know of **any** C/C++ refactoring tool based on libclang ?

&quot;Any&quot; includes even simple alpha state project, with support of one refactoristation technique. It can be without preprocessor support. As an example of the functionally about which I&#39;m talking: changing method names, whether it supports multiple files or only one file at a time. You might be wondering what the goal is of asking for even small working examples My thought is that *creating a list of code examples and small tools that are in one place will provide a better resource to learn how to implement refactorisation with libclang*. I believe that from simple projects might grow bigger projects - in a proper opensource manner :).

any C/C++ refactoring tool based on libclang? (even simplest &quot;toy example&quot; )

I have a method that takes 30 parameters.  I took the parameters and put them into one class, so that I could just pass one parameter (the class) into the method.  Is it perfectly fine in the case of refactoring to pass in an object that encapsulates all the parameters even if that is all it contains.

Is it OK to have a class with just properties for refactoring purposes?

Of course the fact that you can refactor on IDEs is priceless for many, I hardly ever do it when I am coding but I may try to do it when editing some one else&#39;s source. How do you accomplish such a trivial task across multiple files in Vim?

I found [this plugin](https://github.com/ecomba/vim-ruby-refactoring) for refactoring Ruby, but how about &quot;any&quot; language?

Refactoring in Vim

Pressing Shift+F6 seems only to rename the last directory.             
**For example**, in the project `com.example.test` it will offer to rename test only. The same applies if I navigate to package name in `.java` or Manifest file and press Shift+F6.                           

So is there a way to rename the package?

How do I rename the android package name?

In Eclipse, when hovering over a method, variable, etc. a tooltip is displayed with the corresponding JavaDocs. Is there such a feature in IntelliJ?

IntelliJ show JavaDocs tooltip on mouse over

IntelliJ IDEA 10.5.1 is reporting zero usages for all method, classes etc. 

Can I force IntelliJ to rebuild the project indexes?



Rebuild IntelliJ project indexes

For some reason, dragging the mouse cursor started doing block selects instead of the normal line select mode:

![enter image description here][1]

(Please ignore the fact that this image is from Visual Studio and not IntelliJ)

I tried pressing scroll-lock, pressing and releasing the alt/ctrl/shift keys, but still selecting doesn&#39;t revert to the normal &quot;select full lines&quot; mode. When I click and hold, then drag the mouse, I get a block (rectangle) selection.

Do you know how to undo this?

P.S. I&#39;m running IntelliJ 9 on Ubuntu.

P.S. Holding SHIFT and pressing the up arrow button also does block select instead of normal multiline select.

  [1]: http://i.stack.imgur.com/70bmw.png

How do I turn off mouse block selection in IntelliJ?

How to enable remote debugging from IntelliJ with Tomcat?

Remote Debugging in IntelliJ Tomcat

In my Rails app, I use `Rubocop` to check for problems. Today it gave me an error like this : `Assignment Branch Condition size for show is too high`. Here&#39;s my code :

    def show
      @category = Category.friendly.find(params[:id])
      @categories = Category.all
      @search = @category.products.approved.order(updated_at: :desc).ransack(params[:q])
      @products = @search.result.page(params[:page]).per(50)
      rate
    end

What does this mean and how can I fix it?

What is meant by &#39;Assignment Branch Condition Size too high&#39; and how to fix it?

In Google Chrome&#39;s developer tools, when I select an element, I see     `==$0` next to the selected element. What does that mean?

[![Screenshot][1]][1]

  [1]: http://i.stack.imgur.com/C2eGI.jpg


Content Type	Original Author	Original Content on Stackoverflow
Question	pathikrit	View Question on Stackoverflow
Solution 1 - Java	CrazyCoder	View Answer on Stackoverflow
Solution 2 - Java	Johnny	View Answer on Stackoverflow
Solution 3 - Java	Orwellophile	View Answer on Stackoverflow

How to use IntelliJ IDEA to find all unused code?

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Solution 3 - Java

How to quit android application programmatically

How do you quickly find the implementation(s) of an interface's method?

Attributions