&gt; It is just a shorthand for &quot;same as in declaration&quot;.

Some IDEs, e.g. IntelliJ use this too.

The files on disk do not have this notation, which is only a compaction in the IDE GUI.

If there wasn&#39;t a tilde, I&#39;d say, the code was already Java 7. [Java 7 allows the diamond operator][1] so this is/will be legal Java code:

    Map&lt;String, List&lt;String&gt;&gt; map = new HashMap&lt;&gt;();

(but - no tilde with this syntax)


  [1]: http://code.joejag.com/2009/new-language-features-in-java-7/

In IntelliJ IDEA, the `~` here:

    Set&lt;String&gt; associations = new LinkedHashSet&lt;~&gt;();

means `String`, which is the same as in the declaration on the left side.

I think that is shorthand to mean whatever the type is, in this case *OrderItem*.

How can I make a phone call programmatically on iPhone? I tried the following code but nothing happened:

    NSString *phoneNumber = mymobileNO.titleLabel.text;
    [[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneNumber]];



Make a phone call programmatically

Hypothetically, I have 5 string array objects:

    String[] array1 = new String[];
    String[] array2 = new String[];
    String[] array3 = new String[];
    String[] array4 = new String[];
    String[] array5 = new String[];

and I want another array object to contain those 5 string array objects. How do I do it? Can I put it in another array?

How to make an array of arrays in Java

I was reading through some JMockit examples and found this code:

    final List&lt;OrderItem&gt; actualItems = new ArrayList&lt;~&gt;();

What does the tilde in the generic identifier mean? I know it&#39;s the unary bitwise NOT operator, but I don&#39;t see an operand here.

Also, I tried compiling it and got an error. Am I just missing something?

What does a tilde in angle brackets mean when creating a Java generic class?

I was reading through some JMockit examples and found this code:
<pre><code class="hljs language-ini">final List&#x3C;OrderItem> actualItems = new ArrayList&#x3C;~>();
</code></pre>
What does the tilde in the generic identifier mean? I know it's the unary bitwise NOT operator, but I don't see an operand here.
Also, I tried compiling it and got an error. Am I just missing something?

I&#39;m using String.format() in Java trying to emulate the printf() control channel available in C. I understand how to specify that a string should be placed in a field which takes 20 characters, 5, 2 ... with 3 decimals, 2, etc.  However, the strings are printed right-aligned in their field.

How do I left-align the strings?

Here&#39;s an example of a possible output which I would like to modify to left-align `EXECUTING` and `CREATED` in their fields.

    Process PID: 25    Status: -----------       EXECUTING
    Process PID: 36    Status: READY-SUSPENDED
    Process PID:  4    Status: ----------------        CREATED

*note: consider &#39;-&#39; as an empty space

How can I left-align strings using String.format()?


What are the pro&#39;s and con&#39;s of calling out to a mutator from a constructor (if any)

i.e.:

    public MyConstructor(int x) {
      this.x = x;
    }

versus:

    public MyConstructor(int x) {
      setX(x);
    }
    
    public void setX(int x) {
      this.x = x;
    }

Do you have a preference?  (This is not homework, just looking at our coding standards doc where it says to always call out to mutators when setting instance var&#39;s in the constructor and I don&#39;t always to this)



calling setters from a constructor

I&#39;m trying to make a simple String to SHA1 converter in Java and this is what I&#39;ve got...

	public static String toSHA1(byte[] convertme) {
	    MessageDigest md = null;
		try {
			md = MessageDigest.getInstance(&quot;SHA-1&quot;);
		}
		catch(NoSuchAlgorithmException e) {
			e.printStackTrace();
		} 
	    return new String(md.digest(convertme));
	}

When I pass it `toSHA1(&quot;password&quot;.getBytes())`, I get `[�a�ɹ??�%l�3~��.` I know it&#39;s probably a simple encoding fix like UTF-8, but could someone tell me what I should do to get what I want which is `5baa61e4c9b93f3f0682250b6cf8331b7ee68fd8`? Or am I doing this completely wrong?

Java String to SHA1

Assume, I have a constant number of collections (e.g. 3 ArrayLists) as members of a class. Now, I want to expose all the elements to other classes so they can simply iterate over all elements (ideally, read only).
I&#39;m using guava collections and I wonder how I could use guava iterables/iterators to generate a logical view on the internal collections **without** making temporary copies.

Combine multiple Collections into a single logical Collection?

I&#39;m reading a file through a FileReader - the file is UTF-8 decoded (with BOM) now my problem is: I read the file and output a string, but sadly the BOM marker is outputted too. Why this occurs?

    fr = new FileReader(file);
    br = new BufferedReader(fr);
    	String tmp = null;
    	while ((tmp = br.readLine()) != null) {
    	String text;	
        text = new String(tmp.getBytes(), &quot;UTF-8&quot;);
    	content += text + System.getProperty(&quot;line.separator&quot;);
    }

output after first line

    ?&lt;style&gt;

Reading UTF-8 - BOM marker

I gather that you cannot bind a Java generics type parameter to a lower bound (i.e. using the `super` keyword).  I was reading what the [Angelika Langer Generics FAQ had to say on the subject][1].  They say it basically comes down to a lower bound being useless (&quot;not making any sense&quot;).

I&#39;m not convinced.  I can imagine a use for them to help you be more flexible to callers of a library method that produces a typed result.  Imagine a method that created an array list of a user-specified size and filled it with the empty string.  A simple declaration would be

    public static ArrayList&lt;String&gt; createArrayListFullOfEmptyStrings(int i);

But that&#39;s unnecessarily restrictive to your clients.  Why can&#39;t they invoke your method like this:

    //should compile
    List&lt;Object&gt; l1 = createArrayListFullOfEmptyStrings(5); 
    List&lt;CharSequence&gt; l2 = createArrayListFullOfEmptyStrings(5);
    List&lt;String&gt; l3 = createArrayListFullOfEmptyStrings(5);

    //shouldn&#39;t compile
    List&lt;Integer&gt; l4 = createArrayListFullOfEmptyStrings(5);

At this point I would be tempted to try the following definition:

    public static &lt;T super String&gt; List&lt;T&gt; createArrayListFullOfEmptyStrings(int size) {
      List&lt;T&gt; list = new ArrayList&lt;T&gt;(size);
      for(int i = 0; i &lt; size; i++) {
         list.add(&quot;&quot;);
      }
      return list;
    }

But it will not compile; the `super` keyword is illegal in this context.

**Is my example above a bad example (ignoring what I say below)?  Why isn&#39;t a lower bound useful here?  And if it would be useful, what&#39;s the real reason that it is not permitted in Java?**

P.S.
-
I know that a better organization *might* be something like this:

    public static void populateListWithEmptyStrings(List&lt;? super String&gt; list, int size);

    List&lt;CharSequence&gt; list = new ArrayList&lt;CharSequence&gt;();
    populateListWithEmptyStrings(list, 5);

Can we for the purpose of this question pretend that due to a requirement, we need to do both operations in one method call?

Edit
---
@Tom G (justifiably) asks what benefit having a `List&lt;CharSequence&gt;` would have over a `List&lt;String&gt;`.  For one, nobody said the returned list is immutable, so here&#39;s one advantage:

    List&lt;CharSequence&gt; l2 = createArrayListFullOfEmptyStrings(5);
    l2.add(new StringBuilder(&quot;foo&quot;).append(&quot;bar&quot;));

  [1]: http://www.angelikalanger.com/GenericsFAQ/FAQSections/TypeParameters.html#FAQ107

Why can&#39;t a Generic Type Parameter have a lower bound in Java?

So sometimes I want to include only one class from a namespace rather than a whole namespace, like the example here I create a alias to that class with the using statement:

    using System;
    using System.Text;
    using Array = System.Collections.ArrayList;

I often do this with generics so that I don&#39;t have to repeat the arguments:

    using LookupDictionary = System.Collections.Generic.Dictionary&lt;string, int&gt;;

Now I want to accomplish the same with a generic type, while preserving it as a generic type:

    using List&lt;T&gt; = System.Collections.Generic.List&lt;T&gt;;

But that doesn&#39;t compile, so is there any way to achieve creating this alias while leaving the type as generic?

Using a &#39;using alias = class&#39; with generic types?

What is the difference between `IEnumerable` and `IEnumerable&lt;T&gt;`? 

I&#39;ve seen many framework classes implementing both these interfaces, therefore I would like to know what advantages one get by implementing both?

Please have a look how they&#39;ve been defined:

    public interface IEnumerable
    {
        [DispId(-4)]
        IEnumerator GetEnumerator();
    }
    public interface IEnumerable&lt;T&gt; : IEnumerable
    {
        IEnumerator&lt;T&gt; GetEnumerator();
    }
 
As we see, `IEnumerable&lt;T&gt;` derives from `IEnumerable`, that means whatever `IEnumerable` has, `IEnumerable&lt;T&gt;` inherits, then why do we implement both instead of just `IEnumerable&lt;T&gt;`? Is implementing `IEnumerable&lt;T&gt;` not enough?

Likewise, there are other similar pairs:

  - `IList` and `IList&lt;T&gt;`  
  - `ICollection` and `ICollection&lt;T&gt;`

I would like to know about these as well.

Difference between IEnumerable and IEnumerable&lt;T&gt;?

Something called the &quot;bridge method&quot; concept related to Java Generics made me stop at a point and think over it.   

&gt; Btw, I only know that it occurs at the
&gt; bytecode level and is not available
&gt; for us to use.

  
But I am eager to know the concept behind the &quot;bridge method&quot; used by the Java compiler.  

What exactly happens behind the scenes and why it is used? 

Any help with an example would be greatly appreciated.  



Java Generics - Bridge method?

I have a string:

    var names = &quot;Brian,Joe,Chris&quot;;

Is there a way to convert this to a `List&lt;string&gt;` delimited by `,` in one line?

Convert string to List&lt;string&gt; in one line?

Under the target folder in IntelliJ for a Java project I created, I have a few java source files in the package.  Beside each file the &#39;J&#39; icon has a red circle with a line through it.

What does that mean?  How do I fix it?


What does this symbol mean in IntelliJ? (red circle on bottom-left corner of file name, with &#39;J&#39; in it)

I would like to search across projects for variable usages, or at least for strings.  I&#39;ve got [IndexYourFiles][1] which works well for text searches, but I have to re-index every now and then and would like an integrated solution.  

Is there any way that I can search across projects in IntelliJ IDEA? So far I have only been able to search within the currently-open project.  I&#39;m guessing IntelliJ can&#39;t do this natively; are there any plug-ins out there to support this?

Thanks.

  [1]: http://www.indexyourfiles.com/

IntelliJ IDEA global search

I have been using Eclipse for Android development and don&#39;t have a problem with it (I also use it for Web Service and C++ development under Linux) but I want to give IntelliJ IDEA a go as it appears to have favourable reviews.  This is easily possibly now that IDEA 10 has been released with Android support enabled in the Community Edition.

I have looked at IDEA and it looks pretty good to me with the only downside being the lack of UI on .xml file editing (AndroidManifest.xml for example) and the user interface builder provided with ADT 9.0.

Has anyone got experience they can share on IntelliJ IDEA and Android development?

EDIT:  Thanks all; I&#39;m sticking with Eclipse as I know it pretty well and it allows me to do pretty much anything (Java-related) I like for free.  I shouldn&#39;t look a gift horse in the mouth!


Benefits of switching from Eclipse to IntelliJ IDEA for Android development

With:

    Object method(){
        ...
        return /* some complex expression */
    }

Is there a way I can see what value will be returned while debugging? Like somehow set a breakpoint that would be hit right after the return, but before execution goes to the calling code?  I&#39;d like to be able to know what the return value is and also be able to see what values of all of the local variables are.

The way I do it now is by making a temporary variable: `Object ret = /* something complex */; return ret;`. But thats a hassle and also adds an extra unnecessary line of code.


Note: This is the same question as https://stackoverflow.com/questions/268048/can-i-find-out-the-return-value-before-returning-while-debugging-in-visual-studio, but for intellij.

Can I find out the return value before returning while debugging in Intellij?

Is there some shortcut that would allow me after creating method in an interface, select and jump to implementing class of that interface?

IntelliJ IDEA jump from interface to implementing class in Java

Other than the obvious fact that the first form could use a variable and not just a string literal, is there any reason to use one over the other, and if so under which cases?

In code:

    // Given:
    var foo = {&#39;bar&#39;: &#39;baz&#39;};

    // Then
    var x = foo[&#39;bar&#39;];

    // vs. 
    var x = foo.bar;

Context: I&#39;ve written a code generator which produces these expressions and I&#39;m wondering which is preferable.

JavaScript property access: dot notation vs. brackets?

I find it more convenient to access dict keys as `obj.foo` instead of `obj[&#39;foo&#39;]`, so I wrote this snippet:

    class AttributeDict(dict):
        def __getattr__(self, attr):
            return self[attr]
        def __setattr__(self, attr, value):
            self[attr] = value

However, I assume that there must be some reason that Python doesn&#39;t provide this functionality out of the box. What would be the caveats and pitfalls of accessing dict keys in this manner?

Accessing dict keys like an attribute?

I recently had to type in a small C test program and, in the process, I made a spelling mistake in the main function by accidentally using `vooid` instead of `void`.

And yet it still worked.

Reducing it down to its smallest complete version, I ended up with:

    int main (vooid) {
        return 42;
    }

This does _indeed_ compile (`gcc -Wall -o myprog myprog.c`) and, when run, it returns 42.

How exactly is this valid code?

---

Here&#39;s a transcript cut and pasted from my `bash` shell to show what I&#39;m doing:

    pax$ cat qq.c
    int main (vooid) {
        return 42;
    }
    
    pax$ rm qq ; gcc -Wall -o qq qq.c ; ./qq
    
    pax$ echo $?
    42


&quot;int main (vooid)&quot;? How does that work?

If I have a function which accepts more than one string parameter, the first parameter seems to get all the data assigned to it, and remaining parameters are passed in as empty.

A quick test script:

    Function Test([string]$arg1, [string]$arg2)
    {
        Write-Host &quot;`$arg1 value: $arg1&quot;
        Write-Host &quot;`$arg2 value: $arg2&quot;
    }
    
    Test(&quot;ABC&quot;, &quot;DEF&quot;)

The output generated is 

    $arg1 value: ABC DEF
    $arg2 value: 

The correct output should be:

    $arg1 value: ABC
    $arg2 value: DEF


This seems to be consistent between v1 and v2 on multiple machines, so obviously, I&#39;m doing something wrong. Can anyone point out exactly what?

How do I pass multiple parameters into a function in PowerShell?

In MediaWiki (wikipedia&#39;s) wiki syntax, is there a way to have a numbered list with a code block in the middle?

For example:

&lt;pre&gt;
# Number 1
# Number 2
  Indented section that will become a code block
# Number 3
# Number 4
&lt;/pre&gt;

What happens in MediaWiki is you end up with something like this:
&lt;pre&gt;
1. Number 1
2. Number 2
   Indented section that will become a code block
1. Number 3
2. Number 4
&lt;/pre&gt;

(Note how &quot;Number 3&quot; and &quot;Number 4&quot; are reset as 1 and 2... It looks like StackOverflow is much smarter than MediaWiki, i had to put my example in PRE tags to make it screw up!)

I know you can *indent* text using &quot;#:&quot; syntax...

&lt;pre&gt;
# Number 1
# Number 2
#: Indented section that will merely be indented
# Number 3
# Number 4
&lt;/pre&gt;


...but I really would like to get the same visual CSS class for my code even if it&#39;s in a numbered list.

It gets even more entertaining with nested lists. This syntax...


&lt;pre&gt;
# MainEntry 1
## Number 1
## Number 2
# MainEntry 2
## Number 1
## Number 2
  Indented section that will become a code block
## Number 3
## Number 4
&lt;/pre&gt;

...becomes...

&lt;pre&gt;
1. MainEntry 1
   1. Number 1
   2. Number 2
2. MainEntry 2
   1. Number 1
   2. Number 2
      Indented section that will become a code block
1. 1. Number 3
   2. Number 4
&lt;/pre&gt;

(Note how &quot;Number 3&quot; is now &quot;1. 1.&quot;)

Code block in numbered list (Wiki syntax)

I&#39;m trying to get my head around the use of the tilde operator, and associated functions.  My 1st question is why does `I()` need to be used to specify arithmetic operators? For example, these 2 plots generate different results (the former having a straight line, and the latter the expected curve)

    x &lt;- c(1:100)
    y &lt;- seq(0.1,10,0.1)
    
    plot(y~x^3)
    plot(y~I(x^3))

further, both of the following plots also generate the expected result

    plot(x^3, y)
    plot(I(x^3), y)

My second question is, perhaps the examples I&#39;ve been using are too simple, but I don&#39;t understand where `~` should actually be used.

In R formulas, why do I have to use the I() function on power terms, like y ~ I(x^3)

I want to know what does (~) mean in css. 

    #img1:hover ~ #img2 {
        opacity: 0;
    }

In visual studio, i get &#39;unexpected character sequence&#39; error when i use this symbol. what is the actual meaning of this in CSS. what does it do?



What does symbol tilde (~) mean in CSS

In Python console:

    ~True

Gives me:

    -2

Why? Can someone explain this particular case to me in binary?



Content Type	Original Author	Original Content on Stackoverflow
Question	Michael K	View Question on Stackoverflow
Solution 1 - Java	openCage	View Answer on Stackoverflow
Solution 2 - Java	Andreas Dolk	View Answer on Stackoverflow
Solution 3 - Java	RomanKousta	View Answer on Stackoverflow
Solution 4 - Java	Andrew White	View Answer on Stackoverflow

What does a tilde in angle brackets mean when creating a Java generic class?

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How to make an array of arrays in Java

Make a phone call programmatically

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