Press &lt;kbd&gt;Alt&lt;/kbd&gt;+&lt;kbd&gt;Left Arrow&lt;/kbd&gt; and &lt;kbd&gt;Alt&lt;/kbd&gt;+&lt;kbd&gt;Right Arrow&lt;/kbd&gt; like you would in a web browser.

On OS X: 

  * &lt;kbd&gt;⌘&lt;/kbd&gt; + &lt;kbd&gt;[&lt;/kbd&gt; ( Command + [ ) : Go Back 
  * &lt;kbd&gt;⌘&lt;/kbd&gt; + &lt;kbd&gt;]&lt;/kbd&gt; ( Command + ] ) : Go Forward

As Robin mentioned, you can also jump to the last edit location. Ctrl+Q is the keyboard shortcut for this!

On Windows/Ubuntu this was always 

`ALT+LEFT ARROW = Go back` 

`ALT+RIGHT ARROW = Go forward` 

*However, on MAC OSX*, for me it was 

`ALT(Option)+COMMAND+LEFT ARROW = Go back` 

`ALT(Option)+COMMAND+RIGHT ARROW = Go forward` 

Hopefully this will help other Mac people in the future who banged their head on the desk when the other answers did not work.

In addition to the keyboard shortcut mentioned by @lucas, there is the left and right arrow icons in the toolbar.  It also has a handy back to last edit location as well.  

Both of these are of course reflected in the menu under Navigate as well.

Keyboard bindings can change based on your OS and current Keys Scheme. So the best way to know a keyboard binding is to look up its Command in Preferences &gt; Keys. That is also where you can change or add a keyboard binding.

Which means instead of asking for a shortcut, you should generally ask for the command (or at least ask for both). In this case the commands you want are `Backward History` and `Forward History`. You can see in the following screenshot that they are mapped to &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;[&lt;/kbd&gt; and &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;]&lt;/kbd&gt; in my Key Scheme (because I changed them to that). 

[![enter image description here][1]][1]

As mentioned by others, `Last Edit Location` can be a really useful command also. In my case it&#39;s mapped to &lt;kbd&gt;Ctrl&lt;/kbd&gt;+&lt;kbd&gt;Q&lt;/kbd&gt;, but you check it under Keys :).


  [1]: https://i.stack.imgur.com/XRsvt.png

These commands are very frequently used, so it is worth having all their shortcuts the same way in all your IDEs. To adjust them:

 1. Open Eclipse
 2. Windows -&gt; Preferences -&gt; General -&gt; Keys
 2. Search for &quot;Backward History&quot; and &quot;Forward History&quot; and adjust the bindings.

For me personally Visual Studio&#39;s default Ctrl+- and Ctrl+= works best.



I am trying to display milliseconds in an Excel macro.  I have a column of integers which are timestamps in milliseconds (e.g. 28095200 is 7:48:15.200 am), and I want to make a new column next to it which keeps a running average and displays the time in a &lt;code&gt;hh:mm:ss.000&lt;/code&gt; format.  

     Dim Cel As Range
     Set Cel = Range(&quot;B1&quot;)
     temp = Application.Average(Range(&quot;A1:A2&quot;)) / 1000
     ms = Round(temp - Int(temp), 2) * 1000
     Cel.Value = Strings.Format((temp / 60 / 60 / 24), &quot;hh:mm:ss&quot;) _
                    &amp; &quot;.&quot; &amp; Strings.Format(ms, &quot;#000&quot;)

This only displays &quot;mm:ss.0&quot; in the cell.  Yet when I click on the cell, it shows &quot;hh:mm:ss&quot; in the formula bar.  Why are the hours missing? How can I show the hours, minutes, seconds, and milliseconds?

Display milliseconds in Excel

The code for the myAny function in &lt;a href=&quot;https://stackoverflow.com/questions/833186/why-does-this-haskell-code-work-successfully-with-infinite-lists/833218&quot;&gt;this question&lt;/a&gt; uses foldr.  It stops processing an infinite list when the predicate is satisfied.

I rewrote it using foldl:

&lt;pre&gt;&lt;code&gt;myAny :: (a -&gt; Bool) -&gt; [a] -&gt; Bool
myAny p list = foldl step False list
   where
      step acc item = p item || acc&lt;/code&gt;&lt;/pre&gt;

(Note that the arguments to the step function are correctly reversed.)

However, it no longer stops processing infinite lists.

I attempted to trace the function&#39;s execution as in &lt;a href=&quot;https://stackoverflow.com/questions/833186/why-does-this-haskell-code-work-successfully-with-infinite-lists/833218#833218&quot;&gt;Apocalisp&#39;s answer&lt;/a&gt;:

&lt;pre&gt;&lt;code&gt;myAny even [1..]
foldl step False [1..]
step (foldl step False [2..]) 1
even 1 || (foldl step False [2..])
False  || (foldl step False [2..])
foldl step False [2..]
step (foldl step False [3..]) 2
even 2 || (foldl step False [3..])
True   || (foldl step False [3..])
True&lt;/code&gt;&lt;/pre&gt;

However, this is not the way the function behaves.  How is this wrong?

foldl versus foldr behavior with infinite lists

Is there a way to go back in Eclipse? Basically, when I&#39;m jumping around a big project following the execution flow (ctrl + click and etc.), is there a way to retrace a step? If my code calls a method and I go to the method definition, is there a key combination that will take me back to the calling code?

How to go back in Eclipse?

<p>Is there a way to go back in Eclipse? Basically, when I'm jumping around a big project following the execution flow (ctrl + click and etc.), is there a way to retrace a step? If my code calls a method and I go to the method definition, is there a key combination that will take me back to the calling code?</p>


I&#39;m creating a little Java application which should have a progress indicator with percentages. In every loop it uses backspace `\b` to remove the displayed progress before displaying the next percentage.

Here&#39;s a simplified example:

    public static void main(String[] args) throws Exception {
        System.out.print(&quot;Progress: &quot;);
        for (int percentage = 0; percentage &lt; 100; percentage++) {
            System.out.print(percentage + &quot;%&quot;);
            Thread.sleep(10); // Stub for &quot;long running task&quot;.
            int length = String.valueOf(percentage).length() + 1;
            while (length-- &gt; 0) {
                System.out.print(&#39;\b&#39;);
            }
        }
        System.out.println(&quot;finished!&quot;);
    }

This works perfectly in command prompt, but the backspace character isn&#39;t recognized in Eclipse&#39;s console (Galileo build 20090920-1017). It instead displays an empty square denoting an unknown character. See screenshot:

![alt text][1]

How do I get Eclipse to &quot;display&quot; the backspace properly? I.e. let it remove the previous character.

This is actually no showstopper since it will just be run in command console, but it would be just nice to get it to work in Eclipse as well :)

  [1]: https://i.stack.imgur.com/InTzR.png

How to get backspace \b to work in Eclipse&#39;s console?

Using JUnit 4.8 and the new `@Category` annotations, is there a way to choose a subset of categories to run with Maven&#39;s Surefire plugin?

For example I have:

    @Test
    public void a() {
    }

    @Category(SlowTests.class)
    @Test
    public void b() {
    }

And I&#39;d like to run all non-slow tests as in: (note that the -Dtest.categories was made up by me...).

    mvn test -Dtest.categories=!SlowTests // run non-slow tests
    mvn test -Dtest.categories=SlowTests // run only slow tests
    mvn test -Dtest.categories=SlowTests,FastTests // run only slow tests and fast tests
    mvn test // run all tests, including non-categorized

So the point is that I don&#39;t want to have to create test suites (Maven just picks up all unit tests in the project which is very convenient) and I&#39;d like Maven to be able to pick the tests by category.
I think I just made up the -Dtest.categories, so I was wondering if there&#39;s a similar facility I can use?

How to run JUnit tests by category in Maven?

I&#39;m  getting this error while building Maven project, I increased MAVEN_OPTS but all the same, I found some similar posts but they are refering to something else. How do I fix this?

    The system is out of resources.
    Consult the following stack trace for details.
    java.lang.OutOfMemoryError: PermGen space
            at java.lang.ClassLoader.defineClass1(Native Method)
            at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
            at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
            at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
            at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
            at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
            at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
            at java.security.AccessController.doPrivileged(Native Method)
            at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
            at org.codehaus.plexus.compiler.javac.IsolatedClassLoader.loadClass(IsolatedClassLoader.java:56)
            at com.sun.tools.javac.comp.Annotate.&lt;init&gt;(Annotate.java:52)
            at com.sun.tools.javac.comp.Annotate.instance(Annotate.java:36)
            at com.sun.tools.javac.jvm.ClassReader.&lt;init&gt;(ClassReader.java:215)
            at com.sun.tools.javac.jvm.ClassReader.instance(ClassReader.java:168)
            at com.sun.tools.javac.main.JavaCompiler.&lt;init&gt;(JavaCompiler.java:293)
            at com.sun.tools.javac.main.JavaCompiler.instance(JavaCompiler.java:72)
            at com.sun.tools.javac.main.Main.compile(Main.java:340)
            at com.sun.tools.javac.main.Main.compile(Main.java:279)
            at com.sun.tools.javac.main.Main.compile(Main.java:270)
            at com.sun.tools.javac.Main.compile(Main.java:87)
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
            at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
            at java.lang.reflect.Method.invoke(Method.java:597)
            at org.codehaus.plexus.compiler.javac.JavacCompiler.compileInProcess(JavacCompiler.java:420)
            at org.codehaus.plexus.compiler.javac.JavacCompiler.compile(JavacCompiler.java:141)
            at org.apache.maven.plugin.AbstractCompilerMojo.execute(AbstractCompilerMojo.java:493)
            at org.apache.maven.plugin.CompilerMojo.execute(CompilerMojo.java:114)
            at org.apache.maven.plugin.DefaultPluginManager.executeMojo(DefaultPluginManager.java:490)
            at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
            at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556)
            at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535)

I&#39;m not as worried about how to fix as to how to fix it *in the maven ecosystem*

&quot;java.lang.OutOfMemoryError: PermGen space&quot; in Maven build

By looking around here as well as the internet in general, I have found [Bouncy Castle][1]. I want to use Bouncy Castle (or some other freely available utility) to generate a SHA-256 Hash of a String in Java. Looking at their documentation I can&#39;t seem to find any good examples of what I want to do. Can anybody here help me out?


  [1]: http://www.bouncycastle.org

Hash String via SHA-256 in Java

I run into this case a lot of times when doing simple text processing and print statements where I am looping over a collection and I want to special case the last element (for example every normal element will be comma separated except for the last case).

Is there some best practice idiom or elegant form that doesn&#39;t require duplicating code or shoving in an if, else in the loop.

For example I have a list of strings that I want to print in a comma separated list. (the do while solution already assumes the list has 2 or more elements otherwise it&#39;d be just as bad as the more correct for loop with conditional).

e.g. List&lt;String&gt; = (&quot;dog&quot;, &quot;cat&quot;, &quot;bat&quot;)

I want to print &quot;[dog, cat, bat]&quot;

I present 2 methods the

 1. For loop with conditional



        public static String forLoopConditional(String[] items) {

        String itemOutput = &quot;[&quot;;
    
        for (int i = 0; i &lt; items.length; i++) {
            // Check if we&#39;re not at the last element
            if (i &lt; (items.length - 1)) {
                itemOutput += items[i] + &quot;, &quot;;
            } else {
                // last element
                itemOutput += items[i];
            }
        }
        itemOutput += &quot;]&quot;;
    
        return itemOutput;
         }


 2. do while loop priming the loop


        public static String doWhileLoopPrime(String[] items) {
        String itemOutput = &quot;[&quot;;
        int i = 0;

        itemOutput += items[i++];
        if (i &lt; (items.length)) {
            do {
                itemOutput += &quot;, &quot; + items[i++];
            } while (i &lt; items.length);
        }
        itemOutput += &quot;]&quot;;

        return itemOutput;
        }
Tester class:

    
        public static void main(String[] args) {
            String[] items = { &quot;dog&quot;, &quot;cat&quot;, &quot;bat&quot; };
    
            System.out.println(forLoopConditional(items));
            System.out.println(doWhileLoopPrime(items));
    
        }

In the Java AbstractCollection class it has the following implementation (a little verbose because it contains all edge case error checking, but not bad).

    public String toString() {
        Iterator&lt;E&gt; i = iterator();
	if (! i.hasNext())
	    return &quot;[]&quot;;

	StringBuilder sb = new StringBuilder();
	sb.append(&#39;[&#39;);
	for (;;) {
	    E e = i.next();
	    sb.append(e == this ? &quot;(this Collection)&quot; : e);
	    if (! i.hasNext())
		return sb.append(&#39;]&#39;).toString();
	    sb.append(&quot;, &quot;);
	}
    }


Best Loop Idiom for special casing the last element

How can I configure the font size for the tree item in the package explorer/outline in Eclipse?

Which item in Font under *Preferences* I should change?



How can I configure the font size for the tree item in the package explorer in Eclipse?

I am using eclipse on my project and while messing around with my eclipse settings, I turned on Javascript support. Now eclipse complains that JQuery library has errors in it and is not letting me compile the project. Does anyone know how to turn javascript validation off? 


How do I remove javascript validation from my eclipse project?

I create a Maven project in Eclipse Helios. It works fine for a day, but then this warning shows up:

&gt;Build path specifies execution environment J2SE-1.4. There are no JREs installed in the workspace that are strictly compatible with this environment. 

Since this message, the project stopped compiling and debugging. Does anyone have solution for this problem?

Warning - Build path specifies execution environment J2SE-1.4

I&#39;m spending a lot of time manually expanding deeply-nested folders in tree views like the Project Explorer and the File Search result tree. Is there a keyboard shortcut or menu command to expand all folders? 

Content Type	Original Author	Original Content on Stackoverflow
Question	froadie	View Question on Stackoverflow
Solution 1 - Java	lucas	View Answer on Stackoverflow
Solution 2 - Java	vaichidrewar	View Answer on Stackoverflow
Solution 3 - Java	EMurnane	View Answer on Stackoverflow
Solution 4 - Java	stevebot	View Answer on Stackoverflow
Solution 5 - Java	Robin	View Answer on Stackoverflow
Solution 6 - Java	studgeek	View Answer on Stackoverflow
Solution 7 - Java	chris544	View Answer on Stackoverflow

How to go back in Eclipse?

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foldl versus foldr behavior with infinite lists

Display milliseconds in Excel

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