Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I agree with @Joachim. </p> <h2>The below suggestion was a myth</h2> <p><em>In addition, it is recommended (in good coding convention) that <strong>do not declare any object inside the loop</strong>. Instead, declare it just before the loop start and use the same reference for initialization purpose. This will ask your code to use the same reference for each iterations and cause less burden on memory release thread (i.e. Garbage collection).</em> </p> <p><strong>The Truth</strong><br> I have <strong>edited</strong> this because I feel that there may be many people who (like me before today) still believe that declaring an object inside loop could harm the memory management; which is wrong.<br> To demonstrate this, I have used the same code posted on <a href="https://stackoverflow.com/questions/25552/using-java-to-get-os-level-system-information">stackOverflow for this</a>.<br> Following is my code snippet</p> <pre><code>package navsoft.advskill.test; import java.util.ArrayList; public class MemoryTest { /** * @param args */ public static void main(String[] args) { /* Total number of processors or cores available to the JVM */ System.out.println("Available processors (cores): " + Runtime.getRuntime().availableProcessors()); /* * Total amount of free memory available to the JVM */ long freeMemory = Runtime.getRuntime().freeMemory(); System.out.println("Free memory (bytes): " + freeMemory); /* * This will return Long.MAX_VALUE if there is no preset limit */ long maxMemory = Runtime.getRuntime().maxMemory(); /* * Maximum amount of memory the JVM will attempt to use */ System.out.println("Maximum memory (bytes): " + (maxMemory == Long.MAX_VALUE ? "no limit" : maxMemory)); /* * Total memory currently in use by the JVM */ System.out.println("Total memory (bytes): " + Runtime.getRuntime().totalMemory()); final int LIMIT_COUNTER = 1000000; //System.out.println("Testing Only for print..."); System.out.println("Testing for Collection inside Loop..."); //System.out.println("Testing for Collection outside Loop..."); //ArrayList&lt;String&gt; arr; for (int i = 0; i &lt; LIMIT_COUNTER; ++i) { //arr = new ArrayList&lt;String&gt;(); ArrayList&lt;String&gt; arr = new ArrayList&lt;String&gt;(); System.out.println("" + i + ". Occupied(OldFree - currentFree): "+ (freeMemory - Runtime.getRuntime().freeMemory())); } System.out.println("Occupied At the End: "+ (freeMemory - Runtime.getRuntime().freeMemory())); System.out.println("End of Test"); } } </code></pre> <p>The result from the output is clearly shows that there is no difference in occupying/freeing the memory if you either declare the object inside or outside the loop. So it is recommended to have the declaration to as small scope as it can.<br> I pay my thanks to all the experts on StackOverflow (specially @Miserable Variable) for guiding me on this. </p> <p>Hope this would clear your doubts too.</p>
    singulars
    1. This table or related slice is empty.
    1. POJava out of heap space during serialization
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USNaved
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI'm not convinced that this will have any effect at all. In fact I *highly* suspect the compiler to re-use the same local variable slot for `arrayList` in each loop iteration, which would make it equivalent to "declare it outside the loop".
      singulars
      1. PO
      1. USJoachim Sauer
    2. CO-1 What? Recommendation is to *always* declare variable with smallest scope. Can you site any references?
      singulars
      1. PO
      1. USMiserable Variable
    3. CO@HemalPandya, While creating a coding convention for my current organization, I referred this http://weblogs.java.net/blog/ddevore/archive/2006/08/declare_variabl.html
      singulars
      1. PO
      1. USNaved
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload