Databases
StackOverflow2013
Postsdbo
POJava: NoSuchMethodException when method clearly exists
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POJava: NoSuchMethodException when method clearly exists
    primarykey
    data
    text
    <p>On my current project, I've felt the need to create a sort of simulated callback system in Java using reflection. However, I'm having issues getting my reflection to actually function. The code at fault follows:</p> <pre><code>public Callback(Object parentObj, String methodName, Class&lt;?&gt;...parameters) { if(parentObj == null) throw new IllegalArgumentException("parentObj cannot be null", new NullPointerException()); Class&lt;?&gt; clazz = parentObj.getClass(); // Trace debugging, see output for(Method m : clazz.getDeclaredMethods()) if(m.getName().equals("myMethod")) System.out.println (m); try { this.method = clazz.getMethod(methodName, parameters); } catch(NoSuchMethodException nsme) { nsme.printStackTrace(); } // Exception caught catch(SecurityException se) { se.printStackTrace(); } this.parentObj = parentObj; this.parameters = parameters; } </code></pre> <p>When I construct the <code>Callback</code> object, I'm using syntax like this:</p> <pre><code>new Callback(this, "myMethod", boolean.class) </code></pre> <p>When I try to create my pseudo-callback, it hits the <code>NoSuchMethodException</code> catch block. I've included some trace debugging above to show the output of one of my methods failing. The output:</p> <pre><code>private void my.package.MyClass.myMethod(boolean) java.lang.NoSuchMethodException: my.package.MyClass.myMethod(boolean) at java.lang.Class.getMethod(Class.java:1605) at my.package.other.Callback.&lt;init&gt;(Callback.java:63) </code></pre> <p>I couldn't figure the problem out, so I started hunting, to little avail. The best I could find was mention of versioning conflict between the compiled JAR and the runtime. However, <code>MyJar.jar/META-INF/MANIFEST.MF</code> contains <code>Created-By: 1.6.0_02 (Sun Microsystems Inc.)</code>. My IDE is running <code>C:\Program Files\Java\jdk1.6.0_02\bin\javac.exe</code> to compile my project. I'm using <code>C:\Program Files\Java\jdk1.6.0_02\bin\java.exe</code> to run my JAR.</p> <p>I'm at a loss why <code>Class.getMethod</code> is claiming the method doesn't exist, but <code>Class.getMethods</code> seems to have no problem finding it. Help? :(</p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. This table or related slice is empty.
    1. USBrian S
    plurals
    1. This table or related slice is empty.
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTDuplicate
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThat's why you don't rely on Reflection, which is unreliable at best.
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. USquantumSoup
    2. COI wouldn't say it's unreliable, but it can be complicated and inefficient.
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. USAdam Crume
    3. COIt's certainly less reliable than something your compiler can prove is correct. :-)
      singulars
      1. POJava: NoSuchMethodException when method clearly exists
      1. USLaurence Gonsalves
 

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