Tomcat 7.0 failed with a SEVERE error without printing a stack trace: Dec 30, 2011 1:21:09 PM org.apache.catalina.core.S... Now it's hard to figure out what's wrong without knowing where things went wrong. Why is Tomcat not logging anything? Tomcat logging is configured by class loader. Logging behaves differently depending on which class loader loaded the logger. You'll need to look at both $CATALINA_BASE/conf/logging.properties and WEB-INF/classes/logging.properties to figure out why the stack trace is not logged. In my case, the web app specific WEB-INF/classes/logging.properties overshadowed the system $CATALINA_BASE/conf/logging.properties and suppressed the stack trace.

This is a series of notes on building custom JSF 2.0 facelet taglibs, ordered from the simplest to the less simple. Hopefully it can help you to get started on how to build custom taglibs for JSF. A simple JSF facelets taglib example The simplest taglib I can think of. Using EL expression with a custom tag Make tag attributes dynamic. Mixing custom tag with facelet ui taglibs Discover things you might run into when you get into more details. Which EL context to use? Using the wrong EL context can lead to subtle bugs. JSF facelet taglib backed by a UI component A UIComponent can be a tag handler, without being TagHandler . Using tag handler, UI component and renderer with a JSF facelet...

Experts may disagree but I found it absolutely stunning that JSF EL does not provide an operator for string concatenation. The Java "+" operator is there for the take. Java, which is a strongly typed compiled language, overloads the "+" operator in such a way that any object can be concatenated with a string. But JSF EL, which definitely isn't as strongly typed as Java, restricts the "+" operator to numerical values only! Of course, experts may argue that the "+" operator overloading is a huge design flaw of the Java language. But even so, JSF EL is not the right place to fix it! In some cases, a concatenation operator isn't needed, for example: <ui:repeat var="tab" value="#{tabs}"> <img ... But in case the concatenated...

The stack trace is like this: java.lang.IllegalArgumentException: Component prop... You get this error because you are using the class attribute with a JSF UI component, for which the class attribute cannot be altered. Of course you meant CSS class, not Java class! You can use the styleClass attribute instead of the class attribute. The styleClass attribute becomes the class attribute when the component is rendered. If you can add a tag handler to the UI component, you can alias class to styleClass , which will allow you to use the class attribute on the UI component: import javax.faces.view.facelets.*; pub...

I built a very basic JSF application and deployed to Tomcat 7.0.22, but it failed with this error: Caused by: java.lang.ClassFormatError: Absent Code... That looks weird and I wasn't able to find a sensible explanation! So I copied the jsf-api-2.1.jar , which was downloaded from the java.net Maven repository by Maven, into a temp folder. And tested it with this simple program: public class ClassFormatErrorTest { public ... I also copied servlet-api.jar from Tomcat's lib folder to the temp folder. Sure enough it failed with the same error: C:\tmp>java -cp .;jsf-api-2.1.jar;servlet-api.jar ... But when I replaced the javax.faces.webapp.FacesServlet class with one I compiled from source, the error disappears! Conclusions: The jar file jsf-api-2.1.jar from java.net Maven repository is good for compilation only (cannot be used...

Copied verbatim from The GNU C Library Manual . When you have finished using a socket, you can simply close its file descriptor with close ; see Opening and Closing Files . If there is still data waiting to be transmitted over the connection, normally close tries to complete this transmission. You can control this behavior using the SO_LINGER socket option to specify a timeout period; see Socket Options . You can also shut down only reception or transmission on a connection by calling shutdown , which is declared in sys/socket.h . Function: int shutdown (int socket, int how) The shutdown function shuts down the connection of socket socket. The argument how specifies what action to perform: 0 - Stop receiving data for this socket....

The Android unit test framework is based on JUnit 3 , not JUnit 4. Test cases have to extend junit.framework.TestCase or a subclass (such as android.test.InstrumentationTestCase ). Tests are identified by public methods whose name starts with test , not methods annotated with @Test (as in JUnit 4). An Android test suite is packaged as an APK, just like the application being tested. To create a test package, first you need to identify the application package it is testing. Google suggests to put the test package source in a directory named tests/ alongside the src/ directory of the main application. At runtime, Android instrumentation loads both the test package and the application under test into the same process. Therefore, the tests can invoke methods on...

Install APK with adb : $ platform-tools/adb install out/target/product/ge... Error message in logcat: D/PackageParser( 60): Scanning package: /data/ap... The error was created by android.content.pm.PackageParser , which compares the android:minSdkVersion and android:targetSdkVersion attributes of the uses-sdk element of AndroidManifest.xml in the APK file against the SDK version of the device or emulator. The SDK version on the device has to be greater than that required by android:minSdkVersion . In my case, since I built the package with AOSP, the target emulator has to be AOSP also. This is the relavant section in AndroidManifest.xml : <uses-sdk android:minSdkVersion="AOSP" ... And the relevant section in android.content.pm.PackageParser : if (minCode != null) { if (!minCode.equals(...

Got "base64: invalid input" error: $ base64 -d base64_encoded.txt >original.bin ba... which can be easily dismissed as "input is invalid base64 encoded" or "partial input". But I know it's valid base64 encoded input! The problem was, the input was base64 encoded on Windows! The error goes away after converting to Unix format with dos2unix . dos2unix < base64_encoded.txt | base64 -d >origina... Version of base64 used: $ base64 --version base64 (GNU coreutils) 8.5 ...

When I used AssetManager to open an XML file in a ContentProvider : getContext().getAssets().openFd("demo.xml"); it failed with this exception: java.io.FileNotFoundException: This file can not b... It turned out that openFd only works for asset files that are not compressed. It works on media files such as .mp3 , .jpg , .wmv etc., which are not compressed during packaging. XML files are compressed by dedault, causing openFd to fail. An Android ticket was opened on this issue. Till that is fixed, the workaround is to add an exclusion in build.xml : <?xml version="1.0" encoding="UTF-8"?> <pro...