If you want to just redirect STDERR to tee, run the following command.
some-command 2> >(tee /var/tmp/output)Category: Programming
Mocking Static Methods That Return void in Java
This is one of those things that I tend to do on a regular basis . . . but unfortunately don’t remember the details each time, so I am adding it for future reference.
Often, developers will want to mock static methods that return void. The Mockito and PowerMockito frameworks provide for this, but the syntax isn’t immediately obvious.
Following is an example.
public class SomeClass {
public static void doSomething(String arg1, int arg2) {
// Method that does something...
Solution for Executing Native Process from Java that Requires sudo
If you are building a Java program that requires the ability to execute native commands on the machine which require sudo it requires some additional considerations other than just writing the Java code.
The problem is that sudo, by default, requires a tty for executing sudo such that a password can entered. Even if you configure sudoers to grant NOPASSWD access to a specific command you will still get the following error
sudo: sorry, you must have a tty to Dynamically Instantiating Classes in Python
A common design pattern is to define a class or list of classeses in configuration such that at runtime the classes can be dynamically instantiated.
I’ve done this before in many other languages and had need to do so today in Python (2.7.11)
It seems as though the clean way to do so is by using the Pyton importlib module. By using it, it enables you to cleanly dynamically import sub modules
Following is an example:
import importlib
klass_1_module = Java PowerMock Could not reconfigure JMX java.lang.LinkageError Solution
If you are using Mockito and PowerMock to build mocks for your Java tests and you run into the following error:
2016-05-05 17:31:20,204 main ERROR Could not reconfigure JMX java.lang.LinkageError: loader constraint violation: loader (instance of org/powermock/core/classloader/MockClassLoader) previously initiated loading for a different type with name "javax/management/MBeanServer"
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:760)
at org.powermock.core.classloader.MockClassLoader.loadUnmockedClass(MockClassLoader.java:238)
at org.powermock.core.classloader.MockClassLoader.loadModifiedClass(MockClassLoader.java:182)
at org.powermock.core.classloader.DeferSupportingClassLoader.loadClass(DeferSupportingClassLoader.java:70)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)Simply add the following as a class level annotation:
@PowerMockIgnore( {"javax.management.*"} )→ Continue reading “Java PowerMock Could not reconfigure JMX java.lang.LinkageError Solution”
Looping Through a List of Files with Spaces in the File Name with Bash
If you have a list of files that you want to operate on in a loop in bash and some of them have spaces in the file name the default IFS (Internal Field Separator) will match with the space and tokenize the file.
The simple approach is to temporarily set the IFS as follows. This can be done in a shell script, but the following example is directly on the command line for ‘one-liner’ usage.
OIFS="$IFS"
IFS=$'\n'
for i in How To Remove the Byte Order Mark (BOM) from UTF-8 Encoded Text Files
The easiest way that I have seen so far for doing so is to use tail and simply read everything except the first three bytes (start reading at the 4th byte), as follows:
tail --bytes=+4 text_file.txt text_file-wo-bom.txt[SOLVED] java.lang.NoSuchMethodError: org.apache.avro.generic.GenericData.createDatumWriter When Using Avro Data with MapReduce
I am working on a project and have decided to use Avro for the data serialization format.
I encountered the following error when trying to set up the unit test to test the mapper implementation through Eclipse:
java.lang.NoSuchMethodError: org.apache.avro.generic.GenericData.createDatumWriter(Lorg/apache/avro/Schema;)Lorg/apache/avro/io/DatumWriter;
at org.apache.avro.hadoop.io.AvroSerialization.getSerializer(AvroSerialization.java:114)
at org.apache.hadoop.io.serializer.SerializationFactory.getSerializer(SerializationFactory.java:82)
at org.apache.hadoop.mrunit.internal.io.Serialization.copy(Serialization.java:67)
at org.apache.hadoop.mrunit.internal.io.Serialization.copy(Serialization.java:98)
at org.apache.hadoop.mrunit.internal.io.Serialization.copyWithConf(Serialization.java:111)
at org.apache.hadoop.mrunit.TestDriver.copy(TestDriver.java:676)
at org.apache.hadoop.mrunit.TestDriver.copyPair(TestDriver.java:680)
at org.apache.hadoop.mrunit.MapDriverBase.addInput(MapDriverBase.java:120)
at org.apache.hadoop.mrunit.MapDriverBase.addInput(MapDriverBase.java:130)
at org.apache.hadoop.mrunit.MapDriverBase.addAll(MapDriverBase.java:141)
at org.apache.hadoop.mrunit.MapDriverBase.withAll(MapDriverBase.java:247)
at com.ryanchapin.hadoop.mapreduce.mrunit.UserDataSortTest.testMapper(UserDataSortTest.java:111)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
Configuring Hidden, Invisible, or Whitespace Characters in The Eclipse Text Editor
The newer (I am currently using Mars, 4.5.0) versions of Eclipse provide very good tools for configuring the visibility of whitespace characters in code.
To customize your settings go to Window -> Preferences -> General -> Editors -> Text Editors.
On that page there will be checkbox option next to “Show whitespace characters (configure visibility).
Clicking on the ‘configure visibility’ link will allow you to choose what is shown and the opacity of the whitespace characters, which is a really → Continue reading “Configuring Hidden, Invisible, or Whitespace Characters in The Eclipse Text Editor”
Using the Eclipse Memory Analyzer (MAT) Remotely on Large Heap Dumps
Sometime your java applilcation will fail and generate an enormous heap dump. One that may be too large to be able to transfer to your local machine and to analyze for lack of RAM, time or both.
One solution is to install the MAT tool on the remote server and generate an HTML output of the analysis to download and view locally. This saves the headache of attempting to get X Windows installed on the remote machine and get all → Continue reading “Using the Eclipse Memory Analyzer (MAT) Remotely on Large Heap Dumps”