Pushing an element into an array type in MongoDB collection using Java Driver is not so obvious at the first attempt. I would share a sample program today that create a MongoDB connection and insert an element into an array type within a collection. We are going to connect to a MongoD server installed in […]
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Java Management Extension provides a powerful APIs to find out all details about the JVM. Today we will write a simple program to find out dead lock in java using JMX API. The intention of this program is only to find the dead lock, the program which is used to create the dead lock should […]
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Java JMX API provides you some useful classes to find out details about your JVM. One of those classes is ManagementFactory, This class provides API to find meta data about the JVM. In the below given example we will find all the live threads in the JVM and its state.
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package com.ourownjava.corejava.thread; import java.lang.management.ManagementFactory; import java.lang.management.ThreadInfo; /** * @author ourownjava.com * @date 28th June, 2011 * * Example program to find all live threads in your JVM instance. * */ public class ManagementFactoryExample { public static void main(final String args[]){ final WorkerThread worker = new WorkerThread(); worker.setName("workerThread"); worker.start(); final ThreadInfo[] threadInfos = ManagementFactory.getThreadMXBean(). getThreadInfo(ManagementFactory.getThreadMXBean().getAllThreadIds()); for(final ThreadInfo threadInfo : threadInfos){ System.out.println(threadInfo.getThreadId()); System.out.println(threadInfo.getThreadName()); System.out.println(threadInfo.getThreadState()); } System.out.println("Total number of live threads :"+ManagementFactory.getThreadMXBean().getThreadCount()); } } class WorkerThread extends Thread{ public void run(){ try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } } } |
Console output.
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/mnt/opt/java com.ourownjava.corejava.thread.ManagementFactoryExample 8 workerThread TIMED_WAITING 5 Attach Listener RUNNABLE 4 Signal Dispatcher RUNNABLE 3 Finalizer WAITING 2 Reference Handler WAITING 1 main RUNNABLE Total number of live threads :6 |
Java util package provides us number of sorted data structures; one of those is the TreeSet. TreeSet is an implementation of Set and it stores the elements in sorted order. All elements needs to be added into a TreeSet should implement Comparable interface directly or indirectly or the TreeSet should be constructed with an appropriate […]
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When multiple threads work on a shared resource its quiet possible that one thread’s work is over written by another one if the shared resource is modified without a mutually exclusive lock. This can be solved by moving the code responsible for the state change of the shared resource into a synchronized method/block. What if […]
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There is a tool called javap to find out the compiler version and much more from a class file. See the below given console output to get more details. javap is located in %JAVA_HOME%/bin.
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opt/mnt/javap -verbose JNDIClientExample Compiled from "JNDIClientExample.java" public class org.sanju.JNDIClientExample extends java.lang.Object SourceFile: "JNDIClientExample.java" minor version: 0 major version: 50 Constant pool: const #1 = class #2; // org/sanju/JNDIClientExample const #2 = Asciz org/sanju/JNDIClientExample; const #3 = class #4; // java/lang/Object const #4 = Asciz java/lang/Object; Below given details will help you to map a major version into JDK version. 1.1 (major version: 45 minor: 3) 1.2 (major version: 46 minor: 0) 1.3 (major version: 47 minor: 0) 1.4 (major version: 48 minor: 0) 1.5, 5 or 5.0 (major version: 49 minor: 0) 1.6, 6 or 6.0 (major version: 50 minor: 0) |
If you want to list out all files from a given directory or drive you can use the list method in the java.io.File class. Consider a scenario where you wanted to list out all files with specific extension. FileFilter interface will help you to filter files using any criteria you can imagine. Today we will […]
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You might want to take the Thread dump of JVM instance to check the state of your threads if its stop responding. In linux you can use “kill -QUIT process_id” of the JVM instance to get the thred dump. Thread dump can give you details like state of all threds in the JVM and the […]
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Below given program will list out all root level dimensions in an Endeca index. (dgraph) This program will be useful if you don’t have access to Endeca jsp reference application or reference application is not coming up due to some reason. This program connect to MDEX installed in localhost and running in port 15000. You […]
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Unlike many other languages it is simple to create and manage threads in java. Your class can gain the concurrent behavior through either extending java.lang.Thread class or implementing java.lang.Runnable interface. Thread class itself implements Runnable interface, due to the same reason compiler will not force the programmer to give an implementation of run() method if […]
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