Programming

Lambda Expressions in java – A Java 8 feature

What are Lambda Expression – Java 8 new feature?

Lambda expressions refers to what we had anonymous classes in the older versions of java.

So the very next straight forward thing comes to our mind, if already java is having anonymous classes why a replacement for the same is needed?

Why are Lambda Expressions needed, even if anonymous classes already exist?

The answer goes very simple, Lambda expressions when used makes our code more lighter as compared to when we use anonymous classes.

For Example:

Consider there is a class called Person
To sort the Person class by name if we use anonymous class we have to use the following code

Collections.sort(list, new Comparator() {
  @Override
  public int compare(Person p1, Person p2) {
       return p1.getName().compareTo(p2.getName());
  }
 });

But if we use Lambda expressions it will reduce to just 1 line, as show below,

Collections.sort(list, (Person p1, Person p2) -> p1.getName().compareTo(p2.getName()));

reduces lot of bulky codes.

Lets Discuss one example in detail:

We all are aware of Service Oriented Architecture if not please go through the tutorial 

Calling services will always be time consuming (in general all network calls are considered slow), so we handle those requests asynchronously. If the call is asynchronous then in order to get the response from the service we expect a call back to be called which will return us the result.

The following example demonstrates rather tries to simulate such a scenario,
Consider the following class “ThreadCallableClass” which will make the call to service,

//CallBack.java
package com.dhi.callback;

@FunctionalInterface
public interface CallBack {
	void operationCompelte(String args);
}


//ThreadCallableClass.java

package com.dhi.thread;

import java.util.concurrent.Callable;

import com.dhi.callback.CallBack;

public class ThreadCallableClass implements Callable<String>{
	
	public ThreadCallableClass(CallBack callBack) {
		this.callBack = callBack;
	}

	CallBack callBack;

	String str;
	
	public String getStr() {
		return str;
	}

	public void setStr(String str) {
		this.str = str;
	}
	
	@Override
	public String call() throws Exception {
		System.out.println("service is getting called with the value: " + str);
		//code to call the service to fetch some details
		callBack.operationCompelte(str);
		return "return " + str;
	}

}

//MAIN.JAVA

package com.dhi.main;

import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

import com.dhi.thread.ThreadCallableClass;

public class MainClass {

	public static void main(String[] args) {
		List<String> list = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			list.add("dhi" + i);
		}

		ArrayBlockingQueue<Runnable> arrayBlockingQueue = new ArrayBlockingQueue<Runnable>(
				1000);
		ExecutorService executorService = new ThreadPoolExecutor(10, 100, 20,
				TimeUnit.SECONDS, arrayBlockingQueue);
		for (String eachStr : list) {
			ThreadCallableClass callable = new ThreadCallableClass((String test1) -> {System.out.println(" call back getting called for the service for "+ test1);});
			callable.setStr(eachStr);
			executorService.submit(callable);
		}
		System.out.println("after thread pool");
		executorService.shutdown();
	}

}

//Person.java
package com.dhi.main;

import java.io.Serializable;

public class Person implements Serializable{
	
	String name;
	String mob;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getMob() {
		return mob;
	}
	public void setMob(String mob) {
		this.mob = mob;
	}

}


Download Code
DhiJava8LambdaFeature

Spring3 Issue with java8

Spring3 Issue with java8

Most common problem every one face during upgrading java to java8

Problem: All is well in your java spring3 web application, suddenly you start getting,







java.lang.IllegalArgumentException
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.asm.ClassReader.(Unknown Source)
at org.springframework.core.type.classreading.SimpleMetadataReader.(SimpleMetadataReader.java:52)
at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:80)
at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:101)
at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:76)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:298)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
at org.springframework.context.annotation.ConfigurationClassParser.getImports(ConfigurationClassParser.java:300)
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:230)
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:153)
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:130)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:285)
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:223)
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:630)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:461)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4961)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5455)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)


			




Solution:

This issue is due to update of java to java 8, Following are the solutions for the same,

  1. You still intend to use java8 then spring must be upgraded to 4 or
  2. Change back the version of java to java7.

Steps to change in eclipse,

  1. Right click on the project and goto properties.
  2. Select “Java Build Path”.
  3. Goto “Libraries” tab.
  4. Select JRE System Lib (sometimes the name will mislead, it will be showing java7 but internally it will be pointing to java8).
  5. Click on “Edit” button present on the right side.
  6. Select “Alternate JRE” and click on “Installed JRE”.
  7. Click on “Add” è “Standard VM”.
  8. Click on “Directory” and select the JRE7 home.
  9. An entry for jre7 will be present, check the check box present against jre7.
  10. Click “Ok”
  11. Click on “Finish”.
  12. Click “Ok” again.
  13. Click on “Project” menu and then “Clean”
  14. Wait till the build completes.

You are good with all now again.

Mathematics to solve real-world problem

Analysing problem of global warming using Mathematics

we studied mathematics in high-school, degree college but never tried to apply the concepts in real-world. I was just thinking what example I shall take and how to write a program for the same. I got to know an interesting problem, only the problem is interesting but in real the problem is really worrying.

Problem – WRITING SOME WHAT DIFFERENT PROGRAM, SIMPLE BUT DIFFERENT

in Arctic the ice surface reflects 90% of the radiation but the water surface reflects only 10% of the radiation. Considering the fact in last two decades the Arctic like places showing effect of climate change. The water surface absorbs 90% of the radiation and hence leads to chain reaction. Assuming for every 1000 gray radiation, 0.65 sqft/hr water formation from ice surface, to predict how much ice surface might vanish and what could be the impact on global warming in next two decades?

To solve this problem one must apply integration which we study in Mathematics calculus, the same problem in other way to find out the rate of change of water surface can be evaluated using differential calculus.

Let me try out this problem with a C program, definitely I still didn’t find the integration or differential calculus equation to solve, but let me prepare set of simulated data with certain assumptions.

C Program

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
/*
    Ice surface - reflects 90% of the sun light
    Water surface - reflects 10% of the sub light
    100 ice surface             - 10% absorbs
    100 water surface           - 90%
    Radiation = 100 gray
    100 * 90 = 9000 gray
    100 * 10 = 1000 gray
    assume that as temperature decreases ice surface increases, at the rate say 0.6 sqft per 1000 gray
*/
struct ICE_RADIATION_INFO{
    float iceSurfaceArea;
    float waterSurfaceArea;
    float radiationQuantity;
    
    float iceSurfaceAbsorption;
    float waterSurfaceAbsorption;
    
    float waterFormationPerHour;
};
typedef struct ICE_RADIATION_INFO ICE_RADIATION_INFO;
int main(int argc, const char * argv[])
{
    ICE_RADIATION_INFO iceRadiationSamples[100];
    short int index;
    
// Just to initialise the set of data for analysis - 
    for (index = 0; index < 100; ++index) {
        ICE_RADIATION_INFO  *iceRadiationSample = &iceRadiationSamples[index];
        // 1.5 is constant taken to generate area in floating point number
        iceRadiationSample->iceSurfaceArea = (rand() % 100) * 1.5;
        iceRadiationSample->waterSurfaceArea = iceRadiationSample->iceSurfaceArea;
     
        iceRadiationSample->radiationQuantity = (rand() % 1000) * 1.5;
        
      // absorption is as per discussion 90% from water surface and 10% from ice surface
        iceRadiationSample->iceSurfaceAbsorption = iceRadiationSample->radiationQuantity * 0.1;
        iceRadiationSample->waterSurfaceAbsorption = iceRadiationSample->radiationQuantity * 0.9;
    // with an assumption for every 1000 gray radiation, 0.65 sqft water forms
        iceRadiationSample->waterFormationPerHour = ( 0.65 * iceRadiationSample->radiationQuantity) / 1000; // 0.65 sqft/hr for 1000 gray
        /*
            Every hour 0.65 sqft water occumulation , this intern absorbs 90% of radiation , here have to apply integration
            dx/dt = 0.65
         */
    }
    
    printf("Surface Area \t Radiation \t\t Ice Absorption \t Water absorption\n");
    
    for (index = 0; index < 50; ++index) {
        ICE_RADIATION_INFO iceRadiationSample = iceRadiationSamples[index];
        printf("%f\t\t %f \t\t %f \t\t %f\n",iceRadiationSample.iceSurfaceArea,iceRadiationSample.radiationQuantity,iceRadiationSample.iceSurfaceAbsorption,iceRadiationSample.waterSurfaceAbsorption);
    }
    return 0;
}

OUTPUT –

Surface Area              Radiation                    Ice Absorption                  Water absorption

10.500000                   373.500000                  37.349998                           336.149994

109.500000                 987.000000                  98.699997                            888.299988

45.000000                   408.000000                   40.799999                           367.200012

66.000000                   1317.000000                 131.699997                         1185.300049

34.500000                   1063.500000                 106.349998                         957.150024

Jersey ClientHandlerException : A message body writer for Java type, class org.json.JSONObject, and MIME media type,

lientHandlerException: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json,

com.sun.jersey.api.client.ClientHandlerException: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json, was not found
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:149)
    at com.sun.jersey.api.client.Client.handle(Client.java:648)
    at com.sun.jersey.api.client.WebResource.handle(WebResource.java:670)
    at com.sun.jersey.api.client.WebResource.access$200(WebResource.java:74)
    at com.sun.jersey.api.client.WebResource$Builder.post(WebResource.java:563)
    at com.knowledgecess.test.service.impl.TestServiceImpl.getQuestions(TestServiceImpl.java:48)
    at com.knowledgecess.test.action.TestAction.demotest(TestAction.java:70)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:601)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:453)
    at com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:292)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:255)
    at org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:176)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265)
    at org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:236)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:190)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:90)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:243)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171)
    at com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:176)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:192)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:187)
    at com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:249)
    at org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54)
    at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:511)
    at org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:432)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1653)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
    at java.lang.Thread.run(Thread.java:722)
Caused by: com.sun.jersey.api.client.ClientHandlerException: A message body writer for Java type, class org.json.JSONObject, and MIME media type, application/json, was not found
    at com.sun.jersey.api.client.RequestWriter.writeRequestEntity(RequestWriter.java:288)
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler._invoke(URLConnectionClientHandler.java:204)
    at com.sun.jersey.client.urlconnection.URLConnectionClientHandler.handle(URLConnectionClientHandler.java:147)
    ... 74 more
knowledgecess







Solution :
Just find jsonInput, second parameter for post() in the below code add toString to jsoninput data

ClientResponse clientResponse = webResource
                .accept(MediaType.APPLICATION_JSON)
                .type(MediaType.APPLICATION_JSON)
                .post(ClientResponse.class, jsonInput);

FIX –

ClientResponse clientResponse = webResource
.accept(MediaType.APPLICATION_JSON)
.type(MediaType.APPLICATION_JSON)
.post(ClientResponse.class, jsonInput.toString());

HTML Style , CSS properties Browser compatibility

CSS Proprties and Browser compatibility

CSS Properties :

1) content

  Never use content to set background image for div, instead use background-image :
Example 

			



 
.divItem{
    position: absolute;
    top: 12px;
    right: 11px;
    width: 40px;
    height: 40px;
    content: url(../../images/elective.png)
}
 
The above properties works fine in Chrome, but in firefox the image doesn't appear.
.divItem{
    position: absolute;
    top: 12px;
    right: 11px;
    width: 40px;
    height: 40px;
    content: url(../../images/elective.png)
}

2) background-size

.divItem{
    position: absolute;
    top: 12px;
    right: 11px;
    width: 40px;
    height: 40px;
    background-image: url(../../images/elective.png);
    -webkit-background-size: 100%;
    background-size: 100%
}

-webkit-background-size: is specifically for those browsers which support web kit layout rendering engine.
Note : http://en.wikipedia.org/wiki/WebKit






Opera supports 
-o-background-size:
But in latest opera versions, webkit itself is sufficient

3) box-shadow

.divItem{
   border: 1px solid #08c;
   box-shadow: 0 1px 0 rgba(255, 255, 255, 0.25), inset 0 3px 6px rgba(0, 0, 0, 0.25)
 }

This doesn't works in Firefox,

.divItem
{
   border: 1px solid #08c;
  -moz-box-shadow: 0 1px 0 rgba(255, 255, 255, 0.25), inset 0 3px 6px rgba(0, 0, 0, 0.25);
  -webkit-box-shadow: 0 1px 0 rgba(255, 255, 255, 0.25), inset 0 3px 6px rgba(0, 0, 0, 0.25);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.25), inset 0 3px 6px rgba(0, 0, 0, 0.25)
 }


4) border-radius:

.divItem{
    border-radius: 100px;
}

For Firefox and other browsers
.divItem{
    -moz-border-radius: 100px;
    -webkit-border-radius: 100px;
    border-radius: 100px;
}


5) innerText :
innerText is old style of using in older version of internet explorer.
Instead of using innerText , use textContent or innerHTML, this works fine in all browsers.

User innerHTML Or contentText

 

Java Jar files; Java Libraries; JSON lib;

Java Jar files and Uses

JAR:  aopalliance-repackaged-2.2.0.jar 

Usage: aop alliance will be internally used by

Note : Google Guice Core is a powerful library released by Google for dependency injection, this works with java 6 and above ( download )

JAR:  apache-mime4j-0.6.jar

Usage: apache mime will be used for mime message parsing. This jar internally used by 

  • commons-io
  • commons-logging
  • junit like testing libraries
  • log4j 

JAR : commons-io

Usage – commons io provides utility classes, stream implementations, file filters,file comparators, endian transformation classes

JAR : asm-3.3.jar

Usage : asm jar will be used to analyse the byte code and analyse the frameworks

Note: asm is used by certain code generation libraries like cglib

JAR : gson-2.3.jar 

Usage : gson used to convert java objects into json object. Can be used in struts and springs to convert java objects. ( Documentation )

 JAR : persistence-api-1.0.jar

 Usage : The Java Persistence API provides Java developers with an object/relational mapping facility for managing relational data in Java applications

Dependencies :

  • Servlet-API
  • Javax.inject 

JAR : hk2-api-2.2.0.jar 

Usage : This is called hundred kilobyte kernal for glassfish server, It forma the core glassfish server architecture

 

Hibernate NoSuchBeanDefinitionException : Java Hibernate Exception

Hibernate NoSuchBeanDefinitionException : Java Hibernate Exception

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.cess.service.Employee.EmployeeService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true), @org.springframework.beans.factory.annotation.Qualifier(value=EmployeeServiceImpl)} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:949) at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:818) at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:730) at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486) … 25 more

Solution – 

This issue is a strange issue in hibernate autowire for bean objects, the solution will be as follows but no technical description why so ? 🙂

@Autowired
@Qualifier("EmployeeServiceImpl")
EmployeeService employeeService;  //EmployeeService is an interface


			




Change the above @Qualifier as below 
@Qualifier("employeeServiceImpl")

Note : the only change is instead of capital E in EmployeeServiceImpl, it should be small 'e' employeeServiceImpl
If it is reverse case then do make it Capital .

Hibernate QueryException : could not resolve property:

Hibernate QueryException :  could not resolve property:

org.hibernate.QueryException: could not resolve property: DP of: com.cess.pojo.Customer
at org.hibernate.persister.entity.AbstractPropertyMapping.propertyException(AbstractPropertyMapping.java:67)
at org.hibernate.persister.entity.AbstractPropertyMapping.toType(AbstractPropertyMapping.java:61)
at org.hibernate.persister.entity.AbstractEntityPersister.getSubclassPropertyTableNumber(AbstractEntityPersister.java:1402)
at org.hibernate.persister.entity.BasicEntityPropertyMapping.toColumns(BasicEntityPropertyMapping.java:54)
at org.hibernate.persister.entity.AbstractEntityPersister.toColumns(AbstractEntityPersister.java:1377)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumns(CriteriaQueryTranslator.java:457)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getColumnsUsingProjection(CriteriaQueryTranslator.java:417)
at org.hibernate.criterion.SimpleExpression.toSqlString(SimpleExpression.java:68)
at org.hibernate.loader.criteria.CriteriaQueryTranslator.getWhereCondition(CriteriaQueryTranslator.java:357)
at org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:113)
at org.hibernate.loader.criteria.CriteriaJoinWalker.(CriteriaJoinWalker.java:82)
at org.hibernate.loader.criteria.CriteriaLoader.(CriteriaLoader.java:91)
at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1577)
at org.hibernate.impl.CriteriaImpl.list(CriteriaImpl.java:306)
at com.cess.dao.impl.CusomerDaoImpl$1.execute(CustomerDaoImpl.java:77)
at com.cess.framework.TransactionWrapper.run(TransactionWrapper.java:41)
at com.cess.dao.impl.CustomerDaoImpl.getCustomers(CustomerDaoImpl.java:43)
at com.cess.service.impl.CustomerServiceImpl.getCustomers(customerServiceImpl.java:39)
at com.cess.controller.CustomerController.Customers(CustomerController.java:39)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at org.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:219)
at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:746)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:687)
at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:80)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:925)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:856)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:915)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:822)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:796)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:936)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1004)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1653)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)

			




Solution –
Instead of using nested paths directly in Criteria API (unlike HQL), create nested criteria instances and use aliases on each “entity.property”
Example –







Criteria criteria = sessionObject
.createCriteria(Customer.class, "C")
.createAlias("C.department", "D")
.createAlias("D.Section", "S")
.createAlias("S.SubSection", "SB")

SEVERE: Exception sending context initialized event to listener instance of class

SEVERE: Exception sending context initialized event to listener instance of class

SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping#0': Invocation of init method failed; nested exception is java.lang.IllegalStateException: Ambiguous mapping found. Cannot map '/project' bean method
public java.util.ArrayList com.cess.controller.UserProjectController.UserProject(com.cess.pojo.Class)
to {[/get],methods=[POST],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already '/userinfo' bean method
public java.lang.String com.cess.controller.UserController.userInfo(com.cess.pojo.User) mapped.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1486)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:524)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:461)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:607)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:383)
at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:283)
at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4791)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5285)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.lang.IllegalStateException: Ambiguous mapping found. Cannot map '/project' bean method
public java.util.ArrayList com.cess.controller.UserProjectController.UserProject(com.cess.pojo.Class)
to {[/get],methods=[POST],params=[],headers=[],consumes=[],produces=[],custom=[]}: There is already '/userinfo' bean method
public java.lang.String com.cess.controller.UserController.userInfo(com.cess.pojo.User) mapped.
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.registerHandlerMethod(AbstractHandlerMethodMapping.java:179)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.detectHandlerMethods(AbstractHandlerMethodMapping.java:145)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.initHandlerMethods(AbstractHandlerMethodMapping.java:107)
at org.springframework.web.servlet.handler.AbstractHandlerMethodMapping.afterPropertiesSet(AbstractHandlerMethodMapping.java:87)
at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerMapping.afterPropertiesSet(RequestMappingHandlerMapping.java:150)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1483)
... 22 more

Solution
If your controller class are as follows








			




@Controller("/userinfo")
public class UserController {
@RequestMapping(method=RequestMethod.POST)
 public String userInfo(@RequestBody User user){
 }
}

@Controller("/userproject") 
public class UserProjectController {

@RequestMapping(method=RequestMethod.POST)
  public String userProject(@RequestBody UserProject userProject){
  }
}

//Then Use value Element of @RequestMapping as follows
@Controller
public class UserController {
 
 @RequestMapping(value = "/getuserinfo", method=RequestMethod.POST)
 
  public String userInfo(@RequestBody User user){

  }
}


@Controller
public class UserProjectController {
 //Note value in both controller requestMapping should be different
 
 @RequestMapping(value = "/getuserproject",method=RequestMethod.POST)
  public String userProject(@RequestBody UserProject userProject){

  }
}