Error: Could not find or load main class

If you are getting the error Error: Could not find or load main class when you try to run any java program in using eclipse then you could perform any of the following resolutions to fix the issue. If a single resolution doesn't work for you then perform the next solution which is given below.

1. Go to your project path for e.g. C:\Users\java\rashid\jorvee > open .classpath file and verify all the entries given in this file are actually exist in your system. Below is the sample file.

<?xml version="1.0" encoding="UTF-8"?>

<classpath>

 <classpathentry exported="true" kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.8"/>

 <classpathentry kind="src" path="src"/>

 <classpathentry exported="true" kind="lib" path="C:/Users/java/rashid/java-json.jar/java-json.jar"/>

 <classpathentry kind="output" path="bin"/>

</classpath>

2. Go to run > run configuration > classpath> Select Project > Advance > select option add folder and select the bin folder where your .class file get stored.

3. There might be a possibility that there is no classpath set for java class files. Please go ahead and set classpath manually by executing the below command on cmd.

javac -cp . PackageName/*.java

4. In some cases we have found that Java build path is not set up for the project, or somehow it gets removed from the directory then go ahead and set your project classpath here. Add your project in the source tab and JRE in libraries tab.

Project > Properties > Java Build Path >

AEM Sling Models

What is the Sling Models?

While working with Sling in Adobe Experience Manager[AEM]; we need to map our objects (Java backend object) with Apache Sling resource. Many Sling projects want to be able to create model objects - POJOs which are automatically mapped from Sling objects, typically resources, but also request objects. With the help of sling models, we can define a model object "a Java class or interface" and map that object with sling resources. Before sling models, we are achieving these all using WCMUse and WCMUsePojo which are quite similar to sling models.

To use the Sling Models in your project first you need to add the following dependency in your pom.xml file.

<dependency>
<groupId>org.apache.sling</groupId>
<artifactId>org.apache.sling.model.api</artifactId>
<version>1.3.0</version>
<scope>provided</scope>
<dependency>

@Model annotation

To map a java class or interface with sling resource we use @Model annotation and could pass an adaptables parameter into it to make a class adaptable by sling model.

@Model(adaptables = Resource.class)
public class RashidJorvee {

//Write your code here

}

or

@Model(adaptables = SlingHttpServletRequest.class)
public class RashidJorvee {

//Write your code here

}

@Inject annotation

Using @Inject we can make a filed and method injectable. We can also inject a constructor using @Inject annotation. We also use @Inject with @Filter option to pass the reference to an available OSGi service, which works similarly as @Refernce.

@Inject
private String firstName;

@Inject

String getName();

There are many other options we have which makes injection make accurate and exact. like following

@Named

To match the name of the property with field name

@Via

Change the adaptable object instead of using the original adaptable object

@Default

To assign a defult value to any field or property.

@Filter

Filter an OSGi service

@Optional

Mark filed and method injection optional.

@Source

To manage the ambiguity between injector, it helps us to tie the injected field or method to a particular injector.

@PostConstruct annotation

Using PostConstruct annotation we can invoke any method which we want to execute when all injection has been completed for that class. This is act as similar to the activate() method which we use for WCMUsePojo or WCMUse.

@PostConstruct

public void letMeExecuteFirst() {

//Write your code here;

}

Public provident fund (PPF)

Public provident fund(PPF) is the safest investment available in the market for long time investment at least more than 7 years. Actual maturity of PPF is for 15 years and a person cannot withdraw his/her money completely before 15 years, but they can withdraw some amount partially after seven years from the opening of the account.

PPF gives the highest rate of interest in any investment, and RoI is always same with PF and VPF account, as these all are the investment plan from the government of India.

Why you should invest in PPF?

Your money will safe in hand of Govt.
PPF account is actually managed by India post(post office).
A high rate of interest.
Tax exemption under 80 C.
Interest earned on PPF amount in non-taxable
You can open your account at any time with minimum/subscription amount of 500 rupees.
Within a financial year you maximum you could submit 150,000 rupees.
Funds can be deposited to PPF account, only 12 times in a Financial Year.
Premature closure is not allowed before 15 years, but you could partially withdraw after seven years.
You can take a loan on this account after the 3rd financial year.

Where to open a PPF account?

PPF is a saving and tax saving scheme of GoI and managed by the post office of India. You could open PPF account with any post office or with any public or private banks.

for more details and current benefits of scheme you could visit Post-Office-Saving-Schemes | indiapost.gov.in

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