Java pass by value vs pass by reference

Hi guys,

This blog is about pass by value and pass by reference concept and understanding. Primitives are always pass by value, objects are always pass by reference.

If only the fields of the parameter are modified in the called method , the changes will be reflected in the calling method . If the reference of the parameter is assigned to a new object , the change will not be reflected in calling method .

Declarative Exception handling in struts

Declarative programming is a way to separate Control from computation logic . Exception handling in java is usually done using try catch and throws . In jsp we can handle exceptions using errorPage attribute of page declarative . Any exception occurred will be routed to the value of errorPage attribute . In addition to this struts offer similar way of handling exception . Use exception tags in StrutsConfig.xml to declare excpetion handling . All exception tags should be enclosed under global-Exception tag. Type of exception is mentioned in type attribute , exception message is mentioned in key attribute and the page which is called in case of exception is mentioned in path attribute of exception tag . The action exception message is picked from MessageResource.properties file for the key in key attribute .

Advice in spring

Advice is the action taken up by an Aspect at a join point . You can use a specific advice based when you want it to be executed . Before Advice : If you want your advice to be executed before the join point use Before Advice .

Hashcode in java

What is the use of hashcode in java.
Hashcode is very important in java . in object class , you will have a method hashcode , which will give the hashcode of an object.

hashcode is used to check whether two objects are equal or not . If two objects have a different hashcode they are definately not equal , but if their hashcode is same ,it does not guarantee both objects to be same .

hibernate pooling

what is hibernate pooling ?

aspect in spring

Aspect is modulerization of a concern that cuts accross multiple classes . Take an example of exception handling ,consider exception handling as an Aspect . In a program if an exception occurs it is an example join point as per spring nomenclature . At a join point action taken by Aspect is called an Advice , so if an ExceptionHandlingAspect calls logException(Exception e) ,logException is an example of advice . All advices has a pointcut expression , if for a join point , point cut expression is true , then the advice is executed at the join point .

Sorting list contents

List content is sorted using Collections.sort(listObject,comparatorObject);
For example if have list of Student object and you want to sort it, then you need to create a new object of type Comparator. The logic of comparision is written in

int compare(Object object1,Object object2)

While overriding compare method you need to return the following :
Positive integer : if object 1 > object 2
Negative integer : if object 2> object 1
Zero : if object 1 = object 2

This logic will allow your list to be sorted in ascending order.