Java Core Classes and Threads

When an exception is thrown in a try block and no matching catch block exists, the exception propagates up the call stack. The method throws the exception to its caller, following Java's exception propagation mechanism. This allows higher-level methods to handle the exception or continue propagating it. The program does not halt immediately, ignore the exception, or fail to compile - this is legal Java code.

A finally block is ALWAYS executed after execution leaves the try block, regardless of how it exits - whether via normal completion, a caught or uncaught exception, return, break, or continue statements. This guarantee makes finally blocks ideal for cleanup code that must run under all circumstances. The finally block executes even when no exception occurs or when the exception is caught.

Pega recommends using standard PRPC rule types and built-in functions instead of custom Java steps because they are optimized, maintainable, and avoid security risks. Java steps should only be used when absolutely necessary.

The escape() function in ActionScript converts a parameter to a string and encodes it in URL-encoded format. All non-alphanumeric characters (except some like * @ - _ . +) are replaced with %XX hexadecimal sequences. For example, a space becomes %20. This is essential for passing data safely in URLs.

EJB home interfaces for entity beans have strict naming conventions. Methods starting with 'create' (like createCustomer) are reserved for create methods. Methods starting with 'find' (like findAllCustomers) are reserved for finder methods. Method names like removeTheCustomer conflict with EQL reserved keywords. The method name 'create' alone is a reserved word in EJB context. Only retrieveCustData() doesn't violate these conventions.

Entity bean home interfaces can have zero or more create methods. Unlike session beans which must have at least one create method, entity beans are not required to have any create methods - they can rely exclusively on finder methods to locate existing entities. When create methods are defined, there's no upper limit on how many can exist.

According to the EJB specification, finder methods returning a Collection must return an empty collection if no matching entities are found. ObjectNotFoundException is only thrown for single-object finder methods (like findByPrimaryKey) when a match is missing, while automatic entity creation never occurs on a failed lookup.

When an ejbCreate is invoked, the container must subsequently invoke the corresponding ejbPostCreate with the same parameters. This post-create method allows additional initialization after the primary key is assigned. ejbActivate() is for passivation/activation, ejbStore() is for synchronization, and ejbFindByPrimaryKey() is a finder method - none are automatically invoked after ejbCreate.

The perform() method in a Perform node must be public, return void, and declare throws Exception to handle any exceptions that may occur during execution. The method needs to throw Exception rather than return boolean because the framework handles exception propagation. Static methods are not used for instance-level perform nodes.

Tracing the code: after creating the array and String, assigning 'students[0] = studentName' creates a second reference to 'Peter Parker'. Setting 'studentName = null' only removes one reference. The array object is still referenced by 'students' variable, and the String object is still referenced by 'students[0]'. Neither object loses all references, so neither is eligible for garbage collection.

X is a method header because it includes modifiers (public, final), return type (String), method name (getDetails), parameters (File file, String key), and throws clause. Y is a method signature because it only includes the method name and parameter types without modifiers or return type.

Backing beans (managed beans) in JSF define both properties and methods. Methods can include action handlers (for button clicks), value change listeners, and validation logic. These methods are bound to UI component events, bridging the view and model layers.

sendError() and sendStatus() are methods of HttpServletResponse that send HTTP error responses and status codes to the client. HttpServletRequest handles request data, while ServletRequest and ServletResponse are generic interfaces that HttpServlet extends.

The code checks if check4Biz(storeNum) is not null, meaning the method must return a reference type (an object, not a primitive). String is a reference type and can be null. boolean, int, and char are primitive types and cannot be null.