Java Core Classes and Threads

Java's garbage collector automatically reclaims memory from objects that are no longer reachable. An object becomes eligible for garbage collection when there are no live references to it in the running program. This is a fundamental memory management feature in Java.

In JSP custom tag handlers, getParent() returns the closest enclosing tag handler. This is part of the Tag and BodyTag interfaces. getAncestor(), findAncestor(), and findParent() are not standard methods in the JSP tag handler API. The getParent() method allows a nested tag to communicate with its parent tag, which is essential for cooperative tag handler patterns.

System.gc() suggests to the JVM that garbage collection should run. Note that this is only a suggestion - the JVM may ignore it. System.free(), System.setGarbageCollection(), and System.out.gc() are not valid Java methods. The gc() method is in the System class, not in PrintStream (which System.out is).

When adding a duplicate element to a Set, the add() method returns false but does not throw an exception. Sets are designed to contain only unique elements - duplicates are simply ignored. The add() method's return value indicates whether the element was actually added (true if it was a new element, false if it was a duplicate). No compile-time or runtime error occurs.

In a unidirectional relationship Foo→Bar, only Foo knows about Bar (Foo has a getBar() method, Bar has NO getFoo() method). After f2.setBar(f1.getBar()), f2 now points to b1. Since the relationship is unidirectional from Foo to Bar, b1 has NO reference to any Foo. b1.getFoo() doesn't exist (not that it's null - the method doesn't exist). For the unidirectional case, b2.getFoo() also doesn't exist - but the question implies b2 now has no incoming reference from f2.

Triggers in JProbe allow developers to control profiling actions dynamically by tying them to specific events in the program's execution, such as entering or exiting a method. The distractors describe general profiling behavior or native method encapsulation rather than the specific automation purpose of triggers.

Leak Doctor View is specifically designed in JProbe to help identify memory leaks by tracking object allocations, garbage collection cycles, and objects that persist longer than expected. It analyzes reference chains and helps pinpoint why objects are not being garbage collected. Heap View shows overall memory distribution, Instance View lists individual objects, and Allocation View tracks where objects were created - none specifically target leak detection like Leak Doctor.

Overriding methods in Java can throw any unchecked (runtime) exceptions regardless of what the overridden method declares. This includes RuntimeException, Error, and their subclasses. Checked exceptions are more restricted - overriding methods cannot throw broader checked exceptions than the overridden method.

GetRoProperty is a generic QTP method that retrieves any runtime property of an object, including 'items count' for a WebList. The other options (GetList, GetItem, GetItemsCount) are not standard QTP methods. GetRoProperty('items count') returns the number of items as a string or number.

The ChildObjects method returns a collection object containing all child objects matching the description properties you specify. It returns a Collection object (not a simple count or boolean), which you can then iterate through using .Count and .Item(index). This is essential for dynamic object handling when you don't know exactly how many objects exist.

Property-Map-Value passes a single row input to a Rule-Obj-MapValue. Property-Map-ValuePair passes a single row input AND a single column input to the Rule-Obj-MapValue, allowing lookup based on two dimensions. This is the key difference between the two methods.

The Property-Set method is the standard and recommended way to update property values in PEGA activity steps, providing proper framework integration. Java methods break abstraction, AtSetValue is not a standard PEGA method, and {PropertyName INPUT} is a reference syntax not a method for setting values.

wait() and notify() are defined in java.lang.Object class, making them available to all objects since every class inherits from Object. They are not in Thread, Runnable, or ThreadGroup classes.

HashTable allows data retrieval by unique key and is the standard .NET collection for key-value pairs. NamedValueCollection is for multiple values per key, SortedList maintains sort order, and the question specifically asks for unique key retrieval which HashTable provides.

The key difference is null handling. If S is null, S.ToString() throws a NullReferenceException because you're calling a method on a null reference. Convert.ToString(S) handles null gracefully and returns an empty string or null without throwing an exception. This makes Convert.ToString safer when null values are possible.