Core Java :What class of exceptions are generated by the Java run-time system?

The Java runtime system generates RuntimeException and Error exceptions.

Core Java :Which non-Unicode letter characters may be used as the first character of an identifier?

The non-Unicode letter characters $ and _ may appear as the first character of an identifier

Core Java : What happens when you invoke a thread's interrupt method while it is sleeping or waiting?

When a task's interrupt() method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown.

Core Java : What is casting?

There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.

Core Java : What is the difference between a Choice and a List?

A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice. A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.

Core Java : Name Container classes

Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane

When is the finally clause of a try-catch-finally statement executed?

The finally clause of the try-catch-finally statement is always executed unless the thread of execution terminates or an exception occurs within the execution of the finally clause.

Core Java :When does the compiler supply a default constructor for a class?

The compiler supplies a default constructor for a class if no other constructors are provided.

Core Java : How does multithreading take place on a computer with a single CPU?

The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.

Core Java : Which Math method is used to calculate the absolute value of a number?

The abs() method is used to calculate absolute values.

Can an exception be rethrown?

Yes, an exception can be rethrown.

Core Java :What is the purpose of the File class?

The File class is used to create objects that provide access to the files and directories of a local file system.

Core Java : What is the difference between the paint() and repaint() methods?

The paint() method supports painting via a Graphics object. The repaint() method is used to cause paint() to be invoked by the AWT painting thread.

Core Java : What is the difference between static and non-static variables?

A static variable is associated with the class as a whole rather than with specific instances of a class. Nonstatic variables take on unique values with each object instance.

Core Java : What modifiers can be used with a local inner class?

A local inner class may be final or abstract.

Core Java : What is the Collection interface?

The Collection interface provides support for the implementation of a mathematical bag - an unordered collection of objects that may contain duplicates.

Core Java : What advantage do Java's layout managers provide over traditional windowing systems?

Java uses layout managers to lay out components in a consistent manner across all windowing platforms.

Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accomodate platform-specific differences among windowing systems.

Core Java :How are the elements of a GridBagLayout organized?

The elements of a GridBagLayout are organized according to a grid. However, the elements are of different sizes and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.

Core Java : What is the difference between a while statement and a do statement?

A while statement checks at the beginning of a loop to see whether the next loop iteration should occur. A do statement checks at the end of a loop to see whether the next iteration of a loop should occur. The do statement will always execute the body of a loop at least once.

How can a GUI component handle its own events?

A component can handle its own events by implementing the required event-listener interface and adding itself as its own event listener.