Java Interview Questions - Page 9
Question: Which package has light weight components?
Answer: javax.Swing package. All
components in Swing, except JApplet, JDialog, JFrame and JWindow are
lightweight components.
Question: What are peerless components?
Answer: The peerless components are called
light weight components.
Question: What is the difference between the Font and FontMetrics classes?
Answer: The
FontMetrics class is used to define implementation-specific properties, such
as ascent and descent, of a Font object.
Question: What happens when a thread cannot acquire a lock on an object?
Answer: If a
thread attempts to execute a synchronized method or synchronized statement
and is unable to acquire an object's lock, it enters the waiting state until
the lock becomes available.
Question: What is the difference between the Reader/Writer class hierarchy and
the InputStream/OutputStream class hierarchy?
Answer: The Reader/Writer class
hierarchy is character-oriented, and the InputStream/OutputStream class
hierarchy is byte-oriented.
Question: What classes of exceptions may be caught by a catch clause?
Answer: A catch
clause can catch any exception that may be assigned to the Throwable type.
This includes the Error and Exception types.
Question:What is the difference between throw and throws keywords?
Answer: The throw
keyword denotes a statement that causes an exception to be initiated. It
takes the Exception object to be thrown as argument. The exception will be
caught by an immediately encompassing try-catch construction or propagated
further up the calling hierarchy. The throws keyword is a modifier of
a method that designates that exceptions may come out of the mehtod, either
by virtue of the method throwing the exception itself or because it fails to
catch such exceptions that a method it calls may throw.
Question: If a class is declared without any access modifiers, where may the
class be accessed?
Answer: A class that is declared without any access modifiers is
said to have package or friendly access. This means that the class can only
be accessed by other classes and interfaces that are defined within the same
package.
Question: What is the Map interface?
Answer: The Map interface replaces the JDK 1.1
Dictionary class and is used associate keys with values.
Question: Does a class inherit the constructors of its
superclass?
Answer: A class does
not inherit constructors from any of its superclasses.
Question: Name primitive Java types.
Answer: The primitive types are byte, char, short, int, long, float, double, and
boolean.