TechFAQ

Error

An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch. Most such errors are abnormal conditions. The ThreadDeath error, though a "normal" condition, is also a subclass of Error because most applications should not try to catch it.

A method is not required to declare in its throws clause any subclasses of Error that might be thrown during the execution of the method but not caught, since these errors are abnormal conditions that should never occur.

java.lang.Object
  java.lang.Throwable
      java.lang.Error
					

Exception

The class Exception and its subclasses are a form of Throwable that indicates conditions that a reasonable application might want to catch.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
					

RuntimeException

RuntimeException is the superclass of those exceptions that can be thrown during the normal operation of the Java Virtual Machine.

A method is not required to declare in its throws clause any subclasses of RuntimeException that might be thrown during the execution of the method but not caught.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
					

Thrown to indicate that an array has been accessed with an illegal index. The index is either negative or greater than or equal to the size of the array.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.IndexOutOfBoundsException
                  java.lang.ArrayIndexOutOfBoundsException
					

ClassCastException

Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance. For example, the following code generates a ClassCastException:

Object x = new Integer(0);
System.out.println((String)x);
					

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.ClassCastException
					

IllegalArgumentException

Thrown to indicate that a method has been passed an illegal or inappropriate argument.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.IllegalArgumentException
					

IllegalStateException

Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.IllegalStateException
					

NullPointerException

Thrown when an application attempts to use null in a case where an object is required. These include:

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.NullPointerException
					

NumberFormatException

Thrown to indicate that the application has attempted to convert a string to one of the numeric types, but that the string does not have the appropriate format.

java.lang.Object
  java.lang.Throwable
      java.lang.Exception
          java.lang.RuntimeException
              java.lang.IllegalArgumentException
                  java.lang.NumberFormatException
					

AssertionError

Thrown to indicate that an assertion has failed. The seven one-argument public constructors provided by this class ensure that the assertion error returned by the invocation:

new AssertionError(expression)
					

java.lang.Object
  java.lang.Throwable
      java.lang.Error
          java.lang.AssertionError					
					

ExceptionInInitializerError

Signals that an unexpected exception has occurred in a static initializer. An ExceptionInInitializerError is thrown to indicate that an exception occurred during evaluation of a static initializer or the initializer for a static variable.

As of release 1.4, this exception has been retrofitted to conform to the general purpose exception-chaining mechanism. The "saved throwable object" that may be provided at construction time and accessed via the getException() method is now known as the cause, and may be accessed via the Throwable.getCause() method, as well as the aforementioned "legacy method."

java.lang.Object
  java.lang.Throwable
      java.lang.Error
          java.lang.LinkageError
              java.lang.ExceptionInInitializerError
					

StackOverflowError

Thrown when a stack overflow occurs because an application recurses too deeply.

java.lang.Object
  java.lang.Throwable
      java.lang.Error
          java.lang.VirtualMachineError
              java.lang.StackOverflowError
					

NoClassDefFoundError

Thrown if the Java Virtual Machine or a ClassLoader instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the new expression) and no definition of the class could be found.

The searched-for class definition existed when the currently executing class was compiled, but the definition can no longer be found.

java.lang.Object
  java.lang.Throwable
      java.lang.Error
          java.lang.LinkageError
              java.lang.NoClassDefFoundError