Recognize situations that will result in any of the following being thrown: ArrayIndexOutOfBoundsException, ClassCastException, IllegalArgumentException, IllegalStateException, NullPointerException, NumberFormatException, AssertionError, ExceptionInInitializerError, StackOverflowError or NoClassDefFoundError. Understand which of these are thrown by the virtual machine and recognize situations in which others should be thrown programatically.

Recognize situations that will result in any of the following being thrown: ArrayIndexOutOfBoundsException, ClassCastException, IllegalArgumentException, IllegalStateException, NullPointerException, NumberFormatException, AssertionError, ExceptionInInitializerError, StackOverflowError or NoClassDefFoundError. Understand which of these are thrown by the virtual machine and recognize situations in which others should be thrown programatically.
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ArrayIndexOutOfBoundsException

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:

Calling the instance method of a null object.
Accessing or modifying the field of a null object.
Taking the length of null as if it were an array.
Accessing or modifying the slots of null as if it were an array.
Throwing null as if it were a Throwable value.
Applications should throw instances of this class to indicate other illegal uses of the null object.

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

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Recognize the effect of an exception arising at a specified point in a code fragment. Note that the exception may be a runtime exception, a checked exception, or an error.	Home	Chapter 3. API Contents