Throwable

Name

Synopsis

• Class Name:
• java.lang.Throwable
• Superclass:
• java.lang.Object
• Immediate Subclasses:
• java.lang.Error, java.lang.Exception
• Interfaces Implemented:
• java.io.Serializable
• Availability:
• JDK 1.0 or later

Description

The Throwable class is the superclass of all objects that can be thrown by the throw statement in Java. This is a requirement of the throw statement.

A Throwable object can have an associated message that provides more detail about the particular error or exception that is being thrown.

The Throwable class provides a method that outputs information about the state of the system when an exception object is created. This method can be useful in debugging Java programs.

The subclasses of Throwable that are provided with Java do not add functionality to Throwable. Instead, they offer more specific classifications of errors and exceptions.

Class Summary

public class java.lang.Throwable extends java.lang.Object implements java.lang.Serializable {
 // Constructors public Throwable();
public Throwable(String message); // Instance Methods public native Throwable fillInStackTrace();
public String getLocalizedMessage(); // New in 1.1 public String getMessage();
public void printStackTrace();
public void printStackTrace(PrintStream s);
public void printStackTrace(PrintWriter s); // New in 1.1 public String toString();
}

Constructors

Throwable

public Throwable()

• Description
• Creates a Throwable object with no associated message. This constructor calls fillInStackTrace() so that information is available for printStackTrace().

public Throwable(String message)

• Parameters
• • message
  • A message string to be associated with the object.
• Description
• Create a Throwable object with an associated message. This constructor calls fillInStackTrace() so that information is available for printStackTrace().

Instance Methods

fillInStackTrace

public native Throwable fillInStackTrace()

• Returns
• A reference to this object.
• Description
• This method puts stack trace information in this Throwable object. It is not usually necessary to explicitly call this method, since it is called by the constructors of the class. However, this method can be useful when rethrowing an object. If the stack trace information in the object needs to reflect the location that the object is rethrows from, fillInStackTrace() should be called.

getLocalizedMessage

public String getLocalizedMessage()

• Availability
• New as of JDK 1.1
• Returns
• A localized version of the String object associated with this Throwable object, or null if there is no message associated with this object.
• Description
• This method creates a localized version of the message that was associated with this object by its constructor.

  The getLocalizedMessage() method in Throwable always returns the same result as getMessage(). A subclass must override this method to produce a locale-specific message.

getMessage

public String getMessage()

• Returns
• The String object associated with this Throwable object, or null if there is no message associated with this object.
• Description
• This method returns any string message that was associated with this object by its constructor.

printStackTrace

public void printStackTrace()

• Description
• This method outputs the string representation of this Throwable object and a stack trace to System.err.

public void printStackTrace(PrintStream s)

• Parameters
• • s
  • A java.io.PrintStream object.
• Description
• This method outputs the string representation of this Throwable object and a stack trace to the specified PrintStream object.

public void printStackTrace(PrintStream w)

• Availability
• New as of JDK 1.1
• Parameters
• • s
  • A java.io.PrintWriter object.
• Description
• This method outputs the string representation of this Throwable object and a stack trace to the specified PrintWriter object.

toString

public String toString()

• Returns
• A string representation of this object.
• Overrides
• Object.toString()
• Description
• This method returns a string representation of this Throwable object.

Inherited Methods

See Also

Errors; Exceptions; Object