throwable.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

            throw new IllegalArgumentException("Self-causation not permitted");
        this.cause = cause;
        return this;
    }

    /**
     * Returns a short description of this throwable.
     * If this <code>Throwable</code> object was created with a non-null detail
     * message string, then the result is the concatenation of three strings: 
     * <ul>
     * <li>The name of the actual class of this object 
     * <li>": " (a colon and a space)
     * <li>The result of the {@link #getMessage} method for this object 
     * </ul>
     * If this <code>Throwable</code> object was created with a <tt>null</tt>
     * detail message string, then the name of the actual class of this object
     * is returned. 
     *
     * @return a string representation of this throwable.
     */
    public String toString() {
        String s = getClass().getName();
        String message = getLocalizedMessage();
        return (message != null) ? (s + ": " + message) : s;
    }

    /**
     * Prints this throwable and its backtrace to the 
     * standard error stream. This method prints a stack trace for this 
     * <code>Throwable</code> object on the error output stream that is 
     * the value of the field <code>System.err</code>. The first line of 
     * output contains the result of the {@link #toString()} method for 
     * this object.  Remaining lines represent data previously recorded by 
     * the method {@link #fillInStackTrace()}. The format of this 
     * information depends on the implementation, but the following 
     * example may be regarded as typical: 
     * <blockquote><pre>
     * java.lang.NullPointerException
     *         at MyClass.mash(MyClass.java:9)
     *         at MyClass.crunch(MyClass.java:6)
     *         at MyClass.main(MyClass.java:3)
     * </pre></blockquote>
     * This example was produced by running the program: 
     * <pre>
     * class MyClass {
     *     public static void main(String[] args) {
     *         crunch(null);
     *     }
     *     static void crunch(int[] a) {
     *         mash(a);
     *     }
     *     static void mash(int[] b) {
     *         System.out.println(b[0]);
     *     }
     * }
     * </pre>
     * The backtrace for a throwable with an initialized, non-null cause
     * should generally include the backtrace for the cause.  The format
     * of this information depends on the implementation, but the following
     * example may be regarded as typical:
     * <pre>
     * HighLevelException: MidLevelException: LowLevelException
     *         at Junk.a(Junk.java:13)
     *         at Junk.main(Junk.java:4)
     * Caused by: MidLevelException: LowLevelException
     *         at Junk.c(Junk.java:23)
     *         at Junk.b(Junk.java:17)
     *         at Junk.a(Junk.java:11)
     *         ... 1 more
     * Caused by: LowLevelException
     *         at Junk.e(Junk.java:30)
     *         at Junk.d(Junk.java:27)
     *         at Junk.c(Junk.java:21)
     *         ... 3 more
     * </pre>
     * Note the presence of lines containing the characters <tt>"..."</tt>.
     * These lines indicate that the remainder of the stack trace for this
     * exception matches the indicated number of frames from the bottom of the
     * stack trace of the exception that was caused by this exception (the
     * "enclosing" exception).  This shorthand can greatly reduce the length
     * of the output in the common case where a wrapped exception is thrown
     * from same method as the "causative exception" is caught.  The above
     * example was produced by running the program:
     * <pre>
     * public class Junk {
     *     public static void main(String args[]) { 
     *         try {
     *             a();
     *         } catch(HighLevelException e) {
     *             e.printStackTrace();
     *         }
     *     }
     *     static void a() throws HighLevelException {
     *         try {
     *             b();
     *         } catch(MidLevelException e) {
     *             throw new HighLevelException(e);
     *         }
     *     }
     *     static void b() throws MidLevelException {
     *         c();
     *     }   
     *     static void c() throws MidLevelException {
     *         try {
     *             d();
     *         } catch(LowLevelException e) {
     *             throw new MidLevelException(e);
     *         }
     *     }
     *     static void d() throws LowLevelException { 
     *        e();
     *     }
     *     static void e() throws LowLevelException {
     *         throw new LowLevelException();
     *     }
     * }
     *
     * class HighLevelException extends Exception {
     *     HighLevelException(Throwable cause) { super(cause); }
     * }
     *
     * class MidLevelException extends Exception {
     *     MidLevelException(Throwable cause)  { super(cause); }
     * }
     * 
     * class LowLevelException extends Exception {
     * }
     * </pre>
     */
    public void printStackTrace() { 
        printStackTrace(System.err);
    }

    /**
     * Prints this throwable and its backtrace to the specified print stream.
     *
     * @param s <code>PrintStream</code> to use for output
     */
    public void printStackTrace(PrintStream s) {
        synchronized (s) {
            s.println(this);

	    /* J2SE 1.3.* style printStackTrace()
              printStackTrace0(s); */

            StackTraceElement[] trace = getOurStackTrace();
            for (int i=0; i < trace.length; i++)
                s.println("\tat " + trace[i]);

            Throwable ourCause = getCause();
            if (ourCause != null)
                ourCause.printStackTraceAsCause(s, trace);
        }
    }

    /* For J2SE 1.3.* style printStackTrace():
     * The given object must have a void println(char[]) method.
     *
     * private native void printStackTrace0(Object s); 
     */

    /**
     * Print our stack trace as a cause for the specified stack trace.
     */
    private void printStackTraceAsCause(PrintStream s,
                                        StackTraceElement[] causedTrace)
    {
        // assert Thread.holdsLock(s);

        // Compute number of frames in common between this and caused
        StackTraceElement[] trace = getOurStackTrace();
        int m = trace.length-1, n = causedTrace.length-1;
        while (m >= 0 && n >=0 && trace[m].equals(causedTrace[n])) {
            m--; n--;
        }
        int framesInCommon = trace.length - 1 - m;

        s.println("Caused by: " + this);
        for (int i=0; i <= m; i++)
            s.println("\tat " + trace[i]);
        if (framesInCommon != 0)
            s.println("\t... " + framesInCommon + " more");

        // Recurse if we have a cause
        Throwable ourCause = getCause();
        if (ourCause != null)
            ourCause.printStackTraceAsCause(s, trace);
    }

    /**
     * Prints this throwable and its backtrace to the specified
     * print writer.
     *
     * @param s <code>PrintWriter</code> to use for output
     * @since   JDK1.1
     */
    public void printStackTrace(PrintWriter s) { 
        synchronized (s) {
            s.println(this);
            StackTraceElement[] trace = getOurStackTrace();
            for (int i=0; i < trace.length; i++)
                s.println("\tat " + trace[i]);

            Throwable ourCause = getCause();
            if (ourCause != null)
                ourCause.printStackTraceAsCause(s, trace);
        }
    }

    /**
     * Print our stack trace as a cause for the specified stack trace.
     */
    private void printStackTraceAsCause(PrintWriter s,
                                        StackTraceElement[] causedTrace)
    {
        // assert Thread.holdsLock(s);

        // Compute number of frames in common between this and caused
        StackTraceElement[] trace = getOurStackTrace();
        int m = trace.length-1, n = causedTrace.length-1;
        while (m >= 0 && n >=0 && trace[m].equals(causedTrace[n])) {
            m--; n--;
        }
        int framesInCommon = trace.length - 1 - m;

        s.println("Caused by: " + this);
        for (int i=0; i <= m; i++)
            s.println("\tat " + trace[i]);
        if (framesInCommon != 0)
            s.println("\t... " + framesInCommon + " more");

        // Recurse if we have a cause
        Throwable ourCause = getCause();
        if (ourCause != null)
            ourCause.printStackTraceAsCause(s, trace);
    }

    /**
     * Fills in the execution stack trace. This method records within this 
     * <code>Throwable</code> object information about the current state of 
     * the stack frames for the current thread.
     *
     * @return  a reference to this <code>Throwable</code> instance.
     * @see     java.lang.Throwable#printStackTrace()
     */
    public synchronized native Throwable fillInStackTrace();

    /**
     * Provides programmatic access to the stack trace information printed by
     * {@link #printStackTrace()}.  Returns an array of stack trace elements,
     * each representing one stack frame.  The zeroth element of the array
     * (assuming the array's length is non-zero) represents the top of the
     * stack, which is the last method invocation in the sequence.  Typically,
     * this is the point at which this throwable was created and thrown.
     * The last element of the array (assuming the array's length is non-zero)
     * represents the bottom of the stack, which is the first method invocation
     * in the sequence.
     *
     * <p>Some virtual machines may, under some circumstances, omit one
     * or more stack frames from the stack trace.  In the extreme case,
     * a virtual machine that has no stack trace information concerning
     * this throwable is permitted to return a zero-length array from this
     * method.  Generally speaking, the array returned by this method will
     * contain one element for every frame that would be printed by
     * <tt>printStackTrace</tt>.
     *
     * @return an array of stack trace elements representing the stack trace
     *         pertaining to this throwable.
     * @since  1.4
     */
    public StackTraceElement[] getStackTrace() {
        return (StackTraceElement[]) getOurStackTrace().clone();
    }

    private synchronized StackTraceElement[] getOurStackTrace() {
        // Initialize stack trace if this is the first call to this method
        if (stackTrace == null) {
            int depth = getStackTraceDepth();
            stackTrace = new StackTraceElement[depth];
            for (int i=0; i < depth; i++)
                stackTrace[i] = getStackTraceElement(i);
        }
        return stackTrace;
    }

    /**
     * Sets the stack trace elements that will be returned by
     * {@link #getStackTrace()} and printed by {@link #printStackTrace()}
     * and related methods.
     *
     * This method, which is designed for use by RPC frameworks and other
     * advanced systems, allows the client to override the default
     * stack trace that is either generated by {@link #fillInStackTrace()}
     * when a throwable is constructed or deserialized when a throwable is
     * read from a serialization stream.
     *
     * @param   stackTrace the stack trace elements to be associated with
     * this <code>Throwable</code>.  The specified array is copied by this
     * call; changes in the specified array after the method invocation
     * returns will have no affect on this <code>Throwable</code>'s stack
     * trace.
     *
     * @throws NullPointerException if <code>stackTrace</code> is
     *         <code>null</code>, or if any of the elements of
     *         <code>stackTrace</code> are <code>null</code>
     *
     * @since  1.4
     */
    public void setStackTrace(StackTraceElement[] stackTrace) {
        StackTraceElement[] defensiveCopy =
            (StackTraceElement[]) stackTrace.clone();
        for (int i = 0; i < defensiveCopy.length; i++)
            if (defensiveCopy[i] == null)
                throw new NullPointerException("stackTrace[" + i + "]");

        this.stackTrace = defensiveCopy;
    }

    /**
     * Returns the number of elements in the stack trace (or 0 if the stack
     * trace is unavailable).
     */
    private native int getStackTraceDepth();

    /**
     * Returns the specified element of the stack trace.
     *
     * @param index index of the element to return.
     * @throws IndexOutOfBoundsException if <tt>index %lt; 0 ||
     *         index &gt;= getStackTraceDepth() </tt>
     */
    private native StackTraceElement getStackTraceElement(int index);

    private synchronized void writeObject(java.io.ObjectOutputStream s)
        throws IOException
    {
        getOurStackTrace();  // Ensure that stackTrace field is initialized.
        s.defaultWriteObject();
    }
}