jaroslav@52: /*
jaroslav@52:  * Copyright (c) 2000, 2011, Oracle and/or its affiliates. All rights reserved.
jaroslav@52:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jaroslav@52:  *
jaroslav@52:  * This code is free software; you can redistribute it and/or modify it
jaroslav@52:  * under the terms of the GNU General Public License version 2 only, as
jaroslav@52:  * published by the Free Software Foundation.  Oracle designates this
jaroslav@52:  * particular file as subject to the "Classpath" exception as provided
jaroslav@52:  * by Oracle in the LICENSE file that accompanied this code.
jaroslav@52:  *
jaroslav@52:  * This code is distributed in the hope that it will be useful, but WITHOUT
jaroslav@52:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jaroslav@52:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
jaroslav@52:  * version 2 for more details (a copy is included in the LICENSE file that
jaroslav@52:  * accompanied this code).
jaroslav@52:  *
jaroslav@52:  * You should have received a copy of the GNU General Public License version
jaroslav@52:  * 2 along with this work; if not, write to the Free Software Foundation,
jaroslav@52:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jaroslav@52:  *
jaroslav@52:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
jaroslav@52:  * or visit www.oracle.com if you need additional information or have any
jaroslav@52:  * questions.
jaroslav@52:  */
jaroslav@52: 
jaroslav@52: package java.lang;
jaroslav@52: 
jaroslav@52: /**
jaroslav@52:  * An element in a stack trace, as returned by {@link
jaroslav@52:  * Throwable#getStackTrace()}.  Each element represents a single stack frame.
jaroslav@52:  * All stack frames except for the one at the top of the stack represent
jaroslav@52:  * a method invocation.  The frame at the top of the stack represents the
jaroslav@52:  * execution point at which the stack trace was generated.  Typically,
jaroslav@52:  * this is the point at which the throwable corresponding to the stack trace
jaroslav@52:  * was created.
jaroslav@52:  *
jaroslav@52:  * @since  1.4
jaroslav@52:  * @author Josh Bloch
jaroslav@52:  */
jaroslav@52: public final class StackTraceElement implements java.io.Serializable {
jaroslav@52:     // Normally initialized by VM (public constructor added in 1.5)
jaroslav@52:     private String declaringClass;
jaroslav@52:     private String methodName;
jaroslav@52:     private String fileName;
jaroslav@52:     private int    lineNumber;
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Creates a stack trace element representing the specified execution
jaroslav@52:      * point.
jaroslav@52:      *
jaroslav@52:      * @param declaringClass the fully qualified name of the class containing
jaroslav@52:      *        the execution point represented by the stack trace element
jaroslav@52:      * @param methodName the name of the method containing the execution point
jaroslav@52:      *        represented by the stack trace element
jaroslav@52:      * @param fileName the name of the file containing the execution point
jaroslav@52:      *         represented by the stack trace element, or {@code null} if
jaroslav@52:      *         this information is unavailable
jaroslav@52:      * @param lineNumber the line number of the source line containing the
jaroslav@52:      *         execution point represented by this stack trace element, or
jaroslav@52:      *         a negative number if this information is unavailable. A value
jaroslav@52:      *         of -2 indicates that the method containing the execution point
jaroslav@52:      *         is a native method
jaroslav@52:      * @throws NullPointerException if {@code declaringClass} or
jaroslav@52:      *         {@code methodName} is null
jaroslav@52:      * @since 1.5
jaroslav@52:      */
jaroslav@52:     public StackTraceElement(String declaringClass, String methodName,
jaroslav@52:                              String fileName, int lineNumber) {
jaroslav@65:         this.declaringClass = declaringClass;
jaroslav@65:         this.methodName     = methodName;
jaroslav@52:         this.fileName       = fileName;
jaroslav@52:         this.lineNumber     = lineNumber;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns the name of the source file containing the execution point
jaroslav@52:      * represented by this stack trace element.  Generally, this corresponds
jaroslav@52:      * to the {@code SourceFile} attribute of the relevant {@code class}
jaroslav@52:      * file (as per <i>The Java Virtual Machine Specification</i>, Section
jaroslav@52:      * 4.7.7).  In some systems, the name may refer to some source code unit
jaroslav@52:      * other than a file, such as an entry in source repository.
jaroslav@52:      *
jaroslav@52:      * @return the name of the file containing the execution point
jaroslav@52:      *         represented by this stack trace element, or {@code null} if
jaroslav@52:      *         this information is unavailable.
jaroslav@52:      */
jaroslav@52:     public String getFileName() {
jaroslav@52:         return fileName;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns the line number of the source line containing the execution
jaroslav@52:      * point represented by this stack trace element.  Generally, this is
jaroslav@52:      * derived from the {@code LineNumberTable} attribute of the relevant
jaroslav@52:      * {@code class} file (as per <i>The Java Virtual Machine
jaroslav@52:      * Specification</i>, Section 4.7.8).
jaroslav@52:      *
jaroslav@52:      * @return the line number of the source line containing the execution
jaroslav@52:      *         point represented by this stack trace element, or a negative
jaroslav@52:      *         number if this information is unavailable.
jaroslav@52:      */
jaroslav@52:     public int getLineNumber() {
jaroslav@52:         return lineNumber;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns the fully qualified name of the class containing the
jaroslav@52:      * execution point represented by this stack trace element.
jaroslav@52:      *
jaroslav@52:      * @return the fully qualified name of the {@code Class} containing
jaroslav@52:      *         the execution point represented by this stack trace element.
jaroslav@52:      */
jaroslav@52:     public String getClassName() {
jaroslav@52:         return declaringClass;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns the name of the method containing the execution point
jaroslav@52:      * represented by this stack trace element.  If the execution point is
jaroslav@52:      * contained in an instance or class initializer, this method will return
jaroslav@52:      * the appropriate <i>special method name</i>, {@code <init>} or
jaroslav@52:      * {@code <clinit>}, as per Section 3.9 of <i>The Java Virtual
jaroslav@52:      * Machine Specification</i>.
jaroslav@52:      *
jaroslav@52:      * @return the name of the method containing the execution point
jaroslav@52:      *         represented by this stack trace element.
jaroslav@52:      */
jaroslav@52:     public String getMethodName() {
jaroslav@52:         return methodName;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns true if the method containing the execution point
jaroslav@52:      * represented by this stack trace element is a native method.
jaroslav@52:      *
jaroslav@52:      * @return {@code true} if the method containing the execution point
jaroslav@52:      *         represented by this stack trace element is a native method.
jaroslav@52:      */
jaroslav@52:     public boolean isNativeMethod() {
jaroslav@52:         return lineNumber == -2;
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns a string representation of this stack trace element.  The
jaroslav@52:      * format of this string depends on the implementation, but the following
jaroslav@52:      * examples may be regarded as typical:
jaroslav@52:      * <ul>
jaroslav@52:      * <li>
jaroslav@52:      *   {@code "MyClass.mash(MyClass.java:9)"} - Here, {@code "MyClass"}
jaroslav@52:      *   is the <i>fully-qualified name</i> of the class containing the
jaroslav@52:      *   execution point represented by this stack trace element,
jaroslav@52:      *   {@code "mash"} is the name of the method containing the execution
jaroslav@52:      *   point, {@code "MyClass.java"} is the source file containing the
jaroslav@52:      *   execution point, and {@code "9"} is the line number of the source
jaroslav@52:      *   line containing the execution point.
jaroslav@52:      * <li>
jaroslav@52:      *   {@code "MyClass.mash(MyClass.java)"} - As above, but the line
jaroslav@52:      *   number is unavailable.
jaroslav@52:      * <li>
jaroslav@52:      *   {@code "MyClass.mash(Unknown Source)"} - As above, but neither
jaroslav@52:      *   the file name nor the line  number are available.
jaroslav@52:      * <li>
jaroslav@52:      *   {@code "MyClass.mash(Native Method)"} - As above, but neither
jaroslav@52:      *   the file name nor the line  number are available, and the method
jaroslav@52:      *   containing the execution point is known to be a native method.
jaroslav@52:      * </ul>
jaroslav@52:      * @see    Throwable#printStackTrace()
jaroslav@52:      */
jaroslav@52:     public String toString() {
jaroslav@52:         return getClassName() + "." + methodName +
jaroslav@52:             (isNativeMethod() ? "(Native Method)" :
jaroslav@52:              (fileName != null && lineNumber >= 0 ?
jaroslav@52:               "(" + fileName + ":" + lineNumber + ")" :
jaroslav@52:               (fileName != null ?  "("+fileName+")" : "(Unknown Source)")));
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns true if the specified object is another
jaroslav@52:      * {@code StackTraceElement} instance representing the same execution
jaroslav@52:      * point as this instance.  Two stack trace elements {@code a} and
jaroslav@52:      * {@code b} are equal if and only if:
jaroslav@52:      * <pre>
jaroslav@52:      *     equals(a.getFileName(), b.getFileName()) &&
jaroslav@52:      *     a.getLineNumber() == b.getLineNumber()) &&
jaroslav@52:      *     equals(a.getClassName(), b.getClassName()) &&
jaroslav@52:      *     equals(a.getMethodName(), b.getMethodName())
jaroslav@52:      * </pre>
jaroslav@52:      * where {@code equals} has the semantics of {@link
jaroslav@52:      * java.util.Objects#equals(Object, Object) Objects.equals}.
jaroslav@52:      *
jaroslav@52:      * @param  obj the object to be compared with this stack trace element.
jaroslav@52:      * @return true if the specified object is another
jaroslav@52:      *         {@code StackTraceElement} instance representing the same
jaroslav@52:      *         execution point as this instance.
jaroslav@52:      */
jaroslav@52:     public boolean equals(Object obj) {
jaroslav@52:         if (obj==this)
jaroslav@52:             return true;
jaroslav@52:         if (!(obj instanceof StackTraceElement))
jaroslav@52:             return false;
jaroslav@52:         StackTraceElement e = (StackTraceElement)obj;
jaroslav@52:         return e.declaringClass.equals(declaringClass) &&
jaroslav@52:             e.lineNumber == lineNumber &&
jaroslav@65:             equals(methodName, e.methodName) &&
jaroslav@65:             equals(fileName, e.fileName);
jaroslav@52:     }
jaroslav@52: 
jaroslav@52:     /**
jaroslav@52:      * Returns a hash code value for this stack trace element.
jaroslav@52:      */
jaroslav@52:     public int hashCode() {
jaroslav@52:         int result = 31*declaringClass.hashCode() + methodName.hashCode();
jaroslav@65:         result = 31*result + (fileName == null ? 0 : fileName.hashCode());
jaroslav@52:         result = 31*result + lineNumber;
jaroslav@52:         return result;
jaroslav@52:     }
jaroslav@65:     
jaroslav@65:     private static boolean equals(Object a, Object b) {
jaroslav@65:         return (a == b) || (a != null && a.equals(b));
jaroslav@65:     }
jaroslav@52: 
jaroslav@52:     private static final long serialVersionUID = 6992337162326171013L;
jaroslav@52: }