J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2004 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package java.lang; |
| 27 | |
| 28 | /** |
| 29 | * An element in a stack trace, as returned by {@link |
| 30 | * Throwable#getStackTrace()}. Each element represents a single stack frame. |
| 31 | * All stack frames except for the one at the top of the stack represent |
| 32 | * a method invocation. The frame at the top of the stack represents the |
| 33 | * execution point at which the stack trace was generated. Typically, |
| 34 | * this is the point at which the throwable corresponding to the stack trace |
| 35 | * was created. |
| 36 | * |
| 37 | * @since 1.4 |
| 38 | * @author Josh Bloch |
| 39 | */ |
| 40 | public final class StackTraceElement implements java.io.Serializable { |
| 41 | // Normally initialized by VM (public constructor added in 1.5) |
| 42 | private String declaringClass; |
| 43 | private String methodName; |
| 44 | private String fileName; |
| 45 | private int lineNumber; |
| 46 | |
| 47 | /** |
| 48 | * Creates a stack trace element representing the specified execution |
| 49 | * point. |
| 50 | * |
| 51 | * @param declaringClass the fully qualified name of the class containing |
| 52 | * the execution point represented by the stack trace element |
| 53 | * @param methodName the name of the method containing the execution point |
| 54 | * represented by the stack trace element |
| 55 | * @param fileName the name of the file containing the execution point |
| 56 | * represented by the stack trace element, or <tt>null</tt> if |
| 57 | * this information is unavailable |
| 58 | * @param lineNumber the line number of the source line containing the |
| 59 | * execution point represented by this stack trace element, or |
| 60 | * a negative number if this information is unavailable. A value |
| 61 | * of -2 indicates that the method containing the execution point |
| 62 | * is a native method |
| 63 | * @throws NullPointerException if <tt>declaringClass</tt> or |
| 64 | * <tt>methodName</tt> is null |
| 65 | * @since 1.5 |
| 66 | */ |
| 67 | public StackTraceElement(String declaringClass, String methodName, |
| 68 | String fileName, int lineNumber) { |
| 69 | if (declaringClass == null) |
| 70 | throw new NullPointerException("Declaring class is null"); |
| 71 | if (methodName == null) |
| 72 | throw new NullPointerException("Method name is null"); |
| 73 | |
| 74 | this.declaringClass = declaringClass; |
| 75 | this.methodName = methodName; |
| 76 | this.fileName = fileName; |
| 77 | this.lineNumber = lineNumber; |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Returns the name of the source file containing the execution point |
| 82 | * represented by this stack trace element. Generally, this corresponds |
| 83 | * to the <tt>SourceFile</tt> attribute of the relevant <tt>class</tt> |
| 84 | * file (as per <i>The Java Virtual Machine Specification</i>, Section |
| 85 | * 4.7.7). In some systems, the name may refer to some source code unit |
| 86 | * other than a file, such as an entry in source repository. |
| 87 | * |
| 88 | * @return the name of the file containing the execution point |
| 89 | * represented by this stack trace element, or <tt>null</tt> if |
| 90 | * this information is unavailable. |
| 91 | */ |
| 92 | public String getFileName() { |
| 93 | return fileName; |
| 94 | } |
| 95 | |
| 96 | /** |
| 97 | * Returns the line number of the source line containing the execution |
| 98 | * point represented by this stack trace element. Generally, this is |
| 99 | * derived from the <tt>LineNumberTable</tt> attribute of the relevant |
| 100 | * <tt>class</tt> file (as per <i>The Java Virtual Machine |
| 101 | * Specification</i>, Section 4.7.8). |
| 102 | * |
| 103 | * @return the line number of the source line containing the execution |
| 104 | * point represented by this stack trace element, or a negative |
| 105 | * number if this information is unavailable. |
| 106 | */ |
| 107 | public int getLineNumber() { |
| 108 | return lineNumber; |
| 109 | } |
| 110 | |
| 111 | /** |
| 112 | * Returns the fully qualified name of the class containing the |
| 113 | * execution point represented by this stack trace element. |
| 114 | * |
| 115 | * @return the fully qualified name of the <tt>Class</tt> containing |
| 116 | * the execution point represented by this stack trace element. |
| 117 | */ |
| 118 | public String getClassName() { |
| 119 | return declaringClass; |
| 120 | } |
| 121 | |
| 122 | /** |
| 123 | * Returns the name of the method containing the execution point |
| 124 | * represented by this stack trace element. If the execution point is |
| 125 | * contained in an instance or class initializer, this method will return |
| 126 | * the appropriate <i>special method name</i>, <tt><init></tt> or |
| 127 | * <tt><clinit></tt>, as per Section 3.9 of <i>The Java Virtual |
| 128 | * Machine Specification</i>. |
| 129 | * |
| 130 | * @return the name of the method containing the execution point |
| 131 | * represented by this stack trace element. |
| 132 | */ |
| 133 | public String getMethodName() { |
| 134 | return methodName; |
| 135 | } |
| 136 | |
| 137 | /** |
| 138 | * Returns true if the method containing the execution point |
| 139 | * represented by this stack trace element is a native method. |
| 140 | * |
| 141 | * @return <tt>true</tt> if the method containing the execution point |
| 142 | * represented by this stack trace element is a native method. |
| 143 | */ |
| 144 | public boolean isNativeMethod() { |
| 145 | return lineNumber == -2; |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * Returns a string representation of this stack trace element. The |
| 150 | * format of this string depends on the implementation, but the following |
| 151 | * examples may be regarded as typical: |
| 152 | * <ul> |
| 153 | * <li> |
| 154 | * <tt>"MyClass.mash(MyClass.java:9)"</tt> - Here, <tt>"MyClass"</tt> |
| 155 | * is the <i>fully-qualified name</i> of the class containing the |
| 156 | * execution point represented by this stack trace element, |
| 157 | * <tt>"mash"</tt> is the name of the method containing the execution |
| 158 | * point, <tt>"MyClass.java"</tt> is the source file containing the |
| 159 | * execution point, and <tt>"9"</tt> is the line number of the source |
| 160 | * line containing the execution point. |
| 161 | * <li> |
| 162 | * <tt>"MyClass.mash(MyClass.java)"</tt> - As above, but the line |
| 163 | * number is unavailable. |
| 164 | * <li> |
| 165 | * <tt>"MyClass.mash(Unknown Source)"</tt> - As above, but neither |
| 166 | * the file name nor the line number are available. |
| 167 | * <li> |
| 168 | * <tt>"MyClass.mash(Native Method)"</tt> - As above, but neither |
| 169 | * the file name nor the line number are available, and the method |
| 170 | * containing the execution point is known to be a native method. |
| 171 | * </ul> |
| 172 | * @see Throwable#printStackTrace() |
| 173 | */ |
| 174 | public String toString() { |
| 175 | return getClassName() + "." + methodName + |
| 176 | (isNativeMethod() ? "(Native Method)" : |
| 177 | (fileName != null && lineNumber >= 0 ? |
| 178 | "(" + fileName + ":" + lineNumber + ")" : |
| 179 | (fileName != null ? "("+fileName+")" : "(Unknown Source)"))); |
| 180 | } |
| 181 | |
| 182 | /** |
| 183 | * Returns true if the specified object is another |
| 184 | * <tt>StackTraceElement</tt> instance representing the same execution |
| 185 | * point as this instance. Two stack trace elements <tt>a</tt> and |
| 186 | * <tt>b</tt> are equal if and only if: |
| 187 | * <pre> |
| 188 | * equals(a.getFileName(), b.getFileName()) && |
| 189 | * a.getLineNumber() == b.getLineNumber()) && |
| 190 | * equals(a.getClassName(), b.getClassName()) && |
| 191 | * equals(a.getMethodName(), b.getMethodName()) |
| 192 | * </pre> |
| 193 | * where <tt>equals</tt> is defined as: |
| 194 | * <pre> |
| 195 | * static boolean equals(Object a, Object b) { |
| 196 | * return a==b || (a != null && a.equals(b)); |
| 197 | * } |
| 198 | * </pre> |
| 199 | * |
| 200 | * @param obj the object to be compared with this stack trace element. |
| 201 | * @return true if the specified object is another |
| 202 | * <tt>StackTraceElement</tt> instance representing the same |
| 203 | * execution point as this instance. |
| 204 | */ |
| 205 | public boolean equals(Object obj) { |
| 206 | if (obj==this) |
| 207 | return true; |
| 208 | if (!(obj instanceof StackTraceElement)) |
| 209 | return false; |
| 210 | StackTraceElement e = (StackTraceElement)obj; |
| 211 | return e.declaringClass.equals(declaringClass) && e.lineNumber == lineNumber |
| 212 | && eq(methodName, e.methodName) && eq(fileName, e.fileName); |
| 213 | } |
| 214 | |
| 215 | private static boolean eq(Object a, Object b) { |
| 216 | return a==b || (a != null && a.equals(b)); |
| 217 | } |
| 218 | |
| 219 | /** |
| 220 | * Returns a hash code value for this stack trace element. |
| 221 | */ |
| 222 | public int hashCode() { |
| 223 | int result = 31*declaringClass.hashCode() + methodName.hashCode(); |
| 224 | result = 31*result + (fileName == null ? 0 : fileName.hashCode()); |
| 225 | result = 31*result + lineNumber; |
| 226 | return result; |
| 227 | } |
| 228 | |
| 229 | private static final long serialVersionUID = 6992337162326171013L; |
| 230 | } |