jdk/src/java.base/share/classes/java/lang/StackTraceElement.java
changeset 25859 3317bb8137f4
parent 23010 6dadb192ad81
child 36511 9d0388c6b336
child 37313 b0c043d9ad18
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/src/java.base/share/classes/java/lang/StackTraceElement.java	Sun Aug 17 15:54:13 2014 +0100
@@ -0,0 +1,221 @@
+/*
+ * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package java.lang;
+
+import java.util.Objects;
+
+/**
+ * An element in a stack trace, as returned by {@link
+ * Throwable#getStackTrace()}.  Each element represents a single stack frame.
+ * All stack frames except for the one at the top of the stack represent
+ * a method invocation.  The frame at the top of the stack represents the
+ * execution point at which the stack trace was generated.  Typically,
+ * this is the point at which the throwable corresponding to the stack trace
+ * was created.
+ *
+ * @since  1.4
+ * @author Josh Bloch
+ */
+public final class StackTraceElement implements java.io.Serializable {
+    // Normally initialized by VM (public constructor added in 1.5)
+    private String declaringClass;
+    private String methodName;
+    private String fileName;
+    private int    lineNumber;
+
+    /**
+     * Creates a stack trace element representing the specified execution
+     * point.
+     *
+     * @param declaringClass the fully qualified name of the class containing
+     *        the execution point represented by the stack trace element
+     * @param methodName the name of the method containing the execution point
+     *        represented by the stack trace element
+     * @param fileName the name of the file containing the execution point
+     *         represented by the stack trace element, or {@code null} if
+     *         this information is unavailable
+     * @param lineNumber the line number of the source line containing the
+     *         execution point represented by this stack trace element, or
+     *         a negative number if this information is unavailable. A value
+     *         of -2 indicates that the method containing the execution point
+     *         is a native method
+     * @throws NullPointerException if {@code declaringClass} or
+     *         {@code methodName} is null
+     * @since 1.5
+     */
+    public StackTraceElement(String declaringClass, String methodName,
+                             String fileName, int lineNumber) {
+        this.declaringClass = Objects.requireNonNull(declaringClass, "Declaring class is null");
+        this.methodName     = Objects.requireNonNull(methodName, "Method name is null");
+        this.fileName       = fileName;
+        this.lineNumber     = lineNumber;
+    }
+
+    /**
+     * Returns the name of the source file containing the execution point
+     * represented by this stack trace element.  Generally, this corresponds
+     * to the {@code SourceFile} attribute of the relevant {@code class}
+     * file (as per <i>The Java Virtual Machine Specification</i>, Section
+     * 4.7.7).  In some systems, the name may refer to some source code unit
+     * other than a file, such as an entry in source repository.
+     *
+     * @return the name of the file containing the execution point
+     *         represented by this stack trace element, or {@code null} if
+     *         this information is unavailable.
+     */
+    public String getFileName() {
+        return fileName;
+    }
+
+    /**
+     * Returns the line number of the source line containing the execution
+     * point represented by this stack trace element.  Generally, this is
+     * derived from the {@code LineNumberTable} attribute of the relevant
+     * {@code class} file (as per <i>The Java Virtual Machine
+     * Specification</i>, Section 4.7.8).
+     *
+     * @return the line number of the source line containing the execution
+     *         point represented by this stack trace element, or a negative
+     *         number if this information is unavailable.
+     */
+    public int getLineNumber() {
+        return lineNumber;
+    }
+
+    /**
+     * Returns the fully qualified name of the class containing the
+     * execution point represented by this stack trace element.
+     *
+     * @return the fully qualified name of the {@code Class} containing
+     *         the execution point represented by this stack trace element.
+     */
+    public String getClassName() {
+        return declaringClass;
+    }
+
+    /**
+     * Returns the name of the method containing the execution point
+     * represented by this stack trace element.  If the execution point is
+     * contained in an instance or class initializer, this method will return
+     * the appropriate <i>special method name</i>, {@code <init>} or
+     * {@code <clinit>}, as per Section 3.9 of <i>The Java Virtual
+     * Machine Specification</i>.
+     *
+     * @return the name of the method containing the execution point
+     *         represented by this stack trace element.
+     */
+    public String getMethodName() {
+        return methodName;
+    }
+
+    /**
+     * Returns true if the method containing the execution point
+     * represented by this stack trace element is a native method.
+     *
+     * @return {@code true} if the method containing the execution point
+     *         represented by this stack trace element is a native method.
+     */
+    public boolean isNativeMethod() {
+        return lineNumber == -2;
+    }
+
+    /**
+     * Returns a string representation of this stack trace element.  The
+     * format of this string depends on the implementation, but the following
+     * examples may be regarded as typical:
+     * <ul>
+     * <li>
+     *   {@code "MyClass.mash(MyClass.java:9)"} - Here, {@code "MyClass"}
+     *   is the <i>fully-qualified name</i> of the class containing the
+     *   execution point represented by this stack trace element,
+     *   {@code "mash"} is the name of the method containing the execution
+     *   point, {@code "MyClass.java"} is the source file containing the
+     *   execution point, and {@code "9"} is the line number of the source
+     *   line containing the execution point.
+     * <li>
+     *   {@code "MyClass.mash(MyClass.java)"} - As above, but the line
+     *   number is unavailable.
+     * <li>
+     *   {@code "MyClass.mash(Unknown Source)"} - As above, but neither
+     *   the file name nor the line  number are available.
+     * <li>
+     *   {@code "MyClass.mash(Native Method)"} - As above, but neither
+     *   the file name nor the line  number are available, and the method
+     *   containing the execution point is known to be a native method.
+     * </ul>
+     * @see    Throwable#printStackTrace()
+     */
+    public String toString() {
+        return getClassName() + "." + methodName +
+            (isNativeMethod() ? "(Native Method)" :
+             (fileName != null && lineNumber >= 0 ?
+              "(" + fileName + ":" + lineNumber + ")" :
+              (fileName != null ?  "("+fileName+")" : "(Unknown Source)")));
+    }
+
+    /**
+     * Returns true if the specified object is another
+     * {@code StackTraceElement} instance representing the same execution
+     * point as this instance.  Two stack trace elements {@code a} and
+     * {@code b} are equal if and only if:
+     * <pre>{@code
+     *     equals(a.getFileName(), b.getFileName()) &&
+     *     a.getLineNumber() == b.getLineNumber()) &&
+     *     equals(a.getClassName(), b.getClassName()) &&
+     *     equals(a.getMethodName(), b.getMethodName())
+     * }</pre>
+     * where {@code equals} has the semantics of {@link
+     * java.util.Objects#equals(Object, Object) Objects.equals}.
+     *
+     * @param  obj the object to be compared with this stack trace element.
+     * @return true if the specified object is another
+     *         {@code StackTraceElement} instance representing the same
+     *         execution point as this instance.
+     */
+    public boolean equals(Object obj) {
+        if (obj==this)
+            return true;
+        if (!(obj instanceof StackTraceElement))
+            return false;
+        StackTraceElement e = (StackTraceElement)obj;
+        return e.declaringClass.equals(declaringClass) &&
+            e.lineNumber == lineNumber &&
+            Objects.equals(methodName, e.methodName) &&
+            Objects.equals(fileName, e.fileName);
+    }
+
+    /**
+     * Returns a hash code value for this stack trace element.
+     */
+    public int hashCode() {
+        int result = 31*declaringClass.hashCode() + methodName.hashCode();
+        result = 31*result + Objects.hashCode(fileName);
+        result = 31*result + lineNumber;
+        return result;
+    }
+
+    private static final long serialVersionUID = 6992337162326171013L;
+}