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	/*
	* 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;
	}

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