java.lang.StackTraceElement Maven / Gradle / Ivy
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package java.lang;
/**
* 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= declaringClass;
this.methodName= methodName;
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 The Java Virtual Machine Specification, 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 The Java Virtual Machine
* Specification, 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 special method name, {@code } or
* {@code }, as per Section 3.9 of The Java Virtual
* Machine Specification.
*
* @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:
*
* -
* {@code "MyClass.mash(MyClass.java:9)"} - Here, {@code "MyClass"}
* is the fully-qualified name 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.
*
-
* {@code "MyClass.mash(MyClass.java)"} - As above, but the line
* number is unavailable.
*
-
* {@code "MyClass.mash(Unknown Source)"} - As above, but neither
* the file name nor the line number are available.
*
-
* {@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.
*
* @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:
*
* equals(a.getFileName(), b.getFileName()) &&
* a.getLineNumber() == b.getLineNumber()) &&
* equals(a.getClassName(), b.getClassName()) &&
* equals(a.getMethodName(), b.getMethodName())
*
* 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 false;
}
/**
* Returns a hash code value for this stack trace element.
*/
public int hashCode()
{
return 0;
}
private static final long serialVersionUID= 6992337162326171013L;
}
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