Class java.util.Vector
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Class java.util.Vector
java.lang.Object
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+----java.util.Vector
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public class
Vector
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extends Object
Vector class (a growable array).
Each vector tries to optimize storage management by maintaining
a capacity and a capacityIncrement. The capacity is always at
least as large as the vector size; it is usually larger because
as elements are added to the vector, the vector's
storage increases in chunks the size of capacityIncrement. Setting
the capacity to what you want before inserting a large number of
objects will reduce the amount of incremental reallocation.
You can safely ignore the capacity and the vector will still work
correctly.
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Version:
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1.27, 08/18/95
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Author:
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Jonathan Payne,
Lee Boynton
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capacityIncrement
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The size of the increment.
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elementCount
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The number of elements in the buffer.
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elementData
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The buffer where elements are stored.
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Vector(int, int)
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Constructs an empty vector with the specified storage
capacity and the specified capacityIncrement.
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Vector(int)
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Constructs an empty vector with the specified storage capacity.
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Vector()
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Constructs an empty vector.
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addElement(Object)
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Adds the specified object as the last element of the vector.
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capacity()
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Returns the current capacity of the vector.
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clone()
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Clones this vector.
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contains(Object)
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Returns true if the specified object is a value of the
collection.
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copyInto(Object[])
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Copies the elements of this vector into the specified array.
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elementAt(int)
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Returns the element at the specified index.
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elements()
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Returns an enumeration of the elements.
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ensureCapacity(int)
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Ensures that the vector has at least the specified capacity.
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firstElement()
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Returns the first element of the sequence.
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indexOf(Object)
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Searches for the specified object, starting from the first position
and returns an index to it.
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indexOf(Object, int)
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Searches for the specified object, starting at the specified
position and returns an index to it.
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insertElementAt(Object, int)
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Inserts the specified object as an element at the specified index.
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isEmpty()
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Returns true if the collection contains no values.
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lastElement()
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Returns the last element of the sequence.
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lastIndexOf(Object)
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Searches backwards for the specified object, starting from the last
position and returns an index to it.
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lastIndexOf(Object, int)
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Searches backwards for the specified object, starting from the specified
position and returns an index to it.
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removeAllElements()
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Removes all elements of the vector.
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removeElement(Object)
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Removes the element from the vector.
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removeElementAt(int)
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Deletes the element at the specified index.
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setElementAt(Object, int)
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Sets the element at the specified index to be the specified object.
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setSize(int)
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Sets the size of the vector.
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size()
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Returns the number of elements in the vector.
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toString()
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Converts the vector to a string.
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trimToSize()
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Trims the vector's capacity down to size.
elementData
protected Object elementData[]
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The buffer where elements are stored.
elementCount
protected int elementCount
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The number of elements in the buffer.
capacityIncrement
protected int capacityIncrement
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The size of the increment. If it is 0 the size of the
the buffer is doubled everytime it needs to grow.
Vector
public Vector(int initialCapacity,
int capacityIncrement)
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Constructs an empty vector with the specified storage
capacity and the specified capacityIncrement.
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Parameters:
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initialCapacity
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the initial storage capacity of the vector
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capacityIncrement
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how much to increase the element's
size by.
Vector
public Vector(int initialCapacity)
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Constructs an empty vector with the specified storage capacity.
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Parameters:
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initialCapacity
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the initial storage capacity of the vector
Vector
public Vector()
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Constructs an empty vector.
copyInto
public final synchronized void copyInto(Object anArray[])
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Copies the elements of this vector into the specified array.
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Parameters:
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anArray
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the array where elements get copied into
trimToSize
public final synchronized void trimToSize()
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Trims the vector's capacity down to size. Use this operation to
minimize the storage of a vector. Subsequent insertions will
cause reallocation.
ensureCapacity
public final synchronized void ensureCapacity(int minCapacity)
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Ensures that the vector has at least the specified capacity.
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Parameters:
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minCapacity
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the desired minimum capacity
setSize
public final synchronized void setSize(int newSize)
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Sets the size of the vector. If the size shrinks, the extra elements
(at the end of the vector) are lost; if the size increases, the
new elements are set to null.
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Parameters:
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newSize
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the new size of the vector
capacity
public final int capacity()
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Returns the current capacity of the vector.
size
public final int size()
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Returns the number of elements in the vector.
Note that this is not the same as the vector's capacity.
isEmpty
public final boolean isEmpty()
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Returns true if the collection contains no values.
elements
public final synchronized Enumeration elements()
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Returns an enumeration of the elements. Use the Enumeration methods on
the returned object to fetch the elements sequentially.
contains
public final boolean contains(Object elem)
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Returns true if the specified object is a value of the
collection.
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Parameters:
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elem
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the desired element
indexOf
public final int indexOf(Object elem)
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Searches for the specified object, starting from the first position
and returns an index to it.
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Parameters:
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elem
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the desired element
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Returns:
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the index of the element, or -1 if it was not found.
indexOf
public final synchronized int indexOf(Object elem,
int index)
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Searches for the specified object, starting at the specified
position and returns an index to it.
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Parameters:
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elem
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the desired element
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index
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the index where to start searching
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Returns:
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the index of the element, or -1 if it was not found.
lastIndexOf
public final int lastIndexOf(Object elem)
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Searches backwards for the specified object, starting from the last
position and returns an index to it.
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Parameters:
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elem
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the desired element
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Returns:
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the index of the element, or -1 if it was not found.
lastIndexOf
public final synchronized int lastIndexOf(Object elem,
int index)
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Searches backwards for the specified object, starting from the specified
position and returns an index to it.
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Parameters:
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elem
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the desired element
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index
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the index where to start searching
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Returns:
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the index of the element, or -1 if it was not found.
elementAt
public final synchronized Object elementAt(int index)
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Returns the element at the specified index.
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Parameters:
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index
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the index of the desired element
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Throws: ArrayIndexOutOfBoundsException
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If an invalid
index was given.
firstElement
public final synchronized Object firstElement()
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Returns the first element of the sequence.
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Throws: NoSuchElementException
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If the sequence is empty.
lastElement
public final synchronized Object lastElement()
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Returns the last element of the sequence.
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Throws: NoSuchElementException
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If the sequence is empty.
setElementAt
public final synchronized void setElementAt(Object obj,
int index)
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Sets the element at the specified index to be the specified object.
The previous element at that position is discarded.
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Parameters:
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obj
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what the element is to be set to
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index
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the specified index
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Throws: ArrayIndexOutOfBoundsException
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If the index was
invalid.
removeElementAt
public final synchronized void removeElementAt(int index)
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Deletes the element at the specified index. Elements with an index
greater than the current index are moved down.
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Parameters:
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index
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the element to remove
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Throws: ArrayIndexOutOfBoundsException
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If the index was invalid.
insertElementAt
public final synchronized void insertElementAt(Object obj,
int index)
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Inserts the specified object as an element at the specified index.
Elements with an index greater or equal to the current index
are shifted up.
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Parameters:
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obj
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the element to insert
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index
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where to insert the new element
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Throws: ArrayIndexOutOfBoundsException
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If the index was invalid.
addElement
public final synchronized void addElement(Object obj)
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Adds the specified object as the last element of the vector.
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Parameters:
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obj
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the element to be added
removeElement
public final synchronized boolean removeElement(Object obj)
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Removes the element from the vector. If the object occurs more
than once, only the first is removed. If the object is not an
element, returns false.
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Parameters:
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obj
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the element to be removed
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Returns:
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true if the element was actually removed; false otherwise.
removeAllElements
public final synchronized void removeAllElements()
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Removes all elements of the vector. The vector becomes empty.
clone
public synchronized Object clone()
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Clones this vector. The elements are not cloned.
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Overrides:
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clone in class Object
toString
public final synchronized String toString()
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Converts the vector to a string. Useful for debugging.
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Overrides:
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toString in class Object
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