Vector listIterator() method in Java with Examples
Last Updated :
02 Jan, 2019
java.util.Vector.listIterator()
This method returns a list iterator over the elements of a
Vector object in proper sequence. It is bidirectional, so both forward and backward traversal is possible, using
next() and
previous() respectively. The iterator thus returned is
fail-fast. This means that structurally modifying the vector after the iterator is created, in any way except through the
iterator's own remove or add methods (using
Vector.add(), for example), will cause iterator to throw
ConcurrentModificationException.
Syntax:
public ListIterator listIterator()
Parameters: This method accepts no input arguments.
Return Value: This method returns a
ListIterator object which can be used to traverse the Vector object.
Example 1: To demonstrate forward and backward traversal using listIterator().
Java
// Java code to illustrate listIterator()
import java.util.Vector;
import java.util.ListIterator;
public class GFG {
public static void main(String[] args)
{
// Declare empty vector
Vector<String> vt = new Vector<String>();
vt.add("Geeks");
vt.add("for");
vt.add("Geeks");
vt.add("2019");
vt.add("AComputerSciencePortalForGeeks");
// Declare list iterator
ListIterator listItr = vt.listIterator();
// Forward iterations
System.out.println("Forward Traversal:");
while (listItr.hasNext()) {
System.out.println(listItr.next());
}
// Backward iterations
System.out.println("\nBackward Traversal:");
while (listItr.hasPrevious()) {
System.out.println(listItr.previous());
}
}
}
Output:
Forward Traversal:
Geeks
for
Geeks
2019
AComputerSciencePortalForGeeks
Backward Traversal:
AComputerSciencePortalForGeeks
2019
Geeks
for
Geeks
java.util.Vector.listIterator(int index)
This method is used to return a list iterator by specifying starting index. Also bidirectional and fail-fast.
Syntax:
public ListIterator listIterator(int index)
Parameters: The parameter index is an integer type value that specifies the first element to be returned from the list iterator (by a call to
next()).
Return Value: This method returns a
ListIterator object which can be used to traverse the Vector object.
Exception: This method throws
IndexOutOfBoundsException, if the index is out of range (index < 0 or index > size())
Example 2: To demonstrate listIterator(int index).
Java
// Java code to illustrate listIterator(int index)
import java.util.Vector;
import java.util.ListIterator;
public class GFG {
public static void main(String[] args)
{
// Declare empty vector
Vector<String> vt = new Vector<String>();
vt.add("Geeks");
vt.add("for");
vt.add("Geeks");
// Declare list iterator
ListIterator listItr = vt.listIterator(1);
// traversal
while (listItr.hasNext()) {
System.out.println(listItr.next());
}
}
}
To demonstrate
IndexOutOfBoundsException thrown by listIterator(int index).
Java
// Java code to illustrate IndexOutOfBoundsException
// thrown by listIterator(int index)
import java.util.Vector;
import java.util.ListIterator;
public class GFG {
public static void main(String[] args)
{
// Declare empty vector
Vector<String> vt
= new Vector<String>();
vt.add("Geeks");
vt.add("for");
vt.add("Geeks");
// Declare list iterator at starting
// index greater than vector size
try {
ListIterator listItr
= vt.listIterator(5);
}
catch (IndexOutOfBoundsException e) {
// Exception handling
System.out.println("Exception: " + e);
}
}
}
Output:
Exception: java.lang.IndexOutOfBoundsException: Index: 5
Example 4: To demonstrate
ConcurrentModificationException thrown by ListIterator object when Vector object is modified after creating list iterator to it.
Java
// Java code to illustrate ConcurrentModificationException
// thrown by ListIterator object
import java.util.ConcurrentModificationException;
import java.util.Vector;
import java.util.ListIterator;
public class GFG {
public static void main(String[] args)
{
// Declare empty vector
Vector<String> vt = new Vector<String>();
vt.add("Geeks");
vt.add("for");
// Declare list iterator
ListIterator listItr = vt.listIterator();
// modify vector after creating list iterator
vt.add("Geeks");
try {
// Exception thrown here
System.out.println(listItr.next());
}
catch (ConcurrentModificationException e) {
// Exception handling
System.out.println("Exception: " + e);
}
}
}
Output:
Exception: java.util.ConcurrentModificationException
Reference:
https://docs.oracle.com/javase/8/docs/api/java/util/Vector.html#listIterator--