CopyOnWriteArrayList listIterator() method in Java
The listIterator() method of CopyOnWriteArrayList returns an listIterator over the elements in this list in proper sequence. The listIterator does NOT support the remove, set or add methods.
Syntax:
public ListIterator listIterator()
Parameters: The function does not accept any parameters.
Return Value: The function returns a list iterator over the elements in this list (in proper sequence)
Below programs illustrate the above function:
Program 1:
Java
// Java Program to illustrate the CopyOnWriteArrayList // listIterator() method in Java import java.util.concurrent.CopyOnWriteArrayList; import java.util.*; public class GFG { public static void main(String[] args) { // create object of CopyOnWriteArrayList CopyOnWriteArrayList<Integer> ArrLis = new CopyOnWriteArrayList<Integer>(); // Add elements ArrLis.add( 32 ); ArrLis.add( 67 ); ArrLis.add( 67 ); ArrLis.add( 100 ); // print CopyOnWriteArrayList System.out.println( "CopyOnWriteArrayList: " + ArrLis); // Call listIterator() method of Iterator iteratorVals = ArrLis.listIterator(); // Print elements of iterator // created from CopyOnWriteArrayList System.out.println( "The iterator values" + " of CopyOnWriteArrayList are:" ); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
CopyOnWriteArrayList: [32, 67, 67, 100] The iterator values of CopyOnWriteArrayList are: 32 67 67 100
The listIterator(index) method of CopyOnWriteArrayList returns an listIterator over the elements in this list in proper sequence starting from a particular index. The listIterator does NOT support the remove, set or add methods.
Syntax:
public ListIterator listIterator(int index)
Parameters: The function accepts a parameter index which specifies the index of the first element to be returned from the list iterator.
Return Value: The function returns a list iterator over the elements in this list starting from the specified index (in proper sequence).
Exceptions: The function throws IndexOutOfBoundsException if the index is out of range.
Below programs illustrate the above function:
Program 1:
Java
// Java Program to illustrate the CopyOnWriteArrayList // listIterator() method in Java import java.util.concurrent.CopyOnWriteArrayList; import java.util.*; public class GFG { public static void main(String[] args) { // create object of CopyOnWriteArrayList CopyOnWriteArrayList<String> ArrLis = new CopyOnWriteArrayList<String>(); // Add elements ArrLis.add( "gopal" ); ArrLis.add( "gfg" ); ArrLis.add( "jgec" ); ArrLis.add( "sudo" ); // print CopyOnWriteArrayList System.out.println( "CopyOnWriteArrayList: " + ArrLis); // Call listIterator() method from 2nd index Iterator iteratorVals = ArrLis.listIterator( 2 ); // Print elements of iterator // created from CopyOnWriteArrayList System.out.println( "The iterator values" + " of CopyOnWriteArrayList are:" ); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
CopyOnWriteArrayList: [gopal, gfg, jgec, sudo] The iterator values of CopyOnWriteArrayList are: jgec sudo
Program 2:
Java
// Java Program to illustrate the CopyOnWriteArrayList // listIterator() method in Java, exception import java.util.concurrent.CopyOnWriteArrayList; import java.util.*; public class GFG { public static void main(String[] args) { // create object of CopyOnWriteArrayList CopyOnWriteArrayList<String> ArrLis = new CopyOnWriteArrayList<String>(); // Add elements ArrLis.add( "gopal" ); ArrLis.add( "gfg" ); ArrLis.add( "jgec" ); ArrLis.add( "sudo" ); // print CopyOnWriteArrayList System.out.println( "CopyOnWriteArrayList: " + ArrLis); // Call listIterator() method from 6th index // hence exception is returned Iterator iteratorVals = ArrLis.listIterator( 6 ); // Print elements of iterator // created from CopyOnWriteArrayList System.out.println( "The iterator values" + " of CopyOnWriteArrayList are:" ); // prints the elements using an iterator while (iteratorVals.hasNext()) { System.out.println(iteratorVals.next()); } } } |
Output:
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 6 at java.util.concurrent.CopyOnWriteArrayList.listIterator(CopyOnWriteArrayList.java:1107) at GFG.main(GFG.java:25)
Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#listIterator–