Add elements to a List while iterating over it. (Java) [duplicate]

by

You can’t modify a Collection while iterating over it using an Iterator, except for Iterator.remove().

However, if you use the listIterator() method, which returns a ListIterator, and iterate over that you have more options to modify. From the javadoc for add():

The new element is inserted before the implicit cursor: … a subsequent call to previous() would return the new element

Given that, this code should work to set the new element as the next in the iteration:

ListIterator<T> i;
i.add(e);
i.previous(); // returns e
i.previous(); // returns element before e, and e will be next

This will work except when the list starts iteration empty, in which case there will be no previous element. If that’s a problem, you’ll have to maintain a flag of some sort to indicate this edge case.

More Related Contents:

  1. ListIterator Strange Adding to ArrayList
  2. Difference between Iterator and Listiterator?
  3. Using bitwise operator to divide by 0 (Simulation of division by 0) [closed]
  4. What’s wrong with this input? [closed]
  5. How can I convert a .jar to an .exe?
  6. RESTful call in Java
  7. Invoking a static method using reflection
  8. What is resource-ref in web.xml used for?
  9. How do I round a double to two decimal places in Java? [duplicate]
  10. Setter methods or constructors
  11. Create XML file using java
  12. What is the difference between Optional.flatMap and Optional.map?
  13. Ambari 2.7.5 installation failure on CentOS 7
  14. Java applet manifest – Allow all Caller-Allowable-Codebase
  15. How can I use hibernate with MS Access?
  16. Hot swapping in Spring Boot
  17. repository element was not specified in the POM inside distributionManagement element or in -DaltDep loymentRepository=id::layout::url parameter
  18. Why doesn’t changing the pre to the post increment at the iteration part of a for loop make a difference?
  19. Change position of Google Maps API’s “My location” button
  20. What is a good 64bit hash function in Java for textual strings?
  21. How does long to int cast work in Java?
  22. Trying to call a JavaFX application from Java… NoSuchMethodException
  23. Format a message using MessageFormat.format() in Java
  24. (no) Properties in Java?
  25. How to make Eclipse see the changes in Play! compiled templates?
  26. Measuring time spent on GC
  27. How to remove element from an array
  28. Why is subtracting these two epoch-milli Times (in year 1927) giving a strange result?
  29. How to get jdbc connection from hibernate session? [duplicate]
  30. How to transmit live video from within a Java application?

Leave a Comment