Fail Fast and Fail Safe Iterators in Java.

In this article, I will explain how those collections behave.Java SE specifications don’t use the term fail-safe, so there is no term for it.Concurrent modification in programming means to modify an object concurrently when another task is already running over it.Java can be used to modify a collection when another thread is iterating over it.If this behavior is detected, some Iterator implementations may choose to throw ConcurrentModificationException.If there is structural modification of the collection,Fail-Fast iterators immediately throw ConcurrentModificationException.Structural modification means adding, removing elements from a collection.Fail-fast Iterators don’t throw any exceptions if a collection is modified while iterating over it.They are called fail-safe iterators because they operate on a clone of the original collection.The ConcurrentHashMap classes are examples of fail-safe Iterators.When a collection is modified, fail-fast iterators use an internal flag called modCount which is updated each time.The ConcurrentModificationException can be thrown if it finds that the modCount has been changed after this iterator is created.java code to illustrate Fail Fast Iterator in javaThe java.util.ConcurrentModificationException is in the main thread.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

If there is structural modification of the collection,Fail-Fast iterators immediately throw ConcurrentModificationException.Structural modification means adding, removing elements from a collection.Fail-fast Iterators don’t throw any exceptions if a collection is modified while iterating over it.They are called fail-safe iterators because they operate on a clone of the original collection.The ConcurrentHashMap classes are examples of fail-safe Iterators.When a collection is modified, fail-fast iterators use an internal flag called modCount which is updated each time.The ConcurrentModificationException can be thrown if it finds that the modCount has been changed after this iterator is created.java code to illustrate Fail Fast Iterator in javaThe java.util.ConcurrentModificationException is in the main thread.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

If there is structural modification of the collection,Fail-Fast iterators immediately throw ConcurrentModificationException.Structural modification means adding, removing elements from a collection.Fail-fast Iterators don’t throw any exceptions if a collection is modified while iterating over it.They are called fail-safe iterators because they operate on a clone of the original collection.The ConcurrentHashMap classes are examples of fail-safe Iterators.When a collection is modified, fail-fast iterators use an internal flag called modCount which is updated each time.The ConcurrentModificationException can be thrown if it finds that the modCount has been changed after this iterator is created.java code to illustrate Fail Fast Iterator in javaThe java.util.ConcurrentModificationException is in the main thread.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

When a collection is modified, fail-fast iterators use an internal flag called modCount which is updated each time.The ConcurrentModificationException can be thrown if it finds that the modCount has been changed after this iterator is created.java code to illustrate Fail Fast Iterator in javaThe java.util.ConcurrentModificationException is in the main thread.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

When a collection is modified, fail-fast iterators use an internal flag called modCount which is updated each time.The ConcurrentModificationException can be thrown if it finds that the modCount has been changed after this iterator is created.

The India Exception is in the thread “main”.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

If a collection is modified while iterating over it, fail-fast iterators throw ConcurrentModificationException.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

The fail-fast behavior of an iterator cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification.ConcurrentModificationException is thrown on a best-effort basis.The fail-fast behavior of iterators should only be used to detect bugs.ConcurrentModificationException will be thrown in case of removing via a particular method.java code to demonstrate remove case in Fail-fast iteratorsI am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

The java.util.ConcurrentModificationException is in the main thread.I am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

Java SE specifications don’t use the term fail-safe, so there is no term for it.I am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

Java SE specifications don’t use the term fail-safe, so there is no term for it.I am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

Java SE specifications don’t use the term fail-safe, so there is no term for it.I am demonstrating the difference between Fail Fast and Non-Fail Fast Iterator.The iterators make a copy of the internal collection and then duplicate it.The copied collection is not affected by structural modification to the iterator.The original collection remains the same.If a collection is modified while iterating over it, fail-safe iterators don’t throw anException.The example of Fail Safe Iterator in Java is ConcurrentHashMap.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

The collections which don’t use fail-fast concept may not create clone/snapshot of it in memory to avoid ConcurrentModificationException.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

Collections that don’t use fail-fast concept may not create clone/snapshot of it in memory to avoid ConcurrentModificationException.Although it is not fail-fast, ConcurrentHashMap does not operate on a separate copy.The official specification describes the memory consistency properties in Java as weakly consistent.There is a example of Fail-Safe Iterator which does not create separate copy Java and Java program to illustrate.It has not created a separate copy map.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.

The iterators returned by ConcurrentHashMap are weakly consistent.The iterator can tolerate concurrent modification, traverses elements as they existed when it was constructed and may reflect modifications to the collection after the construction.Fail safe iterator is called fail safe because they work on a clone of collection instead of the original collection.Readers, attention reader!Don’t stop learning.The Fundamentals of Java and Java Collections course is student-friendly and will help you become industry ready.To complete your preparation from learning a language to interviewing, please refer the Complete Interview preparation course.