Difference Between Collection.stream().forEach() and Collection.forEach() in Java

Collection.forEach() and Collection.stream().forEach() are both used for iterating across the collections and are not significantly different from one another. There is no major difference between the two, as both of them provide the same result. However, there are some.

Collection.stream().forEach() Method

Iteration in a group of objects is essentially accomplished by transforming a collection into a stream and then iterating over the stream of collections using Collection.stream().forEach(). The concurrent modification exception will be raised if any structural changes are made to the collection while iterating over it.

Iterating over members of a collection using streams in Java is made possible via the Collection.stream().forEach() method, which allows for functional-style operations. When combined with a parallel stream, it processes components in parallel, which makes it appropriate for huge datasets where speed optimization is required, in contrast to Collection.forEach(), which performs operations on the collection directly, stream().forEach() first transforms the collection into a stream before executing the operation.

This method is frequently applied in Java's Stream API for data conversions, filtering, and parallel processing.

Output:

 20406080 

Collection.forEach() Method

Collection.forEach() makes use of the iterator of the collection (whatever is given). When iterating over a collection, most of them do not permit structural changes. They will raise the concurrent modification error if there are any modifications made to that collection, such as the addition or deletion of an entry. When iterating over a synchronized collection, collection.forEach() will lock the collection segment and hold it over all possible calls to that collection.

Iterating over the components of a collection in a clear and useful manner is made possible by the Collection.forEach() method, which was introduced in Java 8. It can be used with lambda expressions or method references because it is a component of the Iterable interface and takes a Consumer functional interface as a parameter. It works directly with the collection without turning it into a stream, in contrast to stream().forEach().

This technique offers a clear and understandable means of processing and navigating among elements in lists, sets, and other kinds of collections.

Output:

 20406080 

Comparison Between Collection.stream().forEach() and Collection.forEach()

Collection.stream().forEach() and Collection.forEach() MCQs

1. ______________________ used for iterating the collection, but it first changes the collection to the stream and then iterates over the stream of the collection.

1. Collection.stream().forEach()
2. Collection.forEach()
3. Both Collection.stream().forEach() and Collection.forEach()
4. None of these

2. During modification of structure in the collection, the exception will be thrown later in _________________.

1. Collection.stream().forEach()
2. Collection.forEach()
3. Both Collection.stream().forEach() and Collection.forEach()
4. None of these

3. The specific order of execution is not defined in ____________.

1. Collection.forEach()
2. Collection.stream().forEach()
3. do-while loop
4. All of these

4. The collections iterator is used by _______________.

1. Collection.stream().forEach()
2. Collection.forEach()
3. do-while loop
4. None of these

5. Pick the incorrect statement.

1. During modification structure modification in the collection, the exception will be thrown later in Collection.stream().forEach().
2. During modification structure modification in the collection, the exception will be thrown later in Collection.forEach().
3. If iteration is taking place over the synchronized collection, then Collection.stream().forEach() does not do the locking of the collection.
4. If iteration is running across the synchronized collection, then Collection.forEach() locks the collection and holds it throughout all the calls.