Azure Spring Apps is a fully managed service from Microsoft
(built in collaboration with VMware), focused on building and
deploying Spring Boot applications on Azure Cloud without
worrying about Kubernetes.
The Enterprise plan comes with some interesting features, such
as commercial Spring runtime support, a 99.95% SLA and some deep
discounts (up to 47%) when you are ready for production.
And, you can participate in a very quick (1 minute) paid user
research from the Java on Azure product team.
Partner – Aegik AB – NPI EA (cat=JPA)
Slow MySQL query performance is all too common. Of course
it is. A good way to go is, naturally, a dedicated profiler that
actually understands the ins and outs of MySQL.
The Jet Profiler was built for MySQL only, so it can do
things like real-time query performance, focus on most used tables
or most frequent queries, quickly identify performance issues and
basically help you optimize your queries.
Critically, it has very minimal impact on your server's
performance, with most of the profiling work done separately - so
it needs no server changes, agents or separate services.
Basically, you install the desktop application, connect to your MySQL
server, hit the record button, and you'll have results
within minutes:
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With best-in-class guides and documentation, Payara
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optimize Jakarta EE applications.
The goal is to apply an opinionated approach to get to
what's essential for mission-critical applications - really solid
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Looking for the ideal Linux distro for running modern Spring
apps in the cloud?
Meet Alpaquita Linux: lightweight, secure, and powerful
enough to handle heavy workloads.
This distro is specifically designed for running Java
apps. It builds upon Alpine and features significant
enhancements to excel in high-density container environments while
meeting enterprise-grade security standards.
Specifically, the container image size is ~30% smaller than
standard options, and it consumes up to 30% less RAM:
Yes, Spring Security can be complex, from the more advanced
functionality within the Core to the deep OAuth support in the
framework.
I built the security material as two full courses - Core and
OAuth, to get practical with these more complex scenarios. We
explore when and how to use each feature and code through it on
the backing project.
DbSchema is a super-flexible database designer, which can
take you from designing the DB with your team all the way to
safely deploying the schema.
The way it does all of that is by using a design model, a
database-independent image of the schema, which can be shared in a
team using GIT and compared or deployed on to any database.
And, of course, it can be heavily visual, allowing you to
interact with the database using diagrams, visually compose
queries, explore the data, generate random data, import data or
build HTML5 database reports.
Slow MySQL query performance is all too common. Of course
it is. A good way to go is, naturally, a dedicated profiler that
actually understands the ins and outs of MySQL.
The Jet Profiler was built for MySQL only, so it can do
things like real-time query performance, focus on most used tables
or most frequent queries, quickly identify performance issues and
basically help you optimize your queries.
Critically, it has very minimal impact on your server's
performance, with most of the profiling work done separately - so
it needs no server changes, agents or separate services.
Basically, you install the desktop application, connect to your MySQL
server, hit the record button, and you'll have results
within minutes:
Creating PDFs is actually surprisingly hard. When we
first tried, none of the existing PDF libraries met our needs. So
we made DocRaptor for ourselves and later launched it as one
of the first HTML-to-PDF APIs.
We think DocRaptor is the fastest and most scalable way to
make PDFs, especially high-quality or complex PDFs. And as
developers ourselves, we love good documentation, no-account trial
keys, and an easy setup process.
for loops and Iterators, both provide mechanisms to traverse through collections of elements. While both serve the purpose of iterating over collections, they differ in their syntax, functionality, and applicability.
In this tutorial, we’ll explore a detailed comparison between for loops and iterators, highlighting their key distinctions in several aspects.
We’ll use the following list of strings to demonstrate:
In this section, we’ll explore the forward traversal methods for both for loops and iterators.
2.1. With for Loops
Traditional for loops in Java are designed for forward iteration. They start from an initial index and move toward the end of the collection, processing each element in sequential order.
Let’s iterate forward using a for loop:
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < names.size(); i++) {
stringBuilder.append(names.get(i));
}
assertEquals("AliceBobCharlie", stringBuilder.toString());
2.2. With Iterators
Iterators, by default, offer forward-only traversal. The hasNext() method checks for the existence of the next element, and the next() method moves the iterator to the next position in the collection:
StringBuilder stringBuilder = new StringBuilder();
Iterator<String> iterator = names.iterator();
while (iterator.hasNext()) {
stringBuilder.append(iterator.next());
}
assertEquals("AliceBobCharlie", stringBuilder.toString());
3. Backward Traversal
In this section, we’ll explore the backward traversal methods for both for loops and iterators.
3.1. With for Loops
While it’s possible to simulate backward traversal by manipulating the for loop variable, it isn’t as straightforward as forward iteration. Let’s iterate backward using a for loop:
StringBuilder stringBuilder = new StringBuilder();
for (int i = names.size() - 1; i >= 0; i--) {
stringBuilder.append(names.get(i));
}
assertEquals("CharlieBobAlice", stringBuilder.toString());
3.2. With Iterators
However, if a collection implements the List interface and provides a ListIterator, we can achieve backward iteration using the hasPrevious() and previous() methods:
StringBuilder stringBuilder = new StringBuilder();
ListIterator<String> listIterator = names.listIterator(names.size());
while (listIterator.hasPrevious()) {
stringBuilder.append(listIterator.previous());
}
assertEquals("CharlieBobAlice", stringBuilder.toString());
4. Removal of Elements
In this section, we’ll explore the remove methods in both for loops and iterators.
4.1. With for Loops
for loops aren’t directly compatible with removing elements from the collection being traversed. Modifying the collection during a for loop iteration can lead to unpredictable behavior as the size of the collection is modified. This often results in ConcurrentModificationException or incorrect indices.
Let’s test out the remove() method during looping:
assertThrows(ConcurrentModificationException.class, () -> {
for (String name : names) {
names.remove("Bob");
}
});
4.2. With Iterators
Iterators, on the other hand, provide a safe and reliable way to remove elements during iteration using the remove() method.Iterator internally maintains a cursor or a position within the collection. When we call remove(), it knows exactly which element to remove based on its internal state. This prevents concurrent modification issues and ensures the integrity of the iteration process.
Let’s test out the remove() method with Iterator:
Iterator<String> iterator = names.iterator();
while (iterator.hasNext()) {
String name = iterator.next();
if (name.equals("Bob")) {
iterator.remove();
}
}
List<String> expected = Arrays.asList("Alice", "Charlie");
assertIterableEquals(expected, names);
5. Flexibility
In this section, we’ll explore the flexibility to alter elements during iteration in both for loops and iterators.
5.1. With for Loops
for loops provide direct access to the elements of a collection based on their indices. This offers flexibility in terms of modification and access, as we have explicit control over the index and can easily perform insertions and modification operations:
for (int i = 0; i < names.size(); i++) {
names.set(i, names.get(i).toLowerCase());
}
List<String> expected = Arrays.asList("alice","bob", "charlie");
assertIterableEquals(expected, names);
5.2. With Iterators
Iterators, while excellent for traversal and removal, don’t provide direct access to index-based operations. The Iterator interface focuses on forward-only traversal and removal, limiting the ability to directly insert or modify elements. If we need to add or modify elements using Iterator, we may want to consider ListIterator.
6. Error-proneness
for loops are more prone to errors due to their reliance on index-based access. Incorrect index values or modifications to the collection during iteration can lead to various exceptions and unexpected behavior. For example, for loop can lead to IndexOutOfBoundException if the index value is outside the bounds of the collection. This can happen if the index variable isn’t properly initialized or if the collection size is modified during iteration.
On the other hand, Iterator enforces hasNext() checks before accessing elements, preventing null pointer exceptions. This ensures that the Iterator points to a valid element before attempting to access it.
7. Code Readability
for loops are generally considered more readable and concise for simple iterations over collections due to their straightforward syntax. The loop structure clearly conveys the iteration logic, with the index variable explicitly indicating the current position in the collection. This makes it easy to understand the code and follow the flow of the iteration.
While Iterator offers benefits for complex scenarios, it can introduce some readability challenges for simple iterations. Iterators require method calls like hasNext() or next() to iterate through the collection. These method calls can introduce additional complexity and make the iteration logic less clear compared to the concise syntax of a for loop.
8. Choosing Between Iterators and for Loops
In summary, for loops are suitable for simple iteration, especially when direct access to indices is beneficial.
Iterators, on the other hand, are powerful when dealing with safe removal, forward-only traversal, and when working with various collection types.
The following table shows the main differences between the for loop and Iterator:
Feature
for Loop
Iterator
Traversal Direction
Forward and backward using indexing
Forward (default), bidirectional with ListIterator
Element Removal
Not directly compatible, can lead to errors
Safe and reliable using remove() method
Flexibility – Insert, Access, Modify
Direct index-based access
Limited to forward-only traversal and removal; ListIterator for modification while iterating
Error-proneness
More prone to errors due to index-based access and potential modifications
In this article, we discussed the difference between for loops and an Iterators.
for loops provides a straightforward approach for simple forward traversal, while Iterators are powerful when dealing with safe removal and forward-only traversal.
As always, the source code for the examples is available over on GitHub.
Partner – Bellsoft – NPI EA (cat = Spring)
Looking for the ideal Linux distro for running modern Spring
apps in the cloud?
Meet Alpaquita Linux: lightweight, secure, and powerful
enough to handle heavy workloads.
This distro is specifically designed for running Java
apps. It builds upon Alpine and features significant
enhancements to excel in high-density container environments while
meeting enterprise-grade security standards.
Specifically, the container image size is ~30% smaller than
standard options, and it consumes up to 30% less RAM:
Creating PDFs is actually surprisingly hard. When we
first tried, none of the existing PDF libraries met our needs. So
we made DocRaptor for ourselves and later launched it as one
of the first HTML-to-PDF APIs.
We think DocRaptor is the fastest and most scalable way to
make PDFs, especially high-quality or complex PDFs. And as
developers ourselves, we love good documentation, no-account trial
keys, and an easy setup process.
Slow MySQL query performance is all too common. Of course
it is.
The Jet Profiler was built entirely for MySQL, so it's
fine-tuned for it and does advanced everything with relaly minimal
impact and no server changes.
Basically, write code that works the way you meant it to.
Partner – Machinet – NPI EA (cat = Testing)
AI is all the rage these days, but for very good reason. The
highly practical coding companion, you'll get the power of
AI-assisted coding and automated unit test generation.
Machinet's Unit Test AI Agent utilizes your own project
context to create meaningful unit tests that intelligently aligns
with the behavior of the code.