Improving for loops

[LuisOsv]

User description

🔗 Related Issues

N/A — performance and readability enhancement

💥 What does this PR do?

This PR improves performance and readability by caching the size or length of collections and arrays before entering loops.
Instead of repeatedly calling .size() or .length in the loop condition, the value is stored in a local variable and reused.

🔧 Implementation Notes

This change is based on a common Java performance recommendation highlighted in High Performance with Java by Javier Fernandez Gonzalez (O’Reilly, 2024).
The book explains that repeatedly calling methods like .size() inside loop conditions is less efficient than caching their values in local variables. This approach improves both runtime performance and code readability.
Example refactor:

int size = list.size();
for (int i = 0; i < size; i++) {
    // logic
}

Instead of:

for (int i = 0; i < list.size(); i++) {
    // logic
}

💡 Additional Considerations

• 🔒 No behavioral or logic changes were made.
• ✅ 100% backwards compatible
• 🔍 The refactor strictly targets loop conditions for micro-optimization and readability.
• 🧼 Improves code maintainability by reducing repetition.

🔄 Types of changes

• ✅ Cleanup (formatting, renaming)
• ✅ Performance improvement (non-breaking change)

🧪 Tests Executed
To ensure nothing was broken by this cleanup, the following affected test targets were executed:

bazel test //java/test/org/openqa/selenium/support:SmallTests
bazel test //java/test/org/openqa/selenium/support/pagefactory:SmallTests
bazel test //java/test/org/openqa/selenium/remote:small-tests
bazel test //java/test/org/openqa/selenium/remote/http:small-tests
bazel test //java/test/org/openqa/selenium/support/ui:SmallTests
bazel test //java/test/org/openqa/selenium/grid/node/docker:small-tests
bazel test //java/test/org/openqa/selenium/grid/node/relay:medium-tests
bazel test //java/test/org/openqa/selenium/json:SmallTests

✅ All tests passed successfully.

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PR Type

Enhancement

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Description

• Cache collection/array size in loops for performance

• Refactor for improved code readability and maintainability

• No behavioral or logic changes introduced

• Applied changes across grid, remote, tools, json, and support packages

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Changes walkthrough 📝

Relevant files

Enhancement

14 files JavadocJarMaker.java Cache argument array length before loop for efficiency      +2/-1      ModuleGenerator.java Store argument array length before loop iteration                +2/-1      DockerOptions.java Cache config list size before loop for performance              +3/-2      RelayOptions.java Store config list size before loop for clarity                      +3/-2      JsonInput.java Cache string length before loop for efficiency                      +2/-1      WebElementToJsonConverter.java Cache array length before loop and pre-size list                  +3/-2      AbstractHttpCommandCodec.java Cache list size before loop for efficiency                              +5/-3      Route.java Cache prefix path array length before loop                              +3/-2      UrlTemplate.java Cache group list size before switch and loop                          +3/-2      FindAll.java Cache annotation array length before loop                                +3/-2      FindBys.java Cache annotation array length before loop                                +3/-2      EventFiringDecorator.java Cache parameter array length before loop and comparison    +3/-2      ByChained.java Cache locator array length before loop and checks                +3/-2      Quotes.java Cache substring array length before loop for efficiency    +3/-2

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[CLAassistant]

All committers have signed the CLA.

[selenium-ci]

Thank you, @LuisOsv for this code suggestion.

The support packages contain example code that many users find helpful, but they do not necessarily represent
the best practices for using Selenium, and the Selenium team is not currently merging changes to them.

We actively encourage people to add the wrapper and helper code that makes sense for them to their own frameworks.
If you have any questions, please contact us

[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

🎫 Ticket compliance analysis ❌ 5678 - Not compliant Non-compliant requirements: • Fix ConnectFailure error when instantiating ChromeDriver multiple times Requires further human verification: • The PR doesn't address the ChromeDriver connection issue at all, as it's focused on loop optimization rather than connection handling 1234 - Not compliant Non-compliant requirements: • Fix issue where JavaScript in link's href is not triggered on click() in Firefox Requires further human verification: • The PR doesn't address the Firefox JavaScript click issue at all, as it's focused on loop optimization rather than Firefox-specific behavior

⏱️ Estimated effort to review: 2 🔵🔵⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Potential Bug The variable i is incremented twice in the loop - once in the for loop increment and once manually inside the loop body. This could lead to skipping elements or incorrect indexing. for (int i = 0; i < configsCount; i++) { String imageName = allConfigs.get(i); i++; if (i == configsCount) { Potential Bug The variable i is incremented twice in the loop - once in the for loop increment and once manually inside the loop body. This could lead to skipping elements or incorrect indexing. for (int i = 0; i < configsCount; i++) { int maxSessions; try { maxSessions = Integer.parseInt(extractConfiguredValue(allConfigs.get(i))); } catch (NumberFormatException e) { throw new ConfigException("Unable parse value as number. " + allConfigs.get(i)); } i++;

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Prevent array index bounds exception The pre-increment of i before accessing args[i] can lead to an ArrayIndexOutOfBoundsException if the last argument is a flag without a corresponding value. Use a bounds check before accessing the next argument. java/src/dev/selenium/tools/javadoc/JavadocJarMaker.java [61] -String next = args[++i]; +if (i + 1 < argCount) { + String next = args[++i]; +} else { + throw new IllegalArgumentException("Missing value for flag: " + flag); +} Apply / Chat Suggestion importance[1-10]: 8 __ Why: Valid concern about potential ArrayIndexOutOfBoundsException when args[++i] is called if the last argument is a flag without a corresponding value. This addresses a real runtime error risk.	Medium
	Fix loop iteration pattern The loop manually increments i inside the loop body, which can lead to skipping elements or going out of bounds. Consider using a step of 2 in the loop condition to process pairs of elements safely. java/src/org/openqa/selenium/grid/node/docker/DockerOptions.java [143-149] int configsCount = allConfigs.size(); -for (int i = 0; i < configsCount; i++) { +for (int i = 0; i < configsCount - 1; i += 2) { String imageName = allConfigs.get(i); - i++; - if (i == configsCount) { - throw new DockerException("Unable to find JSON config"); - } + Capabilities stereotype = + options.enhanceStereotype(JSON.toType(allConfigs.get(i + 1), Capabilities.class)); Apply / Chat Suggestion importance[1-10]: 5 __ Why: Identifies a valid issue with the manual increment pattern in the loop, but the improved_code doesn't preserve the original error handling logic and significantly restructures the code without maintaining equivalent functionality.	Low
General	Handle null array elements Initializing the ArrayList with a capacity is good, but if the array contains null elements, they will be added to the list. Consider adding a null check in the loop to handle potential null elements properly. java/src/org/openqa/selenium/remote/WebElementToJsonConverter.java [87-88] int arrayLength = Array.getLength(array); List<Object> list = new ArrayList<>(arrayLength); +for (int i = 0; i < arrayLength; i++) { + Object item = Array.get(array, i); + if (item != null) { + list.add(item); + } +} +return list; Apply / Chat Suggestion importance[1-10]: 3 __ Why: The suggestion changes behavior by filtering out null elements, which may not be intended. The original code was designed to include null values from arrays, and this behavioral change isn't necessarily an improvement.	Low
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