Adobe-Consulting-Services/acs-aem-commons

        folderList.stream().peek(folderList::remove).forEach(folder -> {

Close

According to its JavaDocs, the intermediate Stream operation java.util.Stream.peek() “exists mainly to support debugging” purposes.

A key difference with other intermediate Stream operations is that the Stream implementation is free to skip calls to peek() for optimization purpose. This can lead to peek() being unexpectedly called only for some or none of the elements in the Stream.

As a consequence, relying on peek() without careful consideration can lead to error-prone code.

This rule raises an issue for each use of peek() to be sure that it is challenged and validated by the team to be meant for production debugging/logging purposes.

Noncompliant Code Example

Stream.of("one", "two", "three", "four")
         .filter(e -> e.length() > 3)
         .peek(e -> System.out.println("Filtered value: " + e)); // Noncompliant

Compliant Solution

Stream.of("one", "two", "three", "four")
         .filter(e -> e.length() > 3)
         .foreach(e -> System.out.println("Filtered value: " + e));

See

• Java 8 API Documentation
• 4comprehension: Idiomatic Peeking with Java Stream API
• Data Geekery: 10 Subtle Mistakes When Using the Streams API

        assetList.stream().peek(assetList::remove).forEach(path -> {

Close

According to its JavaDocs, the intermediate Stream operation java.util.Stream.peek() “exists mainly to support debugging” purposes.

A key difference with other intermediate Stream operations is that the Stream implementation is free to skip calls to peek() for optimization purpose. This can lead to peek() being unexpectedly called only for some or none of the elements in the Stream.

As a consequence, relying on peek() without careful consideration can lead to error-prone code.

This rule raises an issue for each use of peek() to be sure that it is challenged and validated by the team to be meant for production debugging/logging purposes.

Noncompliant Code Example

Stream.of("one", "two", "three", "four")
         .filter(e -> e.length() > 3)
         .peek(e -> System.out.println("Filtered value: " + e)); // Noncompliant

Compliant Solution

Stream.of("one", "two", "three", "four")
         .filter(e -> e.length() > 3)
         .foreach(e -> System.out.println("Filtered value: " + e));

See

• Java 8 API Documentation
• 4comprehension: Idiomatic Peeking with Java Stream API
• Data Geekery: 10 Subtle Mistakes When Using the Streams API

        if (!reportData.containsKey(path)) {

Close

It's a common pattern to test the result of a java.util.Map.get() against null or calling java.util.Map.containsKey() before proceeding with adding or changing the value in the map. However the java.util.Map API offers a significantly better alternative in the form of the computeIfPresent() and computeIfAbsent() methods. Using these instead leads to cleaner and more readable code.

Note that this rule is automatically disabled when the project's sonar.java.source is not 8.

Noncompliant Code Example

V value = map.get(key);
if (value == null) {  // Noncompliant
  value = V.createFor(key);
  if (value != null) {
    map.put(key, value);
  }
}
if (!map.containsKey(key)) {  // Noncompliant
  value = V.createFor(key);
  if (value != null) {
    map.put(key, value);
  }
}
return value;

Compliant Solution

return map.computeIfAbsent(key, k -> V.createFor(k));

Exceptions

This rule will not raise an issue when trying to add null to a map, because computeIfAbsent will not add the entry if the value returned by the function is null.

See also

• {rule:java:S6104} - Map "computeIfAbsent()" and "computeIfPresent()" should not be used to add "null" values.

 * ACS AEM Commons

Close

Checks the header of a source file against a header that contains aregular expression for each line of the source header.

Rationale: In some projects checking against afixed header is not sufficient, e.g. the header might require acopyright line where the year information is not static.

For example, consider the following header:

<source><br>line 1: ^/{71}$<br>line 2: ^// checkstyle:$<br>line 3: ^// Checks Java source code for adherence to a set of rules\.$<br>line 4: ^// Copyright \(C\) \d\d\d\d Oliver Burn$<br>line 5: ^// Last modification by \$Author.*\$$<br>line 6: ^/{71}$<br>line 7:<br>line 8: ^package<br>line 9:<br>line 10: ^import<br>line 11:<br>line 12: ^/\*\*<br>line 13: ^ \*([^/]|$)<br>line 14: ^ \*/<br> </source>

Lines 1 and 6 demonstrate a more compact notation for 71 '/'characters. Line 4 enforces that the copyright notice includes afour digit year. Line 5 is an example how to enforce revisioncontrol keywords in a file header. Lines 12-14 is a template forjavadoc (line 13 is so complicated to remove conflict with and ofjavadoc comment). Lines 7, 9 and 11 will be treated as '^$' andwill forcefully expect the line to be empty.

Different programming languages have different comment syntaxrules, but all of them start a comment with a non-wordcharacter. Hence you can often use the non-word characterclass to abstract away the concrete comment syntax and allowchecking the header for different languages with a singleheader definition. For example, consider the following headerspecification (note that this is not the full Apache licenseheader):

<source><br>line 1: ^#!<br>line 2: ^&lt;\?xml.*&gt;$<br>line 3: ^\W*$<br>line 4: ^\W*Copyright 2006 The Apache Software Foundation or its licensors, as applicable\.$<br>line 5: ^\W*Licensed under the Apache License, Version 2\.0 \(the "License"\);$<br>line 6: ^\W*$<br> </source>

Lines 1 and 2 leave room for technical header lines, e.g. the"#!/bin/sh" line in Unix shell scripts, or the XML file headerof XML files. Set the multiline property to "1, 2" so theselines can be ignored for file types where they do no apply.Lines 3 through 6 define the actual header content. Note howlines 2, 4 and 5 use escapes for characters that have specialregexp semantics.

In default configuration, if header is not specified, the default valueof header is set to null and the check does not rise any violations.

This documentation is written and maintained by the Checkstyle community and is covered under the same license as the Checkstyle project.