`Arrays` should not be copied using loops.`RSPEC-3012`

Using a loop to copy an array or a subset of an array is simply wasted code when there are built-in functions to do it for you. Instead, use Arrays.copyOf to copy an entire array into another array, use System.arraycopy to copy only a subset of an array into another array, and use Arrays.asList to feed the constructor of a new list with an array.

Note that Arrays.asList simply puts a Collections wrapper around the original array, so further steps are required if a non-fixed-size List is desired.

Noncompliant Code Example

public void makeCopies(String[] source) {

  this.array = new String[source.length];
  this.list = new ArrayList(source.length);

  for (int i = 0; i < source.length; i++) {
    this.array[i] = source[i]; // Noncompliant
  }

  for (String s : source) {
    this.list.add(s); // Noncompliant
  }
}

Compliant Solution

public void makeCopies(String[] source) {
  this.array = Arrays.copyOf(source, source.length);
  Collections.addAll(this.list, source);
}

Exceptions

Rule detects only the most idiomatic patterns, it will not consider loops with non-trivial control flow. For example, array elements that are copied conditionally are ignored.

public int[] getCopy(int[] source) {
  int[] dest = new int[source.length];
  for (int i = 0; i < source.length; i++) {
    if (source[i] > 10) {
      dest[i] = source[i];  // Compliant
    }
  }
  return dest;
}

https://rules.sonarsource.com/java/RSPEC-3012

Start by reviewing the repository's existing Java static-analysis recipes and tests, then compare their structure with the RSPEC-3012 examples in this issue. Done means the recipe identifies straightforward loops that copy arrays or populate lists while ignoring loops with non-trivial control flow, with tests covering the compliant and noncompliant examples.