New patterns

[brunoborges]

Some missing bits:

• markdown comments
  /// This is a javadoc comment

• static method in interface (Java 8)

• static member in inner classes (Java 16)

  class Main {
  class Book {
  static int globalBookCount;

   Book() {
    globalBookCount++;
   }
  

  }
  }

• compact canonical constructor (for preconditions) (Java 15 ?)

  public record Person(String name, List pets) {
  public {
  Objects.requireNonNull(name);
  pets = List.copyOf(pets);
  }
  }

• loop over a List in reverse order

  for(Iterator iterator = list.listIerator(list.isze()); iterator.hasPrevious();) {
  String element = iterator.previous();
  ...
  }

vs

for(String element : list.reversed()) {
...
}

• File mapping in memory

  FileChannel channel = ...
  MappedByteBuffer buffer = channel.map( FileChannel.MapMode.READ_WRITE, 0, (int) channel.size());
  // file size limited to 2G
  // freed by the GC, no control

vs

FileChannel channel = ...
try (Arena arena = Arena.ofShared()) {
MemorySegment segment = channel.map( FileChannel.MapMode.READ_WRITE, 0, channel.size(), arena);
// no file size limit
...
} // call close() => freed

• The example of "writing files" old style is wrong
  try(BufferedWriter writer = new BufferedWriter(new FileReader(path))) {
  ...
  }

  here if the new BufferedWriterfails to allocate the buffer, close() is not called on the FileReader,
  it should be (using two lines)

  try(FileWriter fileWriter = new FileReader(path);
  BufferedWriter writer = new BufferedWriter(fileWriter)) {
  ...
  }