== Why is this an issue?

When directly subclassing ``++java.io.InputStream++`` or ``++java.io.FilterInputStream++``, the only requirement is that you implement the method ``++read()++``. However most uses for such streams don't read a single byte at a time and the default implementation for ``++read(byte[],int,int)++`` will call ``++read(int)++`` for every single byte in the array which can create a lot of overhead and is utterly inefficient. It is therefore strongly recommended that subclasses provide an efficient implementation of ``++read(byte[],int,int)++``.


This rule raises an issue when a direct subclass of ``++java.io.InputStream++`` or ``++java.io.FilterInputStream++`` doesn't provide an override of ``++read(byte[],int,int)++``.


=== Noncompliant code example

[source,java]
----
public class MyInputStream extends java.io.InputStream {
  private FileInputStream fin;

  public MyInputStream(File file) throws IOException {
    fin = new FileInputStream(file);
  }

  @Override
  public int read() throws IOException {
    return fin.read();
  }
}
----


=== Compliant solution

[source,java]
----
public class MyInputStream extends java.io.InputStream {
  private FileInputStream fin;

  public MyInputStream(File file) throws IOException {
    fin = new FileInputStream(file);
  }

  @Override
  public int read() throws IOException {
    return fin.read();
  }

  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    return fin.read(b, off, len);
  }
}
----


=== Exceptions

This rule doesn't raise an issue when the class is declared ``++abstract++``.


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

* Provide an override of "read(byte[],int,int)" for this class.


=== Highlighting

Class name declaration


'''
== Comments And Links
(visible only on this page)

=== relates to: S4349

endif::env-github,rspecator-view[]