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++``.


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