Coding Convention

Argument Assumption

• All method arguments are non-null unless explicitely stated otherwise in javadoc.

<syntaxhighlight lang="java">

   /**
     * Read value from a file
     *
     * @param file 
     */
   void read(File file);

   // Non-null assumption applies here too, is is mandatory.
   void read(InputStream is);

   /**
     * Write or remove existing value.
     *
     * @param newValue new value or null</t>> to remove the existing value
     */
   void setValue(Object newValue);

</syntaxhighlight>

Trust your assumptions

Just write the code - you have a code of conduct, the callee can trust the caller.

<syntaxhighlight lang="java">

   void read(InputStream is) {
       int  x = is.read();
   }

</syntaxhighlight>

And caller the callee.

<syntaxhighlight lang="java">

   System.out.println( serialiser.deserialize( is ) );

</syntaxhighlight>

There is no need to do redundant checking, especially at run-time.

<syntaxhighlight lang="java">

   void read(InputStream is) {
       if ( is == null ) throw IllegalArgumentException("Non-null argument");
       int  x = is.read();
   }

</syntaxhighlight>

<syntaxhighlight lang="java">

   Object x = serializer.deserialize( is );
   if ( x != null ) System.out.println( x );

</syntaxhighlight>

Use assertions if you must. Sometimes they improve quality and debuggability.

<syntaxhighlight lang="java" style="background: #dfd;">

   void read(InputStream is) {
       assert( is != null );
       int  x = is.read();
   }

</syntaxhighlight>

Return value assumption

All non-void methods return a non-null value unless expilitely stated otherwise in javadoc.