Equivalent Statements

Here is the original fragment, which uses AND:

if (  !(speed > 2000 && memory > 512)  )
  System.out.println("Reject this computer");
else
  System.out.println("Acceptable computer");

Here is an equivalent fragement that uses OR:

if (  speed <= 2000  ||  memory <= 512 )
  System.out.println("Reject this computer");
else
  System.out.println("Acceptable computer");

Yet another equivalent fragment reverses the order of the true and false branches of the statement:

if (  speed > 2000  &&  memory > 512 )
  System.out.println("Acceptable computer");
else
  System.out.println("Reject this computer");

The last fragment is probably the best choice because it is the easiest to read. It follows the form:

if ( expression that returns "true" for the desired condition )
  perform the desired action
else
  perform some other action

Generally, people find statements that involve NOT to be confusing. Avoid using using NOT, if you can. If NOTs are needed, try to apply them to small subexpressions, only.