switch : Java Glossary

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switch

Java’s N-way branch. In the JVM (Java Virtual Machine) there are two different ways of implementing a switch, tableswitch and lookupswitch. The efficient tableswitch is a jump table used when the switch values are reasonably dense e.g. numbered 0..N. The less efficient lookupswitch is a binary search used when the switch values all over the map. It thus pays to keep your switch values dense i.e. sequential.

The most common error with switch is to forget the break. Then one case falls through into the next.

// S W I T C H / C A S E
switch ( n )
   {
   case 1: out.println( "one" );
      break;
   case 2: out.println( "two" );
      break;
   default: out.println( "something else" );
   }// end switch (n)

Case Labels

Case labels must be: Case labels may not be:

Example of Use

Learning More

Oracle’s Technote Guide on String case labels in JDK 1.7+ : available:

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