Item 57 - Use exceptions only for exceptional conditions

From Effective Java 2/e by Joshua Bloch

1. Exceptions are, as their name implies, to be used only for exceptional conditions; they should never be used for ordi- nary control flow
2. A well-designed API must not force its clients to use exceptions for ordinary control flow

Example #1

 // Horrible abuse of exceptions. Don't ever do this!
try {
   int i = 0;
   while(true)
      range[i++].climb();
} catch(ArrayIndexOutOfBoundsException e) {
}

for (Mountain m : range)
   m.climb();

• Because exceptions are designed for exceptional circumstances, there is little incentive for JVM implementors to make them as fast as explicit tests.
• Placingcodeinsideatry-catchblockinhibitscertainoptimizationsthatmod- ern JVM implementations might otherwise perform.
• The standard idiom for looping through an array doesn’t necessarily result in redundant checks. Modern JVM implementations optimize them away.

Example #2

// Do not use this hideous code for iteration over a collection!
try {
   Iterator<Foo> i = collection.iterator();
   while(true) {
      Foo foo = i.next();
      ...
   }
} catch (NoSuchElementException e) {
}

for (Iterator<Foo> i = collection.iterator(); i.hasNext(); ) {
   Foo foo = i.next();
   ...
}

Posted by The Finest Artist