What is enchanced for loop?

Answer 1

The enhanced for loop, new to Java 6, is a specialized for loop that simplifies looping through an array or a collection. In this chapter we're going to focus on using the enhanced for to loop through arrays. We'll revisit the enhanced for as we discuss collections in the future chapter.

Instead of having three components, the enhanced for has two.

for(declaration : expression)

The two pieces of the for statement are

• declaration The newly declared block variable, of a type compatible with the elements of the array you are accessing. This variable will be available within the for block, and its value will be the same as the current array element.

• expression This must evaluate to the array you want to loop through. This could be an array variable or a method call that returns an array. The array can be any type: primitives, objects, even arrays of arrays.

Using the above definitions, let's look at some legal and illegal enhanced for declarations:

String [] sNums = {"one", "two", "three"};

// legal 'for' declarations

for(String s : sNums) ; // loop thru the array of Strings

The enhanced for loop assumes that, barring an early exit from the loop, you'll always loop through every element of the array. The following discussions of break and continue apply to both the basic and enhanced for loops.