A brief talk on Java enhanced for-loop for Each_java

For-each Cycle

The For-each loop is also called an enhanced for loop, or a foreach loop.

The For-each loop is a new feature of the JDK5.0 (other new features such as generics, automatic boxing, etc.).

The addition of the For-each loop simplifies the traversal of the set.

The syntax is as follows:

for (type Element:array)

{

   System.out.println (element);

}

Example

Its basic use can look directly at the code:

Two for loops are first compared in the code, then the two-dimensional array is traversed with an enhanced for loop, and a list collection is traversed in three different ways.

Import java.util.ArrayList;
Import Java.util.Iterator;

Import java.util.List;
    
    public class Foreachtest {public static void main (string[] args) {int[] arr = {1, 2, 3, 4, 5};
    System.out.println ("----------old way to traverse------------");
    Legacy mode for (int i=0; i<arr.length; i++) {System.out.println (arr[i]);
    
    } System.out.println ("---------New way to traverse-------------");
    New notation, enhanced for loop for (int element:arr) {System.out.println (element);
    
    } System.out.println ("---------traversing two-dimensional array-------------");
    
    Traversal two-dimensional array int[][] arr2 = {1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
      For (int[] row:arr2) {for (int element:row) {System.out.println (element);
    
    Three ways to traverse the collection list list<string> list = new arraylist<string> ();
    List.add ("a");
    List.add ("B");
    
    List.add ("C");
    System.out.println ("----------Way 1-----------");
    The first way, the general for loopfor (int i = 0; i < list.size (); i++) {System.out.println (List.get (i));
    } System.out.println ("----------mode 2-----------");
    The second way is to use an iterator for (iterator<string> iter = List.iterator (); Iter.hasnext ();)
    {System.out.println (Iter.next ());
    } System.out.println ("----------mode 3-----------");
      
    The third way is to use the enhanced for loop for (String str:list) {System.out.println (str); }
  }

}

Disadvantages of For-each Loops: Lost index information.

When traversing a collection or array, if you need to access the index of the collection or array, it is best to use the old-fashioned way to implement loops or traversal rather than using an enhanced for loop because it loses subscript information.

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