for loop and the list iterator

[vuthlarhi donald]

how can I use the for loop with the list iterator to be able to use the trim method, illustrate by example on this program

  
 
import java.util.*;
/**
 *
 * @author Administrator
 */
public class Coll {
     public static void main(String[] args) {
List <String> list = new ArrayList<String>();
list.add("Donald");
list.add("funny");
list.add("hi");
list.add("heita");
for(String a : list){
    System.out.println(a);
      } }}
 
      

[Raghavan Muthu]

I don't get your doubt. Have you tried running the program? It has the for loop to use the list.

[Raghavan Muthu]

The program seems to use the list object and use strings inside it.

You can directly use the trim() method on 'a' right?

[Bill Shirley]

You may be confusing String.trim() and Iterator.remove().

You would want access to the iterator to remove items from the list. Invoking trim on a string will return a new string instance that has been trimmed (white space removed from the front and back).

To get access to the iterator, you use the old form (pre Java 5) of the for loop.

import java.util.*;
 
public class Coll {
public static void main(String[] args) {
List<String> list = new ArrayList<String>();
list.add("Donald");
list.add("funny");
list.add("hi");
list.add("heita");
 
[B]for (Iterator<String> i = list.iterator(); i.hasNext(); /*blank*/) {
String a = i.next();
if (a.equals("hi"))
i.remove();
}[/B]
 
for (String a : list) {
System.out.println(a);
}
}
}

[Rob Spoor]

Whenever you use the new for loop, you lose the iterator or array indexes. It's a price you pay for the shorter code.

So if you need the iterator to remove items, the array index (e.g. to copy array items) or a list iterator (because of the add and set methods), there is no other option but to use the old for loop.