Three ways to iterate through a collection in Java _java

For iterating through the collection to get its object , here's a summary of the three simple ways

Mode one: Make the collection into an array and iterate through the array

object[] obj = List.toarray ();
for (Object s:obj) {
System.out.println ((String) s);
}

Way two: Get () method gets. But only used in the list collection, only the list collection has index values.

for (int i = 0;i<list.size (); i++) {
System.out.println (List.get (i));
}

Mode three: through the iterator

Listiterator it = List.listiterator ();
while (It.hasnext ()) {
   System.out.println (It.next ());
}

There are two cases to compare

Collection Case:

Import java.util.ArrayList;
Import java.util.Collection;
Import Java.util.Iterator;
Import java.util.List;
  public class Pasework {public static void main (string[] args) {collectiontest ();
    public static void Collectiontest () {Collection <string>collection = new arraylist<string> ();
    Collection.add ("the Junior");
    Collection.add ("small Two");
    Collection.add ("John");
    Collection.add ("Dick");
    Collection.add ("Harry");
    1. Set to array object[] object[] OBJECTSARRC = Collection.toarray (); For (object OBJECT:OBJECTSARRC) {string string = (String) object;//cast object to string output System.out.println (Strin
    g); The//2.get () method gets the element for (int i = 0;i < Collection.size (); i++) {//get () can only be used in the list collection, so you need to convert the form here Syst
    Em.out.println (((arraylist<string>) collection). Get (i));
    //3. iterator iterator<string> it = Collection.iterator ();
    while (It.hasnext ()) {System.out.println (It.next ()); }
  }  
}

List Case:

Import java.util.ArrayList;
Import java.util.Collection;
Import java.util.List;
Import Java.util.ListIterator;
public class Pasework {public
  static void Main (string[] args) {
    listtest ();
  }
  public static void Listtest () {
    list<string> List = new arraylist<string> ();
    List.add ("the Junior");
    List.add ("small Two");
    List.add ("John");
    List.add ("Dick");
    List.add ("Harry");
    1. Set to array object[]
    object[] objectsarrl = List.toarray ();
    For (object object:objectsarrl) {
      string = (String) object;//cast object to string output
      System.out.println (string );
    }
    2. Through get () method for
    (int i = 0; i < list.size (); i++) {
      System.out.println (List.get (i));
    }  
    3. Iterator
    listiterator<string> iterator = List.listiterator ();
    while (Iterator.hasnext ()) {
      System.out.println (Iterator.next ());
    }
}}

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