Java 中的 Iterator 和 Iterable 接口

public class IteratorAndIterable<T> implements Iterable<T>{
	}

//Custom Iterator
public class myCustomiterator < T > implements Iterator < T >
{
//hasNext()
  public boolean hasNext ()
  {
//your code goes here
      return false;
}
//next()
    public E next ()
  {
//your code goes here
      return false;
}
}

import java.util.*;
//Main class
public class ExplainIterator {
	public static void main (String [] args) {
		ArrayList<String> demolist = new ArrayList<String>();
		demolist.add("Here");
		demolist.add("Is");
		demolist.add("Iterator");
		demolist.add("Demo");
		/*
		 * Now, we are going to dynamically generate Iterator from the Arrays List for
		 * traversing each element
		 */
		/*
		 * Iterator method has two parameters: hasNext() and next(). The hasNext()
		 * returns boolean (true or false). While the next() method returns next
		 * complete token (it hasNext() gave it one).
		 */
		Iterator<String> demo = demolist.iterator();
		while (demo.hasNext()) {
			System.out.println(demo.next());
		}
		//Iterator method
}
	//main function
}
//main class

Here
Is
Iterator
Demo

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

//You will inherit it
//Define Custom Iterable
public class IteratorAndIterable<T> implements Iterable<T>{
	//An array list (setL: setlist)
	private List<T> setL = new ArrayList<>();
	//Get value from the List
	public void add(T getback) {
		setL.add(getback);
	}
	//Define Iterator to get your iterable objects
	public Iterator<T> iterator() {
		return new myCi<T>(setL);
	}
	// Your custom iterator overrides Iterator
	public class myCi<E> implements Iterator<E> {
		//For a condition to avoid exception later
		int SP = 0;
		//Custom Array List
		List<E> CAL;
		public myCi(List<E> CAL) {
			this.CAL = CAL;
		}
		//Check the iterator values
		public boolean hasNext() {
			if(CAL.size() >= SP +1) {
				// Remember SP = 0? To avoid exception
				//If hasNext() has value, it returns true
				return true;
			}
			return false;
		}
		//Use next() to get the token that hasNext() just passed
		//No need to use default values, make use of the your custom <E>
		public E next() {
			//Get token and store it into getback
			E getback = CAL.get(SP);
			//You can do anything with this loop now
			SP ++;
			// return getback instead of deafault value (Now check line number 122) It will be clear
			return getback;
		}
		public void remove() {

		}
	}
}

//Get object from the iterable
public abstract class ExecuteIterable {
public static void main(String[] args) {
//Your former class of custom Iterable and Iterator
	IteratorAndIterable<String> Lst =  new IteratorAndIterable<>();
//Valuse
	Lst.add("EAST");
	Lst.add("WEST");
	Lst.add("NORTH");
	Lst.add("SOUTH");
//For each loop to extract values from the iterator
	for (String indx : Lst) {
//Print
	System.out.println(indx);
		}
	}
}

EAST
WEST
NORTH
SOUTH