Iterator<Integer> it=panel1(1,5);
    for(;it.hasNext();)
    System.out.println(it.next()); // mostra 1 2 3 4 5

import java.util.List;
import java.util.AbstractList;
import java.util.Iterator;

public class Panel{

    public Iterator<Integer> panel1(int begin, int end){
        it = new IntRangeIterator(begin, end);
        return it;
    }

    public static void main(String[] args) {

        Iterator<Integer> it=panel1(1,5);
        for(;it.hasNext();)
        System.out.println(it.next()); // affiche 1 2 3 4 5
    }
}

class IntRangeIterator implements Iterator<Integer> {
    private int nextValue;
    private final int max;
    public IntRangeIterator(int min, int max) {

    if (min > max) {
          throw new IllegalArgumentException("min must be <= max");
        }
        this.nextValue = min;
        this.max = max;
    }

    public boolean hasNext() {
        return nextValue <= max;
    }

    public Integer next() {
        if (!hasNext()) {
            throw new NoSuchElementException();
        }
        return Integer.valueOf(nextValue++);
    }

    public void remove() {
        throw new UnsupportedOperationException();
    }
}

Panel.java:9: error: cannot find symbol
                it = new IntRangeIterator(begin, end);
                ^
  symbol:   variable it
  location: class Panel
Panel.java:10: error: cannot find symbol
                return it;
                       ^
  symbol:   variable it
  location: class Panel
Panel.java:15: error: non-static method panel1(int,int) cannot be referenced from a static context
                Iterator<Integer> it=panel1(1,5);