Three kinds of iteration, enhanced for loop

Ordinary for loop can be deleted, but the index for -
iterator can be deleted, but you must use the iterator's own remove method, otherwise there will be concurrent modification abnormal
enhanced for loop can not be deleted

Import of java.util.ArrayList;
 Import the java.util.Iterator;
 Import com.heima.bean.Person; 

public  class demon_bigFor {
     / * 
     * Enhanced for loop 
     * implemented with underlying iterator 
     * 
     * Format: 
     * for (element data type variable : set array or collection) { 
     * can use variable, the variable element is 
     *} 
     * / 
    public  static  void main (String [] args) {
         // the demo1 ();
         // demo2 (); 
        the ArrayList <String> L3 = new new the ArrayList <> (); 
        l3.add ( "A"  );
        l3.add ("b");
        l3.add("c");
        l3.add("d");
        //  1，普通for循环
        /*for (int i = 0; i < l3.size(); i++) {
            if ("b".equals(l3.get(i))) {
                l3.remove(i);
            }
        }
        System.out.println(l3);*/
        
        // 2，迭代循环
        Iterator<String> iterator = l3.iterator();
        while (iterator.hasNext()) {
            String string = iterator.next();
            if ("b".equals(string)) {
                iterator.remove();
            }
            
        }
    }

    public static void demo2() {
        ArrayList<Person> l2 = new ArrayList<>();
        l2.add(new Person("张三",23));
        l2.add(new Person("李四",24));
        l2.add(new Person("王五",25));
        l2.add(new Person("赵柳",26));
        l2.add(new Person("周七",27));
        for (Person person : l2) {
            System.out.println(person);
        }
    }

    public static void demo1() {
        int[] arr = {11,22,33,44,55};
        /*for (int i : arr) {
            System.out.println(i);
        }*/
        ArrayList<String> l1 = new ArrayList<>();
        l1.add("a");
        l1.add("b");
        l1.add("c");
        l1.add("d");
        for (String string : l1) {
            System.out.println(string);
        }
    }

}