Iterator

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这里写图片描述
public interface Collection {    void add(Object o);    int size();}----------public class ArrayList implements Collection {    private int size=0;    Object[] os = new Object[10];    @Override    public void add(Object o) {        if(size == os.length){            Object[] newOs = new Object[os.length*2];            System.arraycopy(os, 0, newOs, 0, os.length);            os = newOs;        }        os[size] = o;        size++;    }    @Override    public int size() {        return size;    }    Iterator iterator(){        ArrayListIterator it = new ArrayListIterator();        return it;    }    class ArrayListIterator implements Iterator{        int current = 0;        @Override        public boolean hasNext() {            if(current==size)                return false;            else {                 current++;///                return true;            }        }        @Override        public Object next() {            return os[current-1];        }    }}----------import static org.junit.Assert.*;import org.junit.Assert;import org.junit.Test;/** * @author Thinkpad * */public class ArrayListTest {    /**     * Test method for {@link ArrayList#add(java.lang.Object)}.     */    @Test    public void testAdd() {        String str="test---";        ArrayList al = new ArrayList();        for(int i=0;i<3;i++){            al.add(str+i);        }        Iterator it = al.iterator();        while(it.hasNext()){            System.out.println(it.next());        }    } }----------public interface Iterator {    boolean hasNext();    Object next();}----------public class LinkedList implements Collection {    private int size = 0;    Node head = new Node();    Node tail = head;    @Override    public void add(Object o) {        Node n = new Node();        tail.setData(o);        tail.setNode(n);        tail = n;        size++;    }    @Override    public int size() {        return size;    }    Iterator iterator() {        return new LinkedListIterator();    }    private class Node {        Object data;        Node node;        public Object getData() {            return data;        }        public void setData(Object data) {            this.data = data;        }        public Node getNode() {            return node;        }        public void setNode(Node node) {            this.node = node;        }    }    class LinkedListIterator implements Iterator {        Node temp = head;        Node data = temp;        @Override        public boolean hasNext() {            if (temp.node == null)                return false;            else {                data = temp;                temp = temp.node;                return true;            }        }        @Override        public Object next() {            return data.data;        }    }}----------import static org.junit.Assert.*;import org.junit.Assert;import org.junit.Test;/** * @author Thinkpad * */public class LinkedListTest {    /**     * Test method for {@link LinkedList#add(java.lang.Object)}.     */    @Test    public void testAdd() {        LinkedList ll = new LinkedList();        ll.add(new String("ni hao a!"));        ll.add(new String("wo ye hao a!"));        Iterator it = ll.iterator();        while(it.hasNext()){            System.out.println(it.next());        }    }}
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