简单动态数组的实现代码

以下是本人动态数组实现的源代码，仅供参考，不足之处请指正：

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import java.util.*; public class My_List implements Collection{ /***************************************************************/     //测试模块     //主方法,测试用     public static void main(String [] args){         /*         My_List ma = new My_List();         //测试add方法         ma.add("abc");         ma.add("asdfj");         System.out.println(ma.size());         //测试get方法         System.out.println(ma.get(0));         System.out.println(ma.get(1));         //测试add方法二         ma.add(1,"改变后的值");         System.out.println(ma.get(1));         //测试addAll方法         List lis = new ArrayList();         lis.add("1");         lis.add("2");         lis.add("3");         ma.addAll(1,lis);         System.out.println("执行addAll之后的长度" + ma.size());         System.out.println("执行addAll之后的第四个元素是 " + ma.get(3));         //测试clear函数         //ma.clear();         //System.out.println("clear函数执行之后的元素个数 " + ma.size());         //测试contains方法         System.out.println("是否包含1字符串？ " + ma.contains("1"));         System.out.println("是否包含23字符串？ " + ma.contains("23"));                   //lis.add("asddfj");         //测试containsAll方法         System.out.println("ma是否包含lis的所有元素？ " + ma.containsAll(lis));         //测试equals方法         My_List lis2 = new My_List();         lis2.add("abc");         lis2.add("123");         lis2.add("我和你");                   My_List lis3 = new My_List();         lis3.add("abc");         lis3.add("123");         lis3.add("我he");         boolean b3 = lis2.equals(lis3);         System.out.println(b3);         //测试indexOf方法         //lis.add(null);         //int index_FirstNull = lis.indexOf(null);         lis.add("asdjsdfaasdaa");         lis.add(null);         System.out.println("3第一次出现的索引为  " + lis.indexOf("3"));                   //测试lastIndexOf         lis.add(null);         lis.add("我和你");         lis.add(null);         lis.add("3");         System.out.println("最后一次出现我和你的地方  " + lis.lastIndexOf("我和你"));         //测试isEmpty         System.out.println("lis.isEmpty ?  " + lis.isEmpty());         My_List lis_isEmpty = new My_List();         System.out.println("lis_isEmpty.isEmpty ?  " + lis_isEmpty.isEmpty());                   //测试remove                   System.out.println("remove之前lis的长度为 " + lis.size());         System.out.println("remove之前，index = 2的值为  " + lis.get(2));         System.out.println("remove之前，index = 6的值为  " + lis.get(6));         //lis.remove(null);         //lis.remove(10);         lis.remove(1);         System.out.println("remove之后lis的长度为 " + lis.size());         System.out.println("remove之后，index = 1的值为  " + lis.get(1));         System.out.println("remove之后，index = 4的值为  " + lis.get(4));         */         //removeAll测试         My_List lis = new My_List();         lis.add("1");         lis.add("2");         lis.add("3");         lis.add("我和你");         lis.add(null);         lis.add("4");         lis.add("5");         lis.add("6");         /*         System.out.println("removeAll之前lis的长度为 " + lis.size());         System.out.println("removeAll之前，index = 1的值为  " + lis.get(1));         List lis_removeAll = new ArrayList();         lis_removeAll.add("我和你");         lis_removeAll.add("3");         lis_removeAll.add(null);         lis.removeAll(lis_removeAll);                   //System.out.println("removeAll之前，index = 6的值为  " + lis.get(6));;         System.out.println("removeAll之后lis的长度为 " + lis.size());         System.out.println("removeAll之后，index = 3的值为  " + lis.get(3));         System.out.println("removeAll之后，index = 4的值为  " + lis.get(4));         */                   //方法retainAll测试         /*         List lis_retainAll = new ArrayList();         lis_retainAll.add("1");         lis_retainAll.add("2");         lis_retainAll.add("我和你");         lis_retainAll.add("null");         //lis_retainAll.add();         System.out.println("执行retainAll方法之前的lis的size =  " + lis.size());         lis.retainAll(lis_retainAll);         System.out.println("执行retainAll方法之后的lis的size =  " + lis.size());         System.out.println("执行完retainAll方法之后lis的值输出 = ");         System.out.println(lis.get(2));         */                   //set方法的测试         /*         lis.set(2,"soga");         System.out.println("索引2值替换之后变为" + lis.get(2));         //subList方法的测试         My_List ml = new My_List();         ml = lis.subList(2,4);         System.out.println("subList返回的对象长度为 = " + ml.size());         System.out.println("其中索引1的值为 = " + ml.get(1));         */         /*         //测试toArray         Object [] ob_test1 = new Object[]{"2","4","akjsdf","我和你",null};         Object [] ob = lis.toArray(ob_test1);         System.out.println("toArray的长度为  " + ob.length);         System.out.println("返回数组的第一个值为 " + ob[0]);         */                   //迭代方法测试         /*         Iterator it = lis.iterator();         while(it.hasNext()){             System.out.println(it.next());             it.remove();             //it.remove();         }         System.out.println("迭代之后的size = " + lis.size());         */         //返回哈希值方法测试         int has = lis.hashCode();         System.out.println("列表哈希值为  " + has);     } /********************************************************************/     //My_List代码     /*     *成员变量     */     Object [] object = null;     //初始的数组长度     int len = 10;     //定义每次增加的长度     int addLen = 10;     //动态数组当前的元素个数     private int size;     //构造方法     public My_List(){         object = new Object[len];         size = 0;     }           /*     *以下是实现Collection的方法     */     //add方法一     public boolean add(Object ob){         boolean rtn = false;         //判断当前动态数组对象的数目         if(size == object.length){             //相应地总长度增长             len = len + 10;             //如果当前的数组已满，则将之重新放进另一个数组中             //先定义一个数组存储当前的数组值             Object [] object_before = object;             object = new Object[len];             for(int i = 0;i<size;i++){                 object[i] = object_before[i];             }             //执行添加操作             object[size] = ob;             size++;         }else{             object[size] = ob;             size++;         }         rtn = true;         return rtn;     }     //add方法二,index超出范围则抛出异常     public void add (int index,Object ob){         if(index<0||index>size-1){             new RuntimeException("IndexOutOfBoundsException");         }else{             object[index] = ob;         }     }     //addAll方法     public boolean addAll(int index,Collection c){         boolean rtn = false;         if(index<0||index>size-1){             throw new RuntimeException("IndexOutOfBoundsException");         }else if(c==null){             throw new RuntimeException("NullPointerException");         }else{             for(int i = 0;i<c.size();i++){                 add(c.toArray()[i]);             }             rtn = true;         }         return rtn;     }     public boolean addAll(Collection c){         boolean rtn = false;         int size_before = size;         for(int i = 0;i<c.toArray().length;i++){             add(c.toArray()[i]);         }         if(size_before != size){             rtn = true;         }         return rtn;     }     //移除所有元素     public void clear(){         for(int i = 0;i<size;i++){             object[i] = 0;         }         size = 0;     }     //判断是否包含指定元素     public boolean contains(Object ob){         boolean rtn = false;         for(int i = 0;i<size;i++){             if(ob == null){                 if(object[i] == null){                     rtn = true;                     break;                 }             }else{                 if(ob.equals(object[i])){                     rtn = true;                     break;                 }             }         }         return rtn;     }     //判断是否包含Collection的所有元素     public boolean containsAll(Collection c){         for(int i = 0;i<c.size();i++){             if(!contains(c.toArray()[i])){                 return false;             }         }         return true;     }     //equals方法     public boolean equals(Object ob){         boolean rtn = true;         //先判断对象是否是个列表         if(ob.getClass().getName().equals("My_List")){             //判断两者的长度是否一致             if(((My_List)ob).size()==size){                 //判断对应位置对应元素是否相等                 for(int i = 0;i<size;i++){                     if(!(((My_List)ob).get(i).equals(object[i]))){                         return false;                     }                 }             }else{                 rtn = false;             }                       }else{             rtn = false;         }         return rtn;     }     //get方法,超出范围抛出异常     public Object get(int index){         Object rtn = null;         if(index<0||index>size-1){             throw new ArrayIndexOutOfBoundsException("IndexOutOfBoundsException");         }else{             rtn = object[index];         }         return rtn;     }           //返回表的哈希码值(未实现)           public int hashCode(){         int rtn = 0;         int hashCode = 1;         Iterator i = iterator();         while (i.hasNext()) {             Object obj = i.next();             hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());         }         rtn = hashCode;         return rtn;     }           //返回第一次出现该元素的索引，不存在，返回-1     public int indexOf(Object ob){         int rtn = -1;         //判断Object和列表中的元素是否兼容         for(int i = 0;i<size;i++){             if(object[i] == null){                 if(ob == null){                     return i;                 }             }else{                 if(object[i].equals(ob)){                     return i;                 }             }         }         return rtn;     }     //返回此元素最后出现的位置     public int lastIndexOf(Object ob){         int rtn = -1;         for(int i = size-1;i>=0;i--){             if(object[i] == null){                 if(ob == null){                     return i;                 }             }else{                 if(object[i].equals(ob)){                     return i;                 }             }         }         return rtn;     }     //判断列表是否包含元素     public boolean isEmpty(){         boolean rtn = true;         if(size != 0){             rtn = false;         }         return rtn;     }     //返回按照适当顺序上进行迭代的迭代器     public Iterator iterator (){         Iterator rtn = null;         rtn = new My_Iterator(this);         return rtn;     }     //移除元素,返回被移除的元素，如果传入的索引值超出范围抛出异常     public Object remove(int index){         Object rtn = null;         if(index<0||index>=size){             throw new RuntimeException("IndexOutOfBoundsException");         }else{             rtn = object[index];             for(int i = index;i<size - 1;i++){                 object[i] = object[i+1];             }             size--;         }         return rtn;     }     public boolean remove(Object ob){         boolean rtn = false;         int index = indexOf(ob);         if(index!=-1){             remove(index);             rtn = true;         }         return rtn;     }     //移除所有元素(问题起点)     public boolean removeAll(Collection c){         boolean rtn = false;         //存储当前的size值，用于之后判断列表是否有元素发生了变动         int size_before = size;         Object [] ob_toArray = c.toArray();         for(int i = 0;i<c.size();i++){             remove(ob_toArray[i]);         }         //由于当c是对象本身时，其处于变化中，所以另外处理         if((this == null && c == null)||this.equals(c)){             clear();         }         //判断表中的元素是否发生了变化         if(size_before == size){             rtn = true;         }         return rtn;     }     //保留列表中的元素(代码质量的问题)(question)     public boolean retainAll(Collection c){         boolean rtn = false;         //定义一个整形变量存储当前siez以便用于判断列表的值是否发生改变         int size_before = size;         Object [] ob_toArray  = c.toArray();         for(int i = 0;i<size;i++){             for(int j = 0;j<ob_toArray.length;j++){                 if(object[i]==null){                     if(ob_toArray[j]==null){                         break;                     }                 }else{                     if(object[i].equals(ob_toArray[j])){                         break;                     }                 }                 if(j==ob_toArray.length-1){                     //遍历完没有发现相应的元素，执行remove                     remove(i);                     //由于执行remove之后原来动态数组中的元素分布发生前移，所以i--                     i--;                 }             }         }         if(size_before!=size){             rtn = true;         }         return rtn;     }     //替换元素,返回以前元素     public Object set(int index,Object ob){         Object rtn = null;         rtn = object[index];         object[index] = ob;         return rtn;     }     //size()返回列表中的元素数目     public int size(){         return size;     }     //返回从fromIndex到toIndex的元素，前包括后不包括     public My_List subList(int fromIndex,int toIndex){         My_List rtn = null;         if((fromIndex>toIndex)||(fromIndex<0)||(toIndex>size-1)){             throw new RuntimeException("IndexOutOfBoundsException");         }else{             rtn = new My_List();             for(int i = fromIndex;i<toIndex;i++){                 rtn.add(get(i));             }         }         return rtn;     }     //返回所有元素     public Object[] toArray(){         Object [] rtn = null;         rtn = object;         return rtn;     }     //返回列表中的元素     public Object[] toArray(Object [] ob){         Object [] rtn = null;         My_List ml = new My_List();         for(int i = 0;i<ob.length;i++){             if(contains(ob[i])){                 ml.add(ob[i]);             }         }         rtn = ml.toArray();         return rtn;     }       }     /*************************************************************************/   //迭代器的实现类 class My_Iterator implements Iterator{     My_List ml = null;     Object [] object = null;     //定义构造函数     public My_Iterator(My_List ml){         this.ml = ml;         object = ml.toArray();     }     /*     *以下是实现Iterator接口的方法     */     public boolean hasNext(){         boolean rtn = true;         if(point>(ml.size()-1)){             rtn = false;         }         return rtn;     }     //定义一个指针变量，用于存储next时的当前游标     private int point = 0;     public Object next(){                   //每次调用next方法前，先将指针变量指向初始位置         Object rtn = null;         if(point>(ml.size()-1)){             throw new RuntimeException("NoSuchElementException");         }else{             rtn = object[point];             point++;             remove_CanUsed = true;         }         return rtn;     }     //定义一个布尔变量用以标记remove已经是否被调用，同时，该变量在next方法调用后初始化为true,在remove被调用后被初始化为fals     private boolean remove_CanUsed = false;     public void remove(){         //判断是否和当前的point一致         if(remove_CanUsed){             ml.remove(point-1);//这里减一是因为上面的next操作完后指针变量自增了             //由于remove后操作的列表对应的排列顺序也改变了，所以指针相应地跟着减1             point--;         }else{             throw new RuntimeException("IllegalStateException");         }         remove_CanUsed = false;     } }

　　代码有点长，各位需要就参考下，不足之处请指正！