Study《JavaScript实现ArrayList》

最新推荐文章于 2025-05-27 10:26:35 发布

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本文介绍了一种使用JavaScript实现的ArrayList，包括初始化容量、元素获取、添加、删除等基本操作。

仿照java用数组实现ArrayList

/*******************************************************************************
* JavaScript实现的ArrayList.
*
* @author Naga{jiangdragon@126.com}
* @version 2012/06/06
*
******************************************************************************/
function ArrayList() {
var args = ArrayList.arguments;
var initCapacity = 10;
if (args != null && args.length > 0)
initCapacity = args[0];
var elementData = new Array(initCapacity);
var size = 0;

this.size = function() {
  return size;
};
this.isEmpty = function() {
  return size == 0;
};
this.contians = function() {
  return this.indexOf(obj) >= 0;
};
this.indexOf = function(obj) {
  if (obj == null) {
   for ( var i = 0; i < size; i++)
    if (elementData[i] == null)
     return i;
  } else {
   for ( var i = 0; i < size; i++)
    if (elementData[i] == obj)
     return i;
  }
  return -1;
};
this.lastIndexOf = function(obj) {
  if (obj == null) {
   for ( var i = size - 1; i >= 0; i--)
    if (elementData[i] == null)
     return i;
  } else {
   for ( var i = size - 1; i >= 0; i--)
    if (elementData[i] == obj)
     return i;
  }
  return -1;
};
this.get = function(index) {
  rangeCheck(index);
  return this.elementData[index];
};
this.setElementAt = function(index, obj) {
  rangeCheck(index);
  var oldValue = elementData[index];
  this.elementData[index] = obj;
  return oldValue;
};
this.add = function(obj) {
  ensureCapacity(size + 1);
  elementData[size++] = obj;
  return true;
};

this.addElementAt = function(index, obj) {
  if (index > size || index < 0) {
   alert("ArrayIndexOutOfBoundsException," + index + ">=" + size);
   return;
  }
  ensureCapacity(size + 1);
  elementData[index] = element;
  size++;
};
this.remove = function(index) {
  rangeCheck(index);
  var oldValue = elementData[index];
  for ( var i = index; i < size - 1; i++) {
   elementData[i] = elementData[i + 1];
  }
  elementData[--size] = null;
  return oldValue;
};
this.clear = function() {
  for ( var i = 0; i < size; i++)
   elementData[i] = null;
  size = 0;
};
this.toString = function() {
  if (size == 0)
   return "{}";
  var str = "{";
  for ( var i = 0; i < size; i++) {
   str += elementData[i];
   if (i == size - 1)
    return str + "}";
   str += ",";
  }
};
function ensureCapacity(minCapacity) {
  var oldCapacity = elementData.length;
  if (minCapacity > oldCapacity) {
   var oldData = elementData;
   var newCapacity = parseInt((oldCapacity * 3) / 2 + 1);
   if (newCapacity < minCapacity)
    newCapacity = minCapacity;
   elementData = new Array(newCapacity);
   for ( var i = 0; i < oldCapacity; i++) {
    elementData[i] = oldData[i];
   }
  }
};