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通过下面表格进行对比：
异同点 | 普通集合 ArrayList和Hashtable | 泛型集合List<T>与Dictionary<K,V> |
不同点
| ArrayList的添加元素的Add方法返回int类型，代表添加成功后该元素在集合中的索引位置； | 泛型集合List<T>的添加元素的Add方法返回类型为void |
Hashtable集合遍历可以使用 foreach (DictionaryEntry de in employees) { MessageBox.Show("元素的key为为："+de.Key.ToString()+"，元素的信息为："+((SE)de.Value).Show()); }
| Dictionary<K,V>的遍历只有下面二种： MessageBox.Show("--Foreach的keys 遍历信息--"); foreach (string o in employees.Keys) { SE s = employees[o.ToString()]; MessageBox.Show(s.Show()); }
MessageBox.Show("--Foreach的values 遍历信息--"); foreach (SE s in employees.Values) { MessageBox.Show(s.Show()); } | |
可以增加任何类型，属于弱类型操作 | 增加元素时类型严格检查，属于强类型操作 | |
添加和读取元素时，需要做装箱和拆箱操作 | 添加和读取元素时，无需做装箱和拆箱操作 | |
相同点 | 除了上面的区别外，ArrayList与List<T>、Hashtable与Dictionary<K,V>的操作基本相同 | |
之所以泛型集合在编程被频繁使用（基本上替代了数组和普通集合），主要是其有以下优点：
1、实现了代码重用，未来的主流技术；
2、性能高，避免了繁琐的装箱和拆箱操作；
3、提供了更好的类型安全性（添加元素时做类型检查）。
4、CLR(公共语言运行时)支持泛型。
泛型集合List<T>的操作相关代码如下：
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication4
{
public partial class FormList : Form
{
List<SE> employees;
SE s;
public FormList()
{
InitializeComponent();
}
private void btnAdd_Click(object sender, EventArgs e)
{
SE se = new SE();
se.No = txtNo.Text;
se.Name = txtName.Text;
se.Age = Convert.ToInt32(txtAge.Text);
employees.Add(se);
s = se;
MessageBox.Show("添加成功");
}
private void Form1_Load(object sender, EventArgs e)
{
employees = new List<SE> { new SE { No = "s1000", Name = "张三", Age = 20 }, new SE { No = "s1001", Name = "李四", Age = 21 }, new SE{No="s1002",Name="王五",Age=22}};
}
private void btnCount_Click(object sender, EventArgs e)
{
MessageBox.Show("List集合中元素的个数为："+employees.Count);
}
private void btnShow_Click(object sender, EventArgs e)
{
int index = -1;
bool bSuccess = int.TryParse(txtIndex.Text.Trim(), out index);
if (bSuccess)
{
if (index > employees.Count -1)
{
MessageBox.Show("输入的索引下标超出范围");
}
else
{
SE s = employees[index];
MessageBox.Show(s.Show());
}
}
else
{
MessageBox.Show("请输入整数类型！");
}
}
private void btnForeach_Click(object sender, EventArgs e)
{
for (int i = 0; i < employees.Count; i++)
{
MessageBox.Show(employees[i].Show());
}
MessageBox.Show("------Foreach的遍历信息-----------");
foreach (SE s in employees)
{
MessageBox.Show(s.Show());
}
}
private void btnDelete_Click(object sender, EventArgs e)
{
MessageBox.Show("删除前的集合中的所有素为：");
for (int i = 0; i < employees.Count; i++)
{
MessageBox.Show(employees[i].Show());
}
employees.RemoveAt(1);
MessageBox.Show("删除索引下标为1的元素后的集合中的元素为：");
for (int i = 0; i < employees.Count; i++)
{
MessageBox.Show(employees[i].Show());
}
employees.Remove(s);
MessageBox.Show("删除最后添加的元素后的集合中的元素为：");
for (int i = 0; i < employees.Count; i++)
{
MessageBox.Show(employees[i].Show());
}
employees.Clear();
MessageBox.Show("清空集合后的集合中的元素为：");
for (int i = 0; i < employees.Count; i++)
{
MessageBox.Show(employees[i].Show());
}
}
private void btnAddPM_Click(object sender, EventArgs e)
{
PM pm = new PM();
pm.No = 1001;
pm.Name = "张三";
pm.YearOfWork = 5;
//employees.Add(pm);
MessageBox.Show("项目经理信息添加失败！");
}
}
}泛型集合Dictionary<K,V>的操作相关代码如下：
using System;
using System.Collections;
using System.Collections.Generic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
nam using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
nam using System;
using System.Collections;
using System.Collections.Generic;
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
nam using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace WindowsFormsApplication4
{
public partial class FormDictionary : Form
{
Dictionary<string,SE> employees;
public FormDictionary()
{
InitializeComponent();
}
private void btnAdd_Click(object sender, EventArgs e)
{
SE se = new SE();
se.No = txtNo.Text;
se.Name = txtName.Text;
se.Age = Convert.ToInt32(txtAge.Text);
employees.Add(se.No, se);
MessageBox.Show("添加成功！");
}
private void Form1_Load(object sender, EventArgs e)
{
employees = new Dictionary<string, SE>();
SE s1 = new SE();
s1.No = "s0001";
s1.Name = "张三";
s1.Age = 19;
SE s2 = new SE();
s2.No = "s0002";
s2.Name = "李四";
s2.Age = 22;
SE s3 = new SE();
s3.No = "s0003";
s3.Name = "王五";
s3.Age = 20;
employees.Add(s1.No, s1);
employees.Add(s2.No, s2);
employees.Add(s3.No, s3);
}
private void btnCount_Click(object sender, EventArgs e)
{
MessageBox.Show("Dictionary集合中元素的个数为："+employees.Count);
}
private void btnShow_Click(object sender, EventArgs e)
{
string key = txtSeNo.Text.Trim();
if (employees.ContainsKey(key))
{
SE se = employees[key];
MessageBox.Show(se.Show());
}
else
{
MessageBox.Show(key+"不在字典中！");
}
}
private void btnForeach_Click(object sender, EventArgs e)
{
MessageBox.Show("------Foreach的keys 遍历信息-----------");
foreach (string o in employees.Keys)
{
SE s = employees[o.ToString()];
MessageBox.Show(s.Show());
}
MessageBox.Show("------Foreach的values 遍历信息-----------");
foreach (SE s in employees.Values)
{
MessageBox.Show(s.Show());
}
}
private void btnDelete_Click(object sender, EventArgs e)
{
employees.Remove("s0002");
MessageBox.Show("删除员工的编号为's0002'后的集合中的元素为：");
foreach (SE s in employees.Values)
{
MessageBox.Show(s.Show());
}
employees.Clear();
MessageBox.Show("清空集合后的集合中的元素为：");
foreach (SE s in employees.Values)
{
MessageBox.Show(s.Show());
}
}
}
}