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C# -- > java 过程中遇到的问题记录及解决
author:lijun
date:2006-01-02

0. 预备知识
 C# namespace -- java package
 object x --- Object x
 enum -- jdk 1.5 support , --> static final int
 java 的一个class 文件存在多个class时，只能有一个是public类型的。
 lock -- synchrionized
 ref -- 地址引用。
  void func(ref xx) --- xxtype func(xx)
     使用时 xx = func(xx);
  当多个ref时，只好用全局变量来实现此效果。

 as xx -- (xx) 强制类型转换。
 string -- String 改变大小写. suggest match case,match whole word then replaceAll.
 ToString() -- toString()
 bool --- boolean
 object --- Object
 Console.WriteLine(str); --- System.out.println(str);
 wait,pulse,pulseall -- wait, notify,notifyall
 strFromList.Trim();  --- strFromList.trim();
 strFragAttr.ToLower().Equals(strSelect.ToLower())
 --- strFragAttr.toLowerCase().equals(strSelect.toLowerCase()
 strSql.Substring(nFromIndex,nWhereIndex-nFromIndex) --- strSql.substring(nFromIndex,nWhereIndex)
 // 分割字符
        String[] s=strTableField.Split(new char[]{'.'}); --- String[] s=strTableField.split("\\.");
 // 判断字符串相等 , 如果在java中 用 ==有时会出现问题。
  str1 == str2  --- str1.equals(str2)

 // 有关foreach转换成 for 循环要这样来转换:
 foreach(ArrayList arr in arrConjunctiveNF) --->
                        for(int j=0;j<=arrConjunctiveNF.size()-1;j++)
                        {
                                ArrayList arr =(ArrayList)(arrConjunctiveNF.get(j));

 array[j]; --- arraylist.get(j);
 array.Count --- array.size();

 Hashtable tableJoinAttributes=Hashtable.Synchronized(new Hashtable());
  --- =new Hashtable(); //Hashtable is synchronized.
  or --- Map m = Collections.synchronizedMap(new HashMap(...));

 PredicateElem e=arr[0] as PredicateElem;  --- PredicateElem e = (PredicateElem)arr[0];

 DictionaryEntry --- Map.Entry
 arr.RemoveAt(i); --- arr.remove(i);
 arr.sort() ---- Collections.sort(arr);

  arrAttr.Add(e.leftOpValue); --- arrAttr.add(e.leftOpValue)

  tableJoinAttributes[leftTable] --- get(leftTable);

 tableJoinAttributes[leftTable]=newArr; ---  this.tableJoinAttributes.put(leftTable,newArr);

 tableJoinAttributes.Contains(leftTable)
 -- tableJoinAttributes.containsKey(leftTable)

 stack.Push() Pop() --- stack.push() pop()

                  foreach(DictionaryEntry entry in this.tableJoinAttributes)
                  {
                          ArrayList arr=entry.Value as ArrayList;
                          this.TrimEqual(arr);
                  }
    ------>
                    Set entrys = tableJoinAttributes.entrySet();
                    Iterator it = entrys.iterator();
                    while(it.hasNext()){
                      ArrayList arr = (ArrayList)((Map.Entry)it.next()).getValue();
                      TrimEqual(arr);
                    }

   又一个例子
                        tableIndexCounts=new Hashtable();
   Foreach(Dictionaryentry Entry In Item.Tableindexs)
   {
    Tableindexcounts[Entry.Key]=(Entry.Value As Hashtable).Count;
   }
   ---->
                            tableIndexCounts=new Hashtable();                           
                            Set entrys =  item.tableIndexs.entrySet();
                            Iterator it = entrys.iterator();
                            while(it.hasNext())
                            {
                              Map.Entry entry = (Map.Entry)it.next();
                              tableIndexCounts.put(entry.getKey(),((Hashtable)entry.getValue()).size());
                            }

   对于HashMap 之类的也可以用2个Iterator 同步访问Key & value.

Class的访问权限：
每个编译单元（文件）仅能有一个public class。即：只能拥有一个由public class所表现的单一public接口。可以拥有许多个支持用的friendly classes（默认的访问权限，不需要任何关键字）。如果生命不止一个public class，编译器会给出错误。
public class的名称必须跟编译单元（文件）名称相同。
编译单元内可以不含任何public class，所以可以任意给定文件名（这个以前不知道）。 

 // 有关实现接口interface的转换
 public class RangeEndPoint:IComparable  --- public class RangeEndPoint implements Comparable
 CompareTo() --- compareTo()

 public class myexample:IComparer
 {  
  public int Compare(object x, object y){}
 }
 --->
 public class myexample implements Comparator{
   public int compare(Object o1, Object o2) {
   //Returns:a negative integer, zero, or a positive integer as the first argument is less than, equal to, or greater than the second.
     return 0;
   }
   // optional
   public boolean equals(Object obj) {
     return false;
   }
 }

 candidate.Sort(new CompareOfTableHorFrag());
 --->   Collections.sort(candidate,new CompareOfTableHorFrag()); 
 or --->
        TableNameAndJoinInfo[] candidate_convert=(TableNameAndJoinInfo[])candidate.toArray();
        Arrays.sort(candidate_convert,new CompareOfTableHorFrag());

 [Serializable]
 ---> implements Serializable

 // c# 的thread 方法名无所谓
 ThreadClassExec exec=new ThreadClassExec();
 Thread threadListen=new Thread(new ThreadStart(exec.ListenThreadMethod));
 threadListen.Start();
 ---> Thread threadListen=new Thread(new implemtsRunableClass())
 class implemtsRunableClass implements Runable{
 public void run(){
 }}
 threadListen.start();

 int nParentIndex; arrBegin.add(nParentIndex)
 --->
        arrBegin.add(new Integer(nParentIndex));

 dataTable,dataTable.Rows ---> CachedRowSet
 dataTable.Rows.Count ---> dataTable.size()

 DataRow row=this.dataTable.Rows[i];
 ---> java 的5.0 版本的 rowset 不提供row , 只能通过metadata得到列数，再遍历
 ResultSetMetaData rsm= dataTable.getMetaData();
        while(crs_down.next()) {
          System.out.print(" "+crs_down.getObject(1));

  key.GetType()==typeof(string)
  ---> if(key.getClass()==String.class)  
  or --> if(key instanceof String)  但是这个好像有是父类时仍相等的问题。不是完全相等.

 System.Data.DataTable.Clone() ,
 ---->
 CachedRowSet.createCopySchema() ,

 Deep Copy:
 System.Data.DataTable.Copy()
 ----> CachedRowSet.createCopy();

 Thread.CurrentThread.Name
 ---> Thread.currentThread.getName();